Contact Dermatitis

Contact allergy to cobalt, chromium, and especially nickel, may be higher in European metalworkers than in all European male patients with allergic contact dermatitis, a systematic review and meta-analysis reports.

“Metal allergy to all three metals was significantly more common in European metalworkers with dermatitis attending patch test clinics as compared to ESSCA [European Surveillance System on Contact Allergies] data, indicating a relationship to occupational exposures,” senior study author Jeanne D. Johansen, MD, professor, department of dermatology and allergy, Copenhagen University Hospital, Hellerup, Denmark, and colleagues at the University of Copenhagen wrote in Contact Dermatitis. “However, confounders could not be accounted for.”

How common is metal allergy in metalworkers?

Occupational hand eczema is known to be common in metalworkers. Touching oils, greases, metals, leather gloves, rubber materials, and metalworking fluids as they repeatedly cut, shape, and process raw metals and minerals derived from ore mining exposes metalworkers to allergens and skin irritants, the authors wrote. But the prevalence of allergy to certain metals has not been well characterized.

So they searched PubMed for full-text studies in English that reported metal allergy prevalence in metalworkers, from the database’s inception through April 2022.

They included studies with absolute numbers or proportions of metal allergy to cobalt, chromium, or nickel, in all metalworkers with suspected allergic contact dermatitis who attended outpatient clinics or who worked at metalworking plants participating in workplace studies.

The researchers performed a random-effects meta-analysis to calculate the pooled prevalence of metal allergy. Because 85%-90% of metalworkers in Denmark are male, they compared the estimates they found with ESSCA data on 13,382 consecutively patch-tested males with dermatitis between 2015 and 2018.

Of the 1,667 records they screened, they analyzed data from 29 that met their inclusion criteria: 22 patient studies and 7 workplace studies involving 5,691 patients overall from 22 studies from Europe, 5 studies from Asia, and 1 from Africa. Regarding European metalworkers, the authors found:

• Pooled proportions of allergy in European metalworkers with dermatitis referred to patch test clinics were 8.2% to cobalt (95% confidence interval, 5.3%-11.7%), 8.0% to chromium (95% CI, 5.1%-11.4%), and 11.0% to nickel (95% CI, 7.3%-15.4%).
• In workplace studies, the pooled proportions of allergy in unselected European metalworkers were 4.9% to cobalt, (95% CI, 2.4%-8.1%), 5.2% to chromium (95% CI, 1.0% - 12.6%), and 7.6% to nickel (95% CI, 3.8%-12.6%).
• By comparison, ESSCA data on metal allergy prevalence showed 3.9% allergic to cobalt (95% CI, 3.6%-4.2%), 4.4% allergic to chromium (95% CI, 4.1%-4.8%), and 6.7% allergic to nickel (95% CI, 6.3%-7.0%).
• Data on sex, age, body piercings, and atopic dermatitis were scant.

Thorough histories, protective regulations and equipment

Providers need to ask their dermatitis patients about current and past occupations and hobbies, and employers need to provide employees with equipment that protects them from exposure, Kelly Tyler, MD, associate professor of dermatology, Ohio State University Wexner Medical Center, Columbus, said in an interview.

“Repeated exposure to an allergen is required for sensitization to develop,” said Dr. Tyler, who was not involved in the study. “Metalworkers, who are continually exposed to metals and metalworking fluids, have a higher risk of allergic contact dermatitis to cobalt, chromium, and nickel.”

“The primary treatment for allergic contact dermatitis is preventing continued exposure to the allergen,” she added. “This study highlights the importance of asking about metal or metalworking fluid in the workplace and of elucidating whether the employer is providing appropriate protective gear.”

To prevent occupational dermatitis, workplaces need to apply regulatory measures and provide their employees with protective equipment, Dr. Tyler advised.

“Body piercings are a common sensitizer in patients with metal allergy, and the prevalence of body piercings among metalworkers was not included in the study,” she noted.

The results of the study may not be generalizable to patients in the United States, she added, because regulations and requirements to provide protective gear here may differ.

“Taking a thorough patient history is crucial when investigating potential causes of dermatitis, especially in patients with suspected allergic contact dermatitis,” Dr. Tyler urged.

Funding and conflict-of-interest details were not provided. Dr. Tyler reported no relevant financial relationships.

A version of this article first appeared on Medscape.com.

Contact allergy to cobalt, chromium, and especially nickel, may be higher in European metalworkers than in all European male patients with allergic contact dermatitis, a systematic review and meta-analysis reports.

“Metal allergy to all three metals was significantly more common in European metalworkers with dermatitis attending patch test clinics as compared to ESSCA [European Surveillance System on Contact Allergies] data, indicating a relationship to occupational exposures,” senior study author Jeanne D. Johansen, MD, professor, department of dermatology and allergy, Copenhagen University Hospital, Hellerup, Denmark, and colleagues at the University of Copenhagen wrote in Contact Dermatitis. “However, confounders could not be accounted for.”

How common is metal allergy in metalworkers?

Occupational hand eczema is known to be common in metalworkers. Touching oils, greases, metals, leather gloves, rubber materials, and metalworking fluids as they repeatedly cut, shape, and process raw metals and minerals derived from ore mining exposes metalworkers to allergens and skin irritants, the authors wrote. But the prevalence of allergy to certain metals has not been well characterized.

So they searched PubMed for full-text studies in English that reported metal allergy prevalence in metalworkers, from the database’s inception through April 2022.

They included studies with absolute numbers or proportions of metal allergy to cobalt, chromium, or nickel, in all metalworkers with suspected allergic contact dermatitis who attended outpatient clinics or who worked at metalworking plants participating in workplace studies.

The researchers performed a random-effects meta-analysis to calculate the pooled prevalence of metal allergy. Because 85%-90% of metalworkers in Denmark are male, they compared the estimates they found with ESSCA data on 13,382 consecutively patch-tested males with dermatitis between 2015 and 2018.

Of the 1,667 records they screened, they analyzed data from 29 that met their inclusion criteria: 22 patient studies and 7 workplace studies involving 5,691 patients overall from 22 studies from Europe, 5 studies from Asia, and 1 from Africa. Regarding European metalworkers, the authors found:

• Pooled proportions of allergy in European metalworkers with dermatitis referred to patch test clinics were 8.2% to cobalt (95% confidence interval, 5.3%-11.7%), 8.0% to chromium (95% CI, 5.1%-11.4%), and 11.0% to nickel (95% CI, 7.3%-15.4%).
• In workplace studies, the pooled proportions of allergy in unselected European metalworkers were 4.9% to cobalt, (95% CI, 2.4%-8.1%), 5.2% to chromium (95% CI, 1.0% - 12.6%), and 7.6% to nickel (95% CI, 3.8%-12.6%).
• By comparison, ESSCA data on metal allergy prevalence showed 3.9% allergic to cobalt (95% CI, 3.6%-4.2%), 4.4% allergic to chromium (95% CI, 4.1%-4.8%), and 6.7% allergic to nickel (95% CI, 6.3%-7.0%).
• Data on sex, age, body piercings, and atopic dermatitis were scant.

Thorough histories, protective regulations and equipment

Providers need to ask their dermatitis patients about current and past occupations and hobbies, and employers need to provide employees with equipment that protects them from exposure, Kelly Tyler, MD, associate professor of dermatology, Ohio State University Wexner Medical Center, Columbus, said in an interview.

“Repeated exposure to an allergen is required for sensitization to develop,” said Dr. Tyler, who was not involved in the study. “Metalworkers, who are continually exposed to metals and metalworking fluids, have a higher risk of allergic contact dermatitis to cobalt, chromium, and nickel.”

“The primary treatment for allergic contact dermatitis is preventing continued exposure to the allergen,” she added. “This study highlights the importance of asking about metal or metalworking fluid in the workplace and of elucidating whether the employer is providing appropriate protective gear.”

To prevent occupational dermatitis, workplaces need to apply regulatory measures and provide their employees with protective equipment, Dr. Tyler advised.

“Body piercings are a common sensitizer in patients with metal allergy, and the prevalence of body piercings among metalworkers was not included in the study,” she noted.

The results of the study may not be generalizable to patients in the United States, she added, because regulations and requirements to provide protective gear here may differ.

“Taking a thorough patient history is crucial when investigating potential causes of dermatitis, especially in patients with suspected allergic contact dermatitis,” Dr. Tyler urged.

Funding and conflict-of-interest details were not provided. Dr. Tyler reported no relevant financial relationships.

A version of this article first appeared on Medscape.com.

Contact allergy to cobalt, chromium, and especially nickel, may be higher in European metalworkers than in all European male patients with allergic contact dermatitis, a systematic review and meta-analysis reports.

“Metal allergy to all three metals was significantly more common in European metalworkers with dermatitis attending patch test clinics as compared to ESSCA [European Surveillance System on Contact Allergies] data, indicating a relationship to occupational exposures,” senior study author Jeanne D. Johansen, MD, professor, department of dermatology and allergy, Copenhagen University Hospital, Hellerup, Denmark, and colleagues at the University of Copenhagen wrote in Contact Dermatitis. “However, confounders could not be accounted for.”

How common is metal allergy in metalworkers?

Occupational hand eczema is known to be common in metalworkers. Touching oils, greases, metals, leather gloves, rubber materials, and metalworking fluids as they repeatedly cut, shape, and process raw metals and minerals derived from ore mining exposes metalworkers to allergens and skin irritants, the authors wrote. But the prevalence of allergy to certain metals has not been well characterized.

So they searched PubMed for full-text studies in English that reported metal allergy prevalence in metalworkers, from the database’s inception through April 2022.

They included studies with absolute numbers or proportions of metal allergy to cobalt, chromium, or nickel, in all metalworkers with suspected allergic contact dermatitis who attended outpatient clinics or who worked at metalworking plants participating in workplace studies.

The researchers performed a random-effects meta-analysis to calculate the pooled prevalence of metal allergy. Because 85%-90% of metalworkers in Denmark are male, they compared the estimates they found with ESSCA data on 13,382 consecutively patch-tested males with dermatitis between 2015 and 2018.

Of the 1,667 records they screened, they analyzed data from 29 that met their inclusion criteria: 22 patient studies and 7 workplace studies involving 5,691 patients overall from 22 studies from Europe, 5 studies from Asia, and 1 from Africa. Regarding European metalworkers, the authors found:

• Pooled proportions of allergy in European metalworkers with dermatitis referred to patch test clinics were 8.2% to cobalt (95% confidence interval, 5.3%-11.7%), 8.0% to chromium (95% CI, 5.1%-11.4%), and 11.0% to nickel (95% CI, 7.3%-15.4%).
• In workplace studies, the pooled proportions of allergy in unselected European metalworkers were 4.9% to cobalt, (95% CI, 2.4%-8.1%), 5.2% to chromium (95% CI, 1.0% - 12.6%), and 7.6% to nickel (95% CI, 3.8%-12.6%).
• By comparison, ESSCA data on metal allergy prevalence showed 3.9% allergic to cobalt (95% CI, 3.6%-4.2%), 4.4% allergic to chromium (95% CI, 4.1%-4.8%), and 6.7% allergic to nickel (95% CI, 6.3%-7.0%).
• Data on sex, age, body piercings, and atopic dermatitis were scant.

Thorough histories, protective regulations and equipment

Providers need to ask their dermatitis patients about current and past occupations and hobbies, and employers need to provide employees with equipment that protects them from exposure, Kelly Tyler, MD, associate professor of dermatology, Ohio State University Wexner Medical Center, Columbus, said in an interview.

“Repeated exposure to an allergen is required for sensitization to develop,” said Dr. Tyler, who was not involved in the study. “Metalworkers, who are continually exposed to metals and metalworking fluids, have a higher risk of allergic contact dermatitis to cobalt, chromium, and nickel.”

“The primary treatment for allergic contact dermatitis is preventing continued exposure to the allergen,” she added. “This study highlights the importance of asking about metal or metalworking fluid in the workplace and of elucidating whether the employer is providing appropriate protective gear.”

To prevent occupational dermatitis, workplaces need to apply regulatory measures and provide their employees with protective equipment, Dr. Tyler advised.

“Body piercings are a common sensitizer in patients with metal allergy, and the prevalence of body piercings among metalworkers was not included in the study,” she noted.

The results of the study may not be generalizable to patients in the United States, she added, because regulations and requirements to provide protective gear here may differ.

“Taking a thorough patient history is crucial when investigating potential causes of dermatitis, especially in patients with suspected allergic contact dermatitis,” Dr. Tyler urged.

Funding and conflict-of-interest details were not provided. Dr. Tyler reported no relevant financial relationships.

A version of this article first appeared on Medscape.com.

Apple A. Bodemer, MD, a dermatologist at the University of Wisconsin, Madison, teaches patients how to breathe mindfully. So does Kathy Farah, MD, an integrative family physician who practices in Roberts, Wis.

Mindful breathing is the most basic mind-body skill and one that can help interrupt the itch-scratch cycle and relieve pain, stress, and distress often experienced by children, teens, and adults with dermatologic conditions, they said at the annual Integrative Dermatology Symposium.

“As with any integrative modality, if it’s safe and effective, then let’s use it,” Dr. Farah said in a presentation on the mind-body approach to pain and itch.

“A breathwork session can literally take 1 minute,” said Dr. Bodemer, associate professor of dermatology at the University of Wisconsin and director of an integrative dermatology clinic. Dr. Bodemer, who completed a fellowship in integrative medicine at the Andrew Weil Center for Integrative Medicine at the University of Arizona and sits on the American Board of Integrative Medicine, spoke on a mindfulness panel at the meeting.

Her favorite breathing practice is the “4-7-8” breath taught by Andrew Weil, MD, founder and director of the center. This involves inhaling through the nose for a count of 4, holding for 7, and exhaling through the mouth for a count of 8. “It doesn’t matter how slow or fast, it’s the tempo that matters ... On exhale, squeeze your abs in to engage your core and get air out of your lungs as much as you can,” she said, advising a cycle of three at a time.

A technique known as “square breathing” (breath in 4, hold for 4, breath out for 4, hold for 4) is another helpful technique to “reset the nervous system” said Dr. Farah, who worked for many years in a children’s hospital. With children, she said, “I often do five finger breathing.”

For five finger breathing, the children spread their fingers apart in front of them or on the ground and use the pointer finger of the opposite hand to trace each finger, inhaling while tracing upward, and exhaling while tracing down.

Dr. Farah, associate clinical director of The Center for Mind-Body Medicine in Washington, DC, said her commitment to mindfulness was influenced by a “seminal” study published over 20 years ago showing that patients with moderate to severe psoriasis who used a meditation-based, audiotape-guided stress reduction intervention during phototherapy sessions had more rapid resolution of psoriatic lesions than did patients who didn’t use the mindfulness exercise.

Among more recent findings: A cross-sectional study of 120 adult dermatology patients, published in the British Journal of Dermatology in 2016, assessed skin shame, social anxiety, anxiety, depression, dermatological quality of life, and levels of mindfulness, and found that higher levels of mindfulness were associated with lower levels of psychosocial distress.

Another cross-sectional questionnaire study looked at mindfulness and “itch catastrophizing” in 155 adult patients with atopic dermatitis. Higher levels of a specific facet of mindfulness termed “acting with awareness” were associated with lower levels of itch catastrophizing, the researchers found. “Catastrophizing is a negative way of thinking, this itching will never stop,” Dr. Farah explained. The study shows that “mindfulness can actually help reduce some of the automatic scratching and response to itch. So it’s a great adjunct to pharmaceuticals.”

Affirmations – phrases and statements that are repeated to oneself to help challenge negative thoughts – can also help reverse itch catastrophizing. Statements such as “I can breathe through this feeling of itching,” or “I can move to feel comfortable and relaxed” encourage positive change, she said.

“I teach [mindfulness skills like breathing] a lot, without any expectations. I’ll say ‘give it a try and see what you think.’ If patients feel even a micron better, then they’re invested” and can then find numerous tools online, Dr. Farah said. “Can I do this [in a busy schedule] with every patient? Absolutely not. But can I do it with every 10th patient? Maybe.”

Dr. Bodemer’s experience has shown her that “breathing with your patient builds rapport,” she said. “There’s something very powerful in that in terms of building trust. ... I’ll just do it [during a visit, to show them] and almost always, patients start breathing with me, with an invitation or without.”

For her own health, 4-7-8 breathing has “been a gateway to meditation and deeper practices,” she said. “But even without going very deep, it has a long history of being able to modulate the stress response. It’s the parasympathetic-sympathetic rebalancing I’m interested in.”

Mindful breathing and other mind-body practices also can be helpful for parents of children with eczema, she and Dr. Farah said.

Dr. Bodemer and Dr. Farah reported no financial relationships to disclose.

Apple A. Bodemer, MD, a dermatologist at the University of Wisconsin, Madison, teaches patients how to breathe mindfully. So does Kathy Farah, MD, an integrative family physician who practices in Roberts, Wis.

Mindful breathing is the most basic mind-body skill and one that can help interrupt the itch-scratch cycle and relieve pain, stress, and distress often experienced by children, teens, and adults with dermatologic conditions, they said at the annual Integrative Dermatology Symposium.

“As with any integrative modality, if it’s safe and effective, then let’s use it,” Dr. Farah said in a presentation on the mind-body approach to pain and itch.

“A breathwork session can literally take 1 minute,” said Dr. Bodemer, associate professor of dermatology at the University of Wisconsin and director of an integrative dermatology clinic. Dr. Bodemer, who completed a fellowship in integrative medicine at the Andrew Weil Center for Integrative Medicine at the University of Arizona and sits on the American Board of Integrative Medicine, spoke on a mindfulness panel at the meeting.

Her favorite breathing practice is the “4-7-8” breath taught by Andrew Weil, MD, founder and director of the center. This involves inhaling through the nose for a count of 4, holding for 7, and exhaling through the mouth for a count of 8. “It doesn’t matter how slow or fast, it’s the tempo that matters ... On exhale, squeeze your abs in to engage your core and get air out of your lungs as much as you can,” she said, advising a cycle of three at a time.

A technique known as “square breathing” (breath in 4, hold for 4, breath out for 4, hold for 4) is another helpful technique to “reset the nervous system” said Dr. Farah, who worked for many years in a children’s hospital. With children, she said, “I often do five finger breathing.”

For five finger breathing, the children spread their fingers apart in front of them or on the ground and use the pointer finger of the opposite hand to trace each finger, inhaling while tracing upward, and exhaling while tracing down.

Dr. Farah, associate clinical director of The Center for Mind-Body Medicine in Washington, DC, said her commitment to mindfulness was influenced by a “seminal” study published over 20 years ago showing that patients with moderate to severe psoriasis who used a meditation-based, audiotape-guided stress reduction intervention during phototherapy sessions had more rapid resolution of psoriatic lesions than did patients who didn’t use the mindfulness exercise.

Among more recent findings: A cross-sectional study of 120 adult dermatology patients, published in the British Journal of Dermatology in 2016, assessed skin shame, social anxiety, anxiety, depression, dermatological quality of life, and levels of mindfulness, and found that higher levels of mindfulness were associated with lower levels of psychosocial distress.

Another cross-sectional questionnaire study looked at mindfulness and “itch catastrophizing” in 155 adult patients with atopic dermatitis. Higher levels of a specific facet of mindfulness termed “acting with awareness” were associated with lower levels of itch catastrophizing, the researchers found. “Catastrophizing is a negative way of thinking, this itching will never stop,” Dr. Farah explained. The study shows that “mindfulness can actually help reduce some of the automatic scratching and response to itch. So it’s a great adjunct to pharmaceuticals.”

Affirmations – phrases and statements that are repeated to oneself to help challenge negative thoughts – can also help reverse itch catastrophizing. Statements such as “I can breathe through this feeling of itching,” or “I can move to feel comfortable and relaxed” encourage positive change, she said.

“I teach [mindfulness skills like breathing] a lot, without any expectations. I’ll say ‘give it a try and see what you think.’ If patients feel even a micron better, then they’re invested” and can then find numerous tools online, Dr. Farah said. “Can I do this [in a busy schedule] with every patient? Absolutely not. But can I do it with every 10th patient? Maybe.”

Dr. Bodemer’s experience has shown her that “breathing with your patient builds rapport,” she said. “There’s something very powerful in that in terms of building trust. ... I’ll just do it [during a visit, to show them] and almost always, patients start breathing with me, with an invitation or without.”

For her own health, 4-7-8 breathing has “been a gateway to meditation and deeper practices,” she said. “But even without going very deep, it has a long history of being able to modulate the stress response. It’s the parasympathetic-sympathetic rebalancing I’m interested in.”

Mindful breathing and other mind-body practices also can be helpful for parents of children with eczema, she and Dr. Farah said.

Dr. Bodemer and Dr. Farah reported no financial relationships to disclose.

Apple A. Bodemer, MD, a dermatologist at the University of Wisconsin, Madison, teaches patients how to breathe mindfully. So does Kathy Farah, MD, an integrative family physician who practices in Roberts, Wis.

Mindful breathing is the most basic mind-body skill and one that can help interrupt the itch-scratch cycle and relieve pain, stress, and distress often experienced by children, teens, and adults with dermatologic conditions, they said at the annual Integrative Dermatology Symposium.

“As with any integrative modality, if it’s safe and effective, then let’s use it,” Dr. Farah said in a presentation on the mind-body approach to pain and itch.

“A breathwork session can literally take 1 minute,” said Dr. Bodemer, associate professor of dermatology at the University of Wisconsin and director of an integrative dermatology clinic. Dr. Bodemer, who completed a fellowship in integrative medicine at the Andrew Weil Center for Integrative Medicine at the University of Arizona and sits on the American Board of Integrative Medicine, spoke on a mindfulness panel at the meeting.

Her favorite breathing practice is the “4-7-8” breath taught by Andrew Weil, MD, founder and director of the center. This involves inhaling through the nose for a count of 4, holding for 7, and exhaling through the mouth for a count of 8. “It doesn’t matter how slow or fast, it’s the tempo that matters ... On exhale, squeeze your abs in to engage your core and get air out of your lungs as much as you can,” she said, advising a cycle of three at a time.

A technique known as “square breathing” (breath in 4, hold for 4, breath out for 4, hold for 4) is another helpful technique to “reset the nervous system” said Dr. Farah, who worked for many years in a children’s hospital. With children, she said, “I often do five finger breathing.”

For five finger breathing, the children spread their fingers apart in front of them or on the ground and use the pointer finger of the opposite hand to trace each finger, inhaling while tracing upward, and exhaling while tracing down.

Dr. Farah, associate clinical director of The Center for Mind-Body Medicine in Washington, DC, said her commitment to mindfulness was influenced by a “seminal” study published over 20 years ago showing that patients with moderate to severe psoriasis who used a meditation-based, audiotape-guided stress reduction intervention during phototherapy sessions had more rapid resolution of psoriatic lesions than did patients who didn’t use the mindfulness exercise.

Among more recent findings: A cross-sectional study of 120 adult dermatology patients, published in the British Journal of Dermatology in 2016, assessed skin shame, social anxiety, anxiety, depression, dermatological quality of life, and levels of mindfulness, and found that higher levels of mindfulness were associated with lower levels of psychosocial distress.

Another cross-sectional questionnaire study looked at mindfulness and “itch catastrophizing” in 155 adult patients with atopic dermatitis. Higher levels of a specific facet of mindfulness termed “acting with awareness” were associated with lower levels of itch catastrophizing, the researchers found. “Catastrophizing is a negative way of thinking, this itching will never stop,” Dr. Farah explained. The study shows that “mindfulness can actually help reduce some of the automatic scratching and response to itch. So it’s a great adjunct to pharmaceuticals.”

Affirmations – phrases and statements that are repeated to oneself to help challenge negative thoughts – can also help reverse itch catastrophizing. Statements such as “I can breathe through this feeling of itching,” or “I can move to feel comfortable and relaxed” encourage positive change, she said.

“I teach [mindfulness skills like breathing] a lot, without any expectations. I’ll say ‘give it a try and see what you think.’ If patients feel even a micron better, then they’re invested” and can then find numerous tools online, Dr. Farah said. “Can I do this [in a busy schedule] with every patient? Absolutely not. But can I do it with every 10th patient? Maybe.”

Dr. Bodemer’s experience has shown her that “breathing with your patient builds rapport,” she said. “There’s something very powerful in that in terms of building trust. ... I’ll just do it [during a visit, to show them] and almost always, patients start breathing with me, with an invitation or without.”

For her own health, 4-7-8 breathing has “been a gateway to meditation and deeper practices,” she said. “But even without going very deep, it has a long history of being able to modulate the stress response. It’s the parasympathetic-sympathetic rebalancing I’m interested in.”

Mindful breathing and other mind-body practices also can be helpful for parents of children with eczema, she and Dr. Farah said.

Dr. Bodemer and Dr. Farah reported no financial relationships to disclose.

Reactions to poison ivy, poison oak, and poison sumac, which affect 10 to 50 million Americans a year,¹ are classified as Toxicodendron dermatitis; 50% to 75% of US adults are clinically sensitive to these plants.² Furthermore, people of all ethnicities, skin types, and ages residing in most US geographical regions are at risk.³ Allergenicity is caused by urushiol, which is found in members of the Anacardiaceae family.⁴ Once absorbed, urushiol causes a type IV hypersensitivity reaction in those who are susceptible.⁵

Cutaneous Manifestations

Toxicodendron dermatitis presents with an acute eczematous eruption characterized by streaks of intensely pruritic and erythematous papules and vesicles (Figure 1). Areas of involvement are characterized by sharp margins that follow the pattern of contact made by the plant’s leaves, berries, stems, and vines.⁶ The fluid content of the vesicles is not antigenic and cannot cause subsequent transmission to oneself or others.³ A person with prior contact to the plant who becomes sensitized develops an eruption 24 to 48 hours after subsequent contact with the plant; peak severity manifests 1 to 14 days later.⁷

When left untreated, the eruption can last 3 weeks. If the plant is burned, urushiol can be aerosolized in smoke, causing respiratory tract inflammation and generalized dermatitis, which has been reported among wildland firefighters.² Long-term complications from an outbreak are limited but can include postinflammatory hyperpigmentation and secondary bacterial infection.⁸ Rare reports of nephrotic syndrome also have appeared in the literature.⁹Toxicodendron dermatitis can present distinctively as so-called black dot dermatitis.⁶

Nomenclature

Poison ivy, poison oak, and poison sumac are members of the family Anacardiaceae and genus Toxicodendron,⁶ derived from the Greek words toxikos (poison) and dendron (tree).¹⁰

Distribution

Toxicodendron plants characteristically are found in various regions of the United States. Poison ivy is the most common and is comprised of 2 species: Toxicodendron rydbergii and Toxicodendron radicans. Toxicodendron rydbergii is a nonclimbing dwarf shrub typically found in the northern and western United States. Toxicodendron radicans is a climbing vine found in the eastern United States. Poison oak also is comprised of 2 species—Toxicodendron toxicarium and Toxicodendron diversilobum—and is more common in the western United States. Poison sumac (also known as Toxicodendron vernix) is a small shrub that grows in moist swampy areas. It has a predilection for marshes of the eastern and southeastern United States.^6,11

Identifying Features

Educating patients on how to identify poison ivy can play a key role in avoidance, which is the most important step in preventing Toxicodendron dermatitis. A challenge in identification of poison ivy is the plant’s variable appearance; it grows as a small shrub, low-lying vine, or vine that climbs other trees.

As the vine matures, it develops tiny, rough, “hairy” rootlets—hence the saying, “Hairy vine, no friend of mine!” Rootlets help the plant attach to trees growing near a water source. Vines can reach a diameter of 3 inches. From mature vines, solitary stems extend 1 to 2 inches with 3 characteristic leaves at the terminus (Figure 2), prompting another classic saying, “Leaves of 3, let it be!”¹²

Poison oak is characterized by 3 to 5 leaflets. Poison sumac has 7 to 13 pointed, smooth-edged leaves.⁶

Dermatitis-Inducing Plant Parts

The primary allergenic component of Toxicodendron plants is urushiol, a resinous sap found in stems, roots, leaves, and skins of the fruits. These components must be damaged or bruised to release the allergen; slight contact with an uninjured plant part might not lead to harm.^2,13 Some common forms of transmission include skin contact, ingestion, inhalation of smoke from burning plants, and contact with skin through contaminated items, such as clothing, animals, and tools.¹⁴

Allergens

The catecholic ring and aliphatic chain of the urushiol molecule are allergenic.¹⁵ The degree of saturation and length of the side chains vary with different catechols. Urushiol displays cross-reactivity with poison ivy, poison oak, and poison sumac. Urushiol from these plants differs only slightly in structure; therefore, sensitization to one causes sensitization to all. There also is cross-reactivity between different members of the Anacardiaceae family, including Anacardium occidentale (tropical cashew nut), Mangifera indica (tropical mango tree), Ginkgo biloba (ginkgo tree), and Semecarpus anacardium (Indian marking nut tree).¹²

Poison ivy, poison oak, and poison sumac cause allergic contact dermatitis as a type IV hypersensitivity reaction. First, urushiol binds and penetrates the skin, where it is oxidized to quinone intermediates and bound to haptens. Then, the intermediates bind surface proteins on antigen-presenting cells, specifically Langerhans cells in the epidermis and dermis.⁵

Presentation of nonpeptide antigens, such as urushiol, to T cells requires expression of langerin (also known as CD207) and CD1a.¹⁶ Langerin is a C-type lectin that causes formation of Birbeck granules; CD1a is a major histocompatibility complex class I molecule found in Birbeck granules.^5,17 After Langerhans cells internalize and process the urushiol self-hapten neoantigen, it is presented to CD4⁺ T cells.⁶ These cells then expand to form circulating activated T-effector and T-memory lymphocytes.¹⁸

The molecular link that occurs between the hapten and carrier protein determines the response. When linked by an amino nucleophile, selective induction of T-effector cells ensues, resulting in allergic contact dermatitis. When linked by a sulfhydryl bond, selective induction of suppressor cells occurs, resulting in a reduced allergic contact dermatitis response.¹⁹ In the case of activation of T-effector cells, a cell-mediated cytotoxic immune response is generated that destroys epidermal cells and dermal vasculature.² The incidence and intensity of poison ivy sensitivity decline proportionally with age and the absence of continued exposure.²⁰

Preventive Action—Patients should be counseled that if contact between plant and skin occurs, it is important to remove contaminated clothing or objects and wash them with soap to prevent additional exposure.^14,21 Areas of the skin that made contact with the plant should be washed with water as soon as possible; after 30 minutes, urushiol has sufficiently penetrated to cause a reaction.² Forceful unidirectional washing with a damp washcloth and liquid dishwashing soap is recommended.²²

Several barrier creams are commercially available to help prevent absorption or to deactivate the urushiol antigen. These products are used widely by forestry workers and wildland firefighters.²³ One such barrier cream is bentoquatam (sold as various trade names), an organoclay compound made of quaternium-18 bentonite that interferes with absorption of the allergen by acting as a physical blocker.²⁴

Treatment

After Toxicodendron dermatitis develops, several treatments are available to help manage symptoms. Calamine lotion can be used to help dry weeping lesions.^25,26 Topical steroids can be used to help control pruritus and alleviate inflammation. High-potency topical corticosteroids such as clobetasol and mid-potency steroids such as triamcinolone can be used. Topical anesthetics (eg, benzocaine, pramoxine, benzyl alcohol) might provide symptomatic relief.^27,28

Oral antihistamines can allow for better sleep by providing sedation but do not target the pruritus of poison ivy dermatitis, which is not histamine mediated.^29,30 Systemic corticosteroids usually are considered in more severe dermatitis—when 20% or more of the body surface area is involved; blistering and itching are severe; or the face, hands, or genitalia are involved.^31,32

Clinical Uses

Therapeutic uses for poison ivy have been explored extensively. In 1892, Dakin³³ reported that ingestion of leaves by Native Americans reduced the incidence and severity of skin lesions after contact with poison ivy. Consumption of poison ivy was further studied by Epstein and colleagues³⁴ in 1974; they concluded that ingestion of a large amount of urushiol over a period of 3 months or longer may help with hyposensitization—but not complete desensitization—to contact with poison ivy. However, the risk for adverse effects is thought to outweigh benefits because ingestion can cause perianal dermatitis, mucocutaneous sequelae, and systemic contact dermatitis.²

Although the use of Toxicodendron plants in modern-day medicine is limited, development of a vaccine (immunotherapy) against Toxicodendron dermatitis offers an exciting opportunity for further research.

Reactions to poison ivy, poison oak, and poison sumac, which affect 10 to 50 million Americans a year,¹ are classified as Toxicodendron dermatitis; 50% to 75% of US adults are clinically sensitive to these plants.² Furthermore, people of all ethnicities, skin types, and ages residing in most US geographical regions are at risk.³ Allergenicity is caused by urushiol, which is found in members of the Anacardiaceae family.⁴ Once absorbed, urushiol causes a type IV hypersensitivity reaction in those who are susceptible.⁵

Cutaneous Manifestations

Toxicodendron dermatitis presents with an acute eczematous eruption characterized by streaks of intensely pruritic and erythematous papules and vesicles (Figure 1). Areas of involvement are characterized by sharp margins that follow the pattern of contact made by the plant’s leaves, berries, stems, and vines.⁶ The fluid content of the vesicles is not antigenic and cannot cause subsequent transmission to oneself or others.³ A person with prior contact to the plant who becomes sensitized develops an eruption 24 to 48 hours after subsequent contact with the plant; peak severity manifests 1 to 14 days later.⁷

When left untreated, the eruption can last 3 weeks. If the plant is burned, urushiol can be aerosolized in smoke, causing respiratory tract inflammation and generalized dermatitis, which has been reported among wildland firefighters.² Long-term complications from an outbreak are limited but can include postinflammatory hyperpigmentation and secondary bacterial infection.⁸ Rare reports of nephrotic syndrome also have appeared in the literature.⁹Toxicodendron dermatitis can present distinctively as so-called black dot dermatitis.⁶

Nomenclature

Poison ivy, poison oak, and poison sumac are members of the family Anacardiaceae and genus Toxicodendron,⁶ derived from the Greek words toxikos (poison) and dendron (tree).¹⁰

Distribution

Toxicodendron plants characteristically are found in various regions of the United States. Poison ivy is the most common and is comprised of 2 species: Toxicodendron rydbergii and Toxicodendron radicans. Toxicodendron rydbergii is a nonclimbing dwarf shrub typically found in the northern and western United States. Toxicodendron radicans is a climbing vine found in the eastern United States. Poison oak also is comprised of 2 species—Toxicodendron toxicarium and Toxicodendron diversilobum—and is more common in the western United States. Poison sumac (also known as Toxicodendron vernix) is a small shrub that grows in moist swampy areas. It has a predilection for marshes of the eastern and southeastern United States.^6,11

Identifying Features

Educating patients on how to identify poison ivy can play a key role in avoidance, which is the most important step in preventing Toxicodendron dermatitis. A challenge in identification of poison ivy is the plant’s variable appearance; it grows as a small shrub, low-lying vine, or vine that climbs other trees.

As the vine matures, it develops tiny, rough, “hairy” rootlets—hence the saying, “Hairy vine, no friend of mine!” Rootlets help the plant attach to trees growing near a water source. Vines can reach a diameter of 3 inches. From mature vines, solitary stems extend 1 to 2 inches with 3 characteristic leaves at the terminus (Figure 2), prompting another classic saying, “Leaves of 3, let it be!”¹²

Poison oak is characterized by 3 to 5 leaflets. Poison sumac has 7 to 13 pointed, smooth-edged leaves.⁶

Dermatitis-Inducing Plant Parts

The primary allergenic component of Toxicodendron plants is urushiol, a resinous sap found in stems, roots, leaves, and skins of the fruits. These components must be damaged or bruised to release the allergen; slight contact with an uninjured plant part might not lead to harm.^2,13 Some common forms of transmission include skin contact, ingestion, inhalation of smoke from burning plants, and contact with skin through contaminated items, such as clothing, animals, and tools.¹⁴

Allergens

The catecholic ring and aliphatic chain of the urushiol molecule are allergenic.¹⁵ The degree of saturation and length of the side chains vary with different catechols. Urushiol displays cross-reactivity with poison ivy, poison oak, and poison sumac. Urushiol from these plants differs only slightly in structure; therefore, sensitization to one causes sensitization to all. There also is cross-reactivity between different members of the Anacardiaceae family, including Anacardium occidentale (tropical cashew nut), Mangifera indica (tropical mango tree), Ginkgo biloba (ginkgo tree), and Semecarpus anacardium (Indian marking nut tree).¹²

Poison ivy, poison oak, and poison sumac cause allergic contact dermatitis as a type IV hypersensitivity reaction. First, urushiol binds and penetrates the skin, where it is oxidized to quinone intermediates and bound to haptens. Then, the intermediates bind surface proteins on antigen-presenting cells, specifically Langerhans cells in the epidermis and dermis.⁵

Presentation of nonpeptide antigens, such as urushiol, to T cells requires expression of langerin (also known as CD207) and CD1a.¹⁶ Langerin is a C-type lectin that causes formation of Birbeck granules; CD1a is a major histocompatibility complex class I molecule found in Birbeck granules.^5,17 After Langerhans cells internalize and process the urushiol self-hapten neoantigen, it is presented to CD4⁺ T cells.⁶ These cells then expand to form circulating activated T-effector and T-memory lymphocytes.¹⁸

The molecular link that occurs between the hapten and carrier protein determines the response. When linked by an amino nucleophile, selective induction of T-effector cells ensues, resulting in allergic contact dermatitis. When linked by a sulfhydryl bond, selective induction of suppressor cells occurs, resulting in a reduced allergic contact dermatitis response.¹⁹ In the case of activation of T-effector cells, a cell-mediated cytotoxic immune response is generated that destroys epidermal cells and dermal vasculature.² The incidence and intensity of poison ivy sensitivity decline proportionally with age and the absence of continued exposure.²⁰

Preventive Action—Patients should be counseled that if contact between plant and skin occurs, it is important to remove contaminated clothing or objects and wash them with soap to prevent additional exposure.^14,21 Areas of the skin that made contact with the plant should be washed with water as soon as possible; after 30 minutes, urushiol has sufficiently penetrated to cause a reaction.² Forceful unidirectional washing with a damp washcloth and liquid dishwashing soap is recommended.²²

Several barrier creams are commercially available to help prevent absorption or to deactivate the urushiol antigen. These products are used widely by forestry workers and wildland firefighters.²³ One such barrier cream is bentoquatam (sold as various trade names), an organoclay compound made of quaternium-18 bentonite that interferes with absorption of the allergen by acting as a physical blocker.²⁴

Treatment

After Toxicodendron dermatitis develops, several treatments are available to help manage symptoms. Calamine lotion can be used to help dry weeping lesions.^25,26 Topical steroids can be used to help control pruritus and alleviate inflammation. High-potency topical corticosteroids such as clobetasol and mid-potency steroids such as triamcinolone can be used. Topical anesthetics (eg, benzocaine, pramoxine, benzyl alcohol) might provide symptomatic relief.^27,28

Oral antihistamines can allow for better sleep by providing sedation but do not target the pruritus of poison ivy dermatitis, which is not histamine mediated.^29,30 Systemic corticosteroids usually are considered in more severe dermatitis—when 20% or more of the body surface area is involved; blistering and itching are severe; or the face, hands, or genitalia are involved.^31,32

Clinical Uses

Therapeutic uses for poison ivy have been explored extensively. In 1892, Dakin³³ reported that ingestion of leaves by Native Americans reduced the incidence and severity of skin lesions after contact with poison ivy. Consumption of poison ivy was further studied by Epstein and colleagues³⁴ in 1974; they concluded that ingestion of a large amount of urushiol over a period of 3 months or longer may help with hyposensitization—but not complete desensitization—to contact with poison ivy. However, the risk for adverse effects is thought to outweigh benefits because ingestion can cause perianal dermatitis, mucocutaneous sequelae, and systemic contact dermatitis.²

Although the use of Toxicodendron plants in modern-day medicine is limited, development of a vaccine (immunotherapy) against Toxicodendron dermatitis offers an exciting opportunity for further research.

Reactions to poison ivy, poison oak, and poison sumac, which affect 10 to 50 million Americans a year,¹ are classified as Toxicodendron dermatitis; 50% to 75% of US adults are clinically sensitive to these plants.² Furthermore, people of all ethnicities, skin types, and ages residing in most US geographical regions are at risk.³ Allergenicity is caused by urushiol, which is found in members of the Anacardiaceae family.⁴ Once absorbed, urushiol causes a type IV hypersensitivity reaction in those who are susceptible.⁵

Cutaneous Manifestations

Toxicodendron dermatitis presents with an acute eczematous eruption characterized by streaks of intensely pruritic and erythematous papules and vesicles (Figure 1). Areas of involvement are characterized by sharp margins that follow the pattern of contact made by the plant’s leaves, berries, stems, and vines.⁶ The fluid content of the vesicles is not antigenic and cannot cause subsequent transmission to oneself or others.³ A person with prior contact to the plant who becomes sensitized develops an eruption 24 to 48 hours after subsequent contact with the plant; peak severity manifests 1 to 14 days later.⁷

When left untreated, the eruption can last 3 weeks. If the plant is burned, urushiol can be aerosolized in smoke, causing respiratory tract inflammation and generalized dermatitis, which has been reported among wildland firefighters.² Long-term complications from an outbreak are limited but can include postinflammatory hyperpigmentation and secondary bacterial infection.⁸ Rare reports of nephrotic syndrome also have appeared in the literature.⁹Toxicodendron dermatitis can present distinctively as so-called black dot dermatitis.⁶

Nomenclature

Poison ivy, poison oak, and poison sumac are members of the family Anacardiaceae and genus Toxicodendron,⁶ derived from the Greek words toxikos (poison) and dendron (tree).¹⁰

Distribution

Toxicodendron plants characteristically are found in various regions of the United States. Poison ivy is the most common and is comprised of 2 species: Toxicodendron rydbergii and Toxicodendron radicans. Toxicodendron rydbergii is a nonclimbing dwarf shrub typically found in the northern and western United States. Toxicodendron radicans is a climbing vine found in the eastern United States. Poison oak also is comprised of 2 species—Toxicodendron toxicarium and Toxicodendron diversilobum—and is more common in the western United States. Poison sumac (also known as Toxicodendron vernix) is a small shrub that grows in moist swampy areas. It has a predilection for marshes of the eastern and southeastern United States.^6,11

Identifying Features

Educating patients on how to identify poison ivy can play a key role in avoidance, which is the most important step in preventing Toxicodendron dermatitis. A challenge in identification of poison ivy is the plant’s variable appearance; it grows as a small shrub, low-lying vine, or vine that climbs other trees.

As the vine matures, it develops tiny, rough, “hairy” rootlets—hence the saying, “Hairy vine, no friend of mine!” Rootlets help the plant attach to trees growing near a water source. Vines can reach a diameter of 3 inches. From mature vines, solitary stems extend 1 to 2 inches with 3 characteristic leaves at the terminus (Figure 2), prompting another classic saying, “Leaves of 3, let it be!”¹²

Poison oak is characterized by 3 to 5 leaflets. Poison sumac has 7 to 13 pointed, smooth-edged leaves.⁶

Dermatitis-Inducing Plant Parts

The primary allergenic component of Toxicodendron plants is urushiol, a resinous sap found in stems, roots, leaves, and skins of the fruits. These components must be damaged or bruised to release the allergen; slight contact with an uninjured plant part might not lead to harm.^2,13 Some common forms of transmission include skin contact, ingestion, inhalation of smoke from burning plants, and contact with skin through contaminated items, such as clothing, animals, and tools.¹⁴

Allergens

The catecholic ring and aliphatic chain of the urushiol molecule are allergenic.¹⁵ The degree of saturation and length of the side chains vary with different catechols. Urushiol displays cross-reactivity with poison ivy, poison oak, and poison sumac. Urushiol from these plants differs only slightly in structure; therefore, sensitization to one causes sensitization to all. There also is cross-reactivity between different members of the Anacardiaceae family, including Anacardium occidentale (tropical cashew nut), Mangifera indica (tropical mango tree), Ginkgo biloba (ginkgo tree), and Semecarpus anacardium (Indian marking nut tree).¹²

Poison ivy, poison oak, and poison sumac cause allergic contact dermatitis as a type IV hypersensitivity reaction. First, urushiol binds and penetrates the skin, where it is oxidized to quinone intermediates and bound to haptens. Then, the intermediates bind surface proteins on antigen-presenting cells, specifically Langerhans cells in the epidermis and dermis.⁵

Presentation of nonpeptide antigens, such as urushiol, to T cells requires expression of langerin (also known as CD207) and CD1a.¹⁶ Langerin is a C-type lectin that causes formation of Birbeck granules; CD1a is a major histocompatibility complex class I molecule found in Birbeck granules.^5,17 After Langerhans cells internalize and process the urushiol self-hapten neoantigen, it is presented to CD4⁺ T cells.⁶ These cells then expand to form circulating activated T-effector and T-memory lymphocytes.¹⁸

The molecular link that occurs between the hapten and carrier protein determines the response. When linked by an amino nucleophile, selective induction of T-effector cells ensues, resulting in allergic contact dermatitis. When linked by a sulfhydryl bond, selective induction of suppressor cells occurs, resulting in a reduced allergic contact dermatitis response.¹⁹ In the case of activation of T-effector cells, a cell-mediated cytotoxic immune response is generated that destroys epidermal cells and dermal vasculature.² The incidence and intensity of poison ivy sensitivity decline proportionally with age and the absence of continued exposure.²⁰

Preventive Action—Patients should be counseled that if contact between plant and skin occurs, it is important to remove contaminated clothing or objects and wash them with soap to prevent additional exposure.^14,21 Areas of the skin that made contact with the plant should be washed with water as soon as possible; after 30 minutes, urushiol has sufficiently penetrated to cause a reaction.² Forceful unidirectional washing with a damp washcloth and liquid dishwashing soap is recommended.²²

Several barrier creams are commercially available to help prevent absorption or to deactivate the urushiol antigen. These products are used widely by forestry workers and wildland firefighters.²³ One such barrier cream is bentoquatam (sold as various trade names), an organoclay compound made of quaternium-18 bentonite that interferes with absorption of the allergen by acting as a physical blocker.²⁴

Treatment

After Toxicodendron dermatitis develops, several treatments are available to help manage symptoms. Calamine lotion can be used to help dry weeping lesions.^25,26 Topical steroids can be used to help control pruritus and alleviate inflammation. High-potency topical corticosteroids such as clobetasol and mid-potency steroids such as triamcinolone can be used. Topical anesthetics (eg, benzocaine, pramoxine, benzyl alcohol) might provide symptomatic relief.^27,28

Oral antihistamines can allow for better sleep by providing sedation but do not target the pruritus of poison ivy dermatitis, which is not histamine mediated.^29,30 Systemic corticosteroids usually are considered in more severe dermatitis—when 20% or more of the body surface area is involved; blistering and itching are severe; or the face, hands, or genitalia are involved.^31,32

Clinical Uses

Therapeutic uses for poison ivy have been explored extensively. In 1892, Dakin³³ reported that ingestion of leaves by Native Americans reduced the incidence and severity of skin lesions after contact with poison ivy. Consumption of poison ivy was further studied by Epstein and colleagues³⁴ in 1974; they concluded that ingestion of a large amount of urushiol over a period of 3 months or longer may help with hyposensitization—but not complete desensitization—to contact with poison ivy. However, the risk for adverse effects is thought to outweigh benefits because ingestion can cause perianal dermatitis, mucocutaneous sequelae, and systemic contact dermatitis.²

Although the use of Toxicodendron plants in modern-day medicine is limited, development of a vaccine (immunotherapy) against Toxicodendron dermatitis offers an exciting opportunity for further research.

When compared with the general population, hairdressers experience an excess risk of contact allergy linked to hair cosmetic ingredients, a systematic review suggests.

“Research has shown that up to 70% of hairdressers suffer from work-related skin damage, mostly hand dermatitis, at some point during their career,” write Wolfgang Uter of Friedrich-Alexander University Erlangen-Nürnberg and coauthors. In general, they write, occupational skin diseases such as hand dermatitis represent up to 35% of reported occupational diseases. The study was published online in Contact Dermatitis.

Wet work and skin contact with detergents and hairdressing chemicals are top risk factors for developing occupational skin disease in this population, according to the researchers.

To further understand the burden of occupational contact allergy in hairdressers, the investigators gathered evidence published since 2000 on contact allergies to hair cosmetic chemicals. They searched the literature for nine substances selected beforehand by experts and stakeholders. The researchers also examined the prevalence of sensitization between hairdressers and other individuals given skin patch tests.
 

Substance by substance

Common potentially sensitizing cosmetic ingredients reported across studies included p-phenylenediamine (PPD), persulfates (mostly ammonium persulfate [APS]), glyceryl thioglycolate (GMTG), and ammonium thioglycolate (ATG).

In a pooled analysis, the overall prevalence of contact allergy to PPD was 4.3% in consecutively patch-tested patients, but in hairdressers specifically, the overall prevalence of contact allergy to this ingredient was 28.6%, reviewers reported.

The pooled prevalence of contact allergy to APS was 5.5% in consumers and 17.2% in hairdressers. In other review studies, contact allergy risks to APS, GMTG, and ATG were also elevated in hairdressers compared with all controls.

The calculated relative risk (RR) of contact allergy to PPD was approximately 5.4 higher for hairdressers, while the RR for ATG sensitization was 3.4 in hairdressers compared with consumers.

Commenting on these findings, James A. Yiannias, MD, professor of dermatology at the Mayo Medical School, Phoenix, told this news organization in an email that many providers and patients are concerned only about hair dye molecules such as PPD and aminophenol, as well as permanent, wave, and straightening chemicals such as GMTG.

“Although these are common allergens in hairdressers, allergens such as fragrances and some preservatives found in daily hair care products such as shampoos, conditioners, and hair sprays are also common causes of contact dermatitis,” said Dr. Yiannias, who wasn’t involved in the research.

Consequences of exposure

Dr. Yiannias explained that progressive worsening of the dermatitis can occur with ongoing allergen exposure and, if not properly mitigated, can lead to bigger issues. “Initial nuisances of mild irritation and hyperkeratosis can evolve to a state of fissuring with the risk of bleeding and significant pain,” he said.

But once severe and untreated dermatitis occurs, Dr. Yiannias said that hairdressers “may need to change careers” or at least face short- or long-term unemployment.

The researchers suggest reducing exposure to the allergen is key for prevention of symptoms, adding that adequate guidance on the safe use of new products is needed. Also, the researchers suggested that vocational schools should more rigorously implement education for hairdressers that addresses how to protect the skin appropriately at work.

“Hairdressers are taught during their training to be cautious about allergen exposure by avoiding touching high-risk ingredients such as hair dyes,” Dr. Yiannias added. “However, in practice, this is very difficult since the wearing of gloves can impair the tactile sensations that hairdressers often feel is essential in performing their job.”

The study received no industry funding. Dr. Yiannias reports no relevant financial relationships.

A version of this article first appeared on Medscape.com.

When compared with the general population, hairdressers experience an excess risk of contact allergy linked to hair cosmetic ingredients, a systematic review suggests.

“Research has shown that up to 70% of hairdressers suffer from work-related skin damage, mostly hand dermatitis, at some point during their career,” write Wolfgang Uter of Friedrich-Alexander University Erlangen-Nürnberg and coauthors. In general, they write, occupational skin diseases such as hand dermatitis represent up to 35% of reported occupational diseases. The study was published online in Contact Dermatitis.

Wet work and skin contact with detergents and hairdressing chemicals are top risk factors for developing occupational skin disease in this population, according to the researchers.

To further understand the burden of occupational contact allergy in hairdressers, the investigators gathered evidence published since 2000 on contact allergies to hair cosmetic chemicals. They searched the literature for nine substances selected beforehand by experts and stakeholders. The researchers also examined the prevalence of sensitization between hairdressers and other individuals given skin patch tests.
 

Substance by substance

Common potentially sensitizing cosmetic ingredients reported across studies included p-phenylenediamine (PPD), persulfates (mostly ammonium persulfate [APS]), glyceryl thioglycolate (GMTG), and ammonium thioglycolate (ATG).

In a pooled analysis, the overall prevalence of contact allergy to PPD was 4.3% in consecutively patch-tested patients, but in hairdressers specifically, the overall prevalence of contact allergy to this ingredient was 28.6%, reviewers reported.

The pooled prevalence of contact allergy to APS was 5.5% in consumers and 17.2% in hairdressers. In other review studies, contact allergy risks to APS, GMTG, and ATG were also elevated in hairdressers compared with all controls.

The calculated relative risk (RR) of contact allergy to PPD was approximately 5.4 higher for hairdressers, while the RR for ATG sensitization was 3.4 in hairdressers compared with consumers.

Commenting on these findings, James A. Yiannias, MD, professor of dermatology at the Mayo Medical School, Phoenix, told this news organization in an email that many providers and patients are concerned only about hair dye molecules such as PPD and aminophenol, as well as permanent, wave, and straightening chemicals such as GMTG.

“Although these are common allergens in hairdressers, allergens such as fragrances and some preservatives found in daily hair care products such as shampoos, conditioners, and hair sprays are also common causes of contact dermatitis,” said Dr. Yiannias, who wasn’t involved in the research.

Consequences of exposure

Dr. Yiannias explained that progressive worsening of the dermatitis can occur with ongoing allergen exposure and, if not properly mitigated, can lead to bigger issues. “Initial nuisances of mild irritation and hyperkeratosis can evolve to a state of fissuring with the risk of bleeding and significant pain,” he said.

But once severe and untreated dermatitis occurs, Dr. Yiannias said that hairdressers “may need to change careers” or at least face short- or long-term unemployment.

The researchers suggest reducing exposure to the allergen is key for prevention of symptoms, adding that adequate guidance on the safe use of new products is needed. Also, the researchers suggested that vocational schools should more rigorously implement education for hairdressers that addresses how to protect the skin appropriately at work.

“Hairdressers are taught during their training to be cautious about allergen exposure by avoiding touching high-risk ingredients such as hair dyes,” Dr. Yiannias added. “However, in practice, this is very difficult since the wearing of gloves can impair the tactile sensations that hairdressers often feel is essential in performing their job.”

The study received no industry funding. Dr. Yiannias reports no relevant financial relationships.

A version of this article first appeared on Medscape.com.

When compared with the general population, hairdressers experience an excess risk of contact allergy linked to hair cosmetic ingredients, a systematic review suggests.

“Research has shown that up to 70% of hairdressers suffer from work-related skin damage, mostly hand dermatitis, at some point during their career,” write Wolfgang Uter of Friedrich-Alexander University Erlangen-Nürnberg and coauthors. In general, they write, occupational skin diseases such as hand dermatitis represent up to 35% of reported occupational diseases. The study was published online in Contact Dermatitis.

Wet work and skin contact with detergents and hairdressing chemicals are top risk factors for developing occupational skin disease in this population, according to the researchers.

To further understand the burden of occupational contact allergy in hairdressers, the investigators gathered evidence published since 2000 on contact allergies to hair cosmetic chemicals. They searched the literature for nine substances selected beforehand by experts and stakeholders. The researchers also examined the prevalence of sensitization between hairdressers and other individuals given skin patch tests.
 

Substance by substance

Common potentially sensitizing cosmetic ingredients reported across studies included p-phenylenediamine (PPD), persulfates (mostly ammonium persulfate [APS]), glyceryl thioglycolate (GMTG), and ammonium thioglycolate (ATG).

In a pooled analysis, the overall prevalence of contact allergy to PPD was 4.3% in consecutively patch-tested patients, but in hairdressers specifically, the overall prevalence of contact allergy to this ingredient was 28.6%, reviewers reported.

The pooled prevalence of contact allergy to APS was 5.5% in consumers and 17.2% in hairdressers. In other review studies, contact allergy risks to APS, GMTG, and ATG were also elevated in hairdressers compared with all controls.

The calculated relative risk (RR) of contact allergy to PPD was approximately 5.4 higher for hairdressers, while the RR for ATG sensitization was 3.4 in hairdressers compared with consumers.

Commenting on these findings, James A. Yiannias, MD, professor of dermatology at the Mayo Medical School, Phoenix, told this news organization in an email that many providers and patients are concerned only about hair dye molecules such as PPD and aminophenol, as well as permanent, wave, and straightening chemicals such as GMTG.

“Although these are common allergens in hairdressers, allergens such as fragrances and some preservatives found in daily hair care products such as shampoos, conditioners, and hair sprays are also common causes of contact dermatitis,” said Dr. Yiannias, who wasn’t involved in the research.

Consequences of exposure

Dr. Yiannias explained that progressive worsening of the dermatitis can occur with ongoing allergen exposure and, if not properly mitigated, can lead to bigger issues. “Initial nuisances of mild irritation and hyperkeratosis can evolve to a state of fissuring with the risk of bleeding and significant pain,” he said.

But once severe and untreated dermatitis occurs, Dr. Yiannias said that hairdressers “may need to change careers” or at least face short- or long-term unemployment.

The researchers suggest reducing exposure to the allergen is key for prevention of symptoms, adding that adequate guidance on the safe use of new products is needed. Also, the researchers suggested that vocational schools should more rigorously implement education for hairdressers that addresses how to protect the skin appropriately at work.

“Hairdressers are taught during their training to be cautious about allergen exposure by avoiding touching high-risk ingredients such as hair dyes,” Dr. Yiannias added. “However, in practice, this is very difficult since the wearing of gloves can impair the tactile sensations that hairdressers often feel is essential in performing their job.”

The study received no industry funding. Dr. Yiannias reports no relevant financial relationships.

A version of this article first appeared on Medscape.com.

Photoallergic contact dermatitis (PACD), a subtype of allergic contact dermatitis that occurs because of the specific combination of exposure to an exogenous chemical applied topically to the skin and UV radiation, may be more common than was once thought.¹ Although the incidence in the general population is unknown, current research points to approximately 20% to 40% of patients with suspected photosensitivity having a PACD diagnosis.² Recently, the North American Contact Dermatitis Group (NACDG) reported that 21% of 373 patients undergoing photopatch testing (PPT) were diagnosed with PACD²; however, PPT is not routinely performed, which may contribute to underdiagnosis.

Mechanism of Disease

Similar to allergic contact dermatitis, PACD is a delayed type IV hypersensitivity reaction; however, it only occurs when an exogenous chemical is applied topically to the skin with concomitant exposure to UV radiation, usually in the UVA range (315–400 nm).^3,4 When exposed to UV radiation, it is thought that the exogenous chemical combines with a protein in the skin and transforms into a photoantigen. In the sensitization phase, the photoantigen is taken up by antigen-presenting cells in the epidermis and transported to local lymph nodes where antigen-specific T cells are generated.⁵ In the elicitation phase, the inflammatory reaction of PACD occurs upon subsequent exposure to the same chemical plus UV radiation.⁴ Development of PACD does not necessarily depend on the dose of the chemical or the amount of UV radiation.⁶ Why certain individuals may be more susceptible is unknown, though major histocompatibility complex haplotypes could be influential.^7,8

Clinical Manifestations

Photoallergic contact dermatitis primarily presents in sun-exposed areas of the skin (eg, face, neck, V area of the chest, dorsal upper extremities) with sparing of naturally photoprotected sites, such as the upper eyelids and nasolabial and retroauricular folds. Other than its characteristic photodistribution, PACD often is clinically indistinguishable from routine allergic contact dermatitis. It manifests as a pruritic, poorly demarcated, eczematous or sometimes vesiculobullous eruption that develops in a delayed fashion—24 to 72 hours after sun exposure. The dermatitis may extend to other parts of the body either through spread of the chemical agent by the hands or clothing or due to the systemic nature of the immune response. The severity of the presentation can vary depending on multiple factors, such as concentration and absorption of the agent, length of exposure, intensity and duration of UV radiation exposure, and individual susceptibility.⁴ Chronic PACD may become lichenified. Generally, rashes resolve after discontinuation of the causative agent; however, long-term exposure may lead to development of chronic actinic dermatitis, with persistent photodistributed eczema regardless of contact with the initial inciting agent.⁹

Differential Diagnosis

The differential diagnosis for patients presenting with photodistributed dermatitis is broad; therefore, taking a thorough history is important. Considerations include age of onset, timing and persistence of reactions, use of topical and systemic medications (both prescription and over-the-counter [OTC]), personal care products, occupation, and hobbies, as well as a thorough review of systems.

It is important to distinguish PACD from phototoxic contact dermatitis (PTCD)(also known as photoirritant contact dermatitis)(Table). Asking about the onset and timing of the eruption may be critical for distinction, as PTCD can occur within minutes to hours of the first exposure to a chemical and UV radiation, while there is a sensitization delay in PACD.⁶ Phytophotodermatitis is a well-known type of PTCD caused by exposure to furocoumarin-containing plants, most commonly limes.¹⁰ Other causes of PTCD include tar products and certain medications.¹¹ Importantly, PPT to a known phototoxic chemical should never be performed because it will cause a strong reaction in anyone tested, regardless of exposure history.

Diagnosis

Histologically, PACD presents similarly to allergic contact dermatitis with spongiotic dermatitis; therefore, biopsy cannot be relied upon to make the diagnosis.⁶ Photopatch testing is required for definitive diagnosis. It is reasonable to perform PPT in any patient with chronic dermatitis primarily affecting sun-exposed areas without a clear alternative diagnosis.^14,15 Of note, at present there are no North American consensus guidelines for PPT, but typically duplicate sets of photoallergens are applied to both sides of the patient’s back and one side is exposed to UVA radiation. The reactions are compared after 48 to 96 hours.¹⁵ A positive reaction only at the irradiated site is consistent with photoallergy, while a reaction of equal strength at both the irradiated and nonirradiated sites indicates regular contact allergy. The case of a reaction occurring at both sites with a stronger response at the irradiated site is known as photoaggravated contact allergy, which can be thought of as allergic contact dermatitis that worsens but does not solely occur with exposure to sunlight.

Although PPT is necessary for the accurate diagnosis of PACD, it is infrequently used. Two surveys of 112 and 117 American Contact Dermatitis Society members, respectively, have revealed that only around half performed PPT, most of them testing fewer than 20 times per year.^16,17 Additionally, there was variability in the test methodology and allergens employed. Nevertheless, most respondents tested sunscreens, nonsteroidal anti-inflammatory drugs (NSAIDs), fragrances, and their patients’ own products.^16,17 The most common reasons for not performing PPT were lack of equipment, insufficient skills, rare clinical suspicion, and cost. Dermatologists at academic centers performed more PPT than those in other practice settings, including multispecialty group practices and private offices.¹⁶ These findings highlight multiple factors that may contribute to reduced patient access to PPT and thus potential underdiagnosis of PACD.

Common Photoallergens

The most common photoallergens change over time in response to market trends; for example, fragrance was once a top photoallergen in the United States in the 1970s and 1980s but declined in prominence after musk ambrette—the primary allergen associated with PACD at the time—was removed as an ingredient in fragrances.¹⁸

In the largest and most recent PPT series from North America (1999-2009),² sunscreens comprised 7 of the top 10 most common photoallergens, which is consistent with other studies showing sunscreens to be the most common North American photoallergens.^19-22 The frequency of PACD due to sunscreens likely relates to their increasing use worldwide as awareness of photocarcinogenesis and photoaging grows, as well as the common use of UV filters in nonsunscreen personal care products, ranging from lip balms to perfumes and bodywashes. Chemical (organic) UV filters—in particular oxybenzone (benzophenone-3) and avobenzone (butyl methoxydibenzoylmethane)—are the most common sunscreen photoallergens.^2,23 Para-aminobenzoic acid was once a common photoallergen, but it is no longer used in US sunscreens due to safety concerns.^19,20 The physical (inorganic) UV filters zinc oxide and titanium dioxide are not known photosensitizers.

Methylisothiazolinone (MI) is a highly allergenic preservative commonly used in a wide array of personal care products, including sunscreens.²⁴ In the most recent NACDG patch test data, MI was the second most common contact allergen.²⁵ Allergic contact dermatitis caused by MI in sunscreen can mimic PACD.²⁶ In addition, MI can cause photoaggravated contact dermatitis, with some affected patients experiencing ongoing photosensitivity even after avoiding this allergen.^26-30 The European Union and Canada have introduced restrictions on the use of MI in personal care products, but no such regulatory measures have been taken in the United States to date.^25,31,32

After sunscreens, another common cause of PACD are topical NSAIDs, which are frequently used for musculoskeletal pain relief. These are of particular concern in Europe, where a variety of formulations are widely available OTC.³³ Ketoprofen and etofenamate are responsible for the largest number of PACD reactions in Europe.^2,34,35 Meanwhile, the only OTC topical NSAID available in the United States is diclofenac gel, which was approved in 2020. Cases of PACD due to use of diclofenac gel have been reported in the literature, but testing in larger populations is needed.^36-39

Notably, ketoprofen may co- or cross-react with certain UV filters—oxybenzone and octocrylene—and the lipid-lowering agent fenofibrate due to chemical similarities.^40-43 Despite the relatively high number of photoallergic reactions to ketoprofen in the NACDG photopatch series, only 25% (5/20) were considered clinically relevant (ie, the allergen could not be verified as present in the known skin contactants of the patient, and the patient was not exposed to circumstances in which contact with materials known to contain the allergen would likely occur), which suggests that they likely represented cross-reactions in patients sensitized to sunscreens.²

Other agents that may cause PACD include antimicrobials, plants and plant derivatives, and pesticides.^2,4,18 The antimicrobial fentichlor is a common cause of positive PPT reactions, but it rarely is clinically relevant.⁴⁴

Treatment

The primary management of PACD centers on identification of the causative photoallergen to avoid future exposure. Patients should be educated on the various names by which the causative allergen can be identified on product labels and should be given a list of safe products that are free from relevant allergens and cross-reacting chemicals.⁴⁵ Additionally, sun protection education should be provided. Exposure to UVA radiation can occur through windows, making the use of broad-spectrum sunscreens and protective clothing crucial. In cases of sunscreen-induced PACD, the responsible chemical UV filter(s) should be avoided, or alternatively, patients may use physical sunscreens containing only zinc oxide and/or titanium dioxide as active ingredients, as these are not known to cause PACD.⁴

When avoidance alone is insufficient, topical corticosteroids are the usual first-line treatment for localized PACD. When steroid-sparing treatments are preferred, topical calcineurin inhibitors such as tacrolimus and pimecrolimus may be used. If PACD is more widespread and severe, systemic therapy using steroids or steroid-sparing agents may be necessary to provide symptomatic relief.⁴

Final Interpretation

Photoallergic contact dermatitis is not uncommon, particularly among photosensitive patients. Most cases are due to sunscreens or topical NSAIDs. Consideration of PPT should be given in any patient with a chronic photodistributed dermatitis to evaluate for the possibility of PACD.

Photoallergic contact dermatitis (PACD), a subtype of allergic contact dermatitis that occurs because of the specific combination of exposure to an exogenous chemical applied topically to the skin and UV radiation, may be more common than was once thought.¹ Although the incidence in the general population is unknown, current research points to approximately 20% to 40% of patients with suspected photosensitivity having a PACD diagnosis.² Recently, the North American Contact Dermatitis Group (NACDG) reported that 21% of 373 patients undergoing photopatch testing (PPT) were diagnosed with PACD²; however, PPT is not routinely performed, which may contribute to underdiagnosis.

Mechanism of Disease

Similar to allergic contact dermatitis, PACD is a delayed type IV hypersensitivity reaction; however, it only occurs when an exogenous chemical is applied topically to the skin with concomitant exposure to UV radiation, usually in the UVA range (315–400 nm).^3,4 When exposed to UV radiation, it is thought that the exogenous chemical combines with a protein in the skin and transforms into a photoantigen. In the sensitization phase, the photoantigen is taken up by antigen-presenting cells in the epidermis and transported to local lymph nodes where antigen-specific T cells are generated.⁵ In the elicitation phase, the inflammatory reaction of PACD occurs upon subsequent exposure to the same chemical plus UV radiation.⁴ Development of PACD does not necessarily depend on the dose of the chemical or the amount of UV radiation.⁶ Why certain individuals may be more susceptible is unknown, though major histocompatibility complex haplotypes could be influential.^7,8

Clinical Manifestations

Photoallergic contact dermatitis primarily presents in sun-exposed areas of the skin (eg, face, neck, V area of the chest, dorsal upper extremities) with sparing of naturally photoprotected sites, such as the upper eyelids and nasolabial and retroauricular folds. Other than its characteristic photodistribution, PACD often is clinically indistinguishable from routine allergic contact dermatitis. It manifests as a pruritic, poorly demarcated, eczematous or sometimes vesiculobullous eruption that develops in a delayed fashion—24 to 72 hours after sun exposure. The dermatitis may extend to other parts of the body either through spread of the chemical agent by the hands or clothing or due to the systemic nature of the immune response. The severity of the presentation can vary depending on multiple factors, such as concentration and absorption of the agent, length of exposure, intensity and duration of UV radiation exposure, and individual susceptibility.⁴ Chronic PACD may become lichenified. Generally, rashes resolve after discontinuation of the causative agent; however, long-term exposure may lead to development of chronic actinic dermatitis, with persistent photodistributed eczema regardless of contact with the initial inciting agent.⁹

Differential Diagnosis

The differential diagnosis for patients presenting with photodistributed dermatitis is broad; therefore, taking a thorough history is important. Considerations include age of onset, timing and persistence of reactions, use of topical and systemic medications (both prescription and over-the-counter [OTC]), personal care products, occupation, and hobbies, as well as a thorough review of systems.

It is important to distinguish PACD from phototoxic contact dermatitis (PTCD)(also known as photoirritant contact dermatitis)(Table). Asking about the onset and timing of the eruption may be critical for distinction, as PTCD can occur within minutes to hours of the first exposure to a chemical and UV radiation, while there is a sensitization delay in PACD.⁶ Phytophotodermatitis is a well-known type of PTCD caused by exposure to furocoumarin-containing plants, most commonly limes.¹⁰ Other causes of PTCD include tar products and certain medications.¹¹ Importantly, PPT to a known phototoxic chemical should never be performed because it will cause a strong reaction in anyone tested, regardless of exposure history.

Diagnosis

Histologically, PACD presents similarly to allergic contact dermatitis with spongiotic dermatitis; therefore, biopsy cannot be relied upon to make the diagnosis.⁶ Photopatch testing is required for definitive diagnosis. It is reasonable to perform PPT in any patient with chronic dermatitis primarily affecting sun-exposed areas without a clear alternative diagnosis.^14,15 Of note, at present there are no North American consensus guidelines for PPT, but typically duplicate sets of photoallergens are applied to both sides of the patient’s back and one side is exposed to UVA radiation. The reactions are compared after 48 to 96 hours.¹⁵ A positive reaction only at the irradiated site is consistent with photoallergy, while a reaction of equal strength at both the irradiated and nonirradiated sites indicates regular contact allergy. The case of a reaction occurring at both sites with a stronger response at the irradiated site is known as photoaggravated contact allergy, which can be thought of as allergic contact dermatitis that worsens but does not solely occur with exposure to sunlight.

Although PPT is necessary for the accurate diagnosis of PACD, it is infrequently used. Two surveys of 112 and 117 American Contact Dermatitis Society members, respectively, have revealed that only around half performed PPT, most of them testing fewer than 20 times per year.^16,17 Additionally, there was variability in the test methodology and allergens employed. Nevertheless, most respondents tested sunscreens, nonsteroidal anti-inflammatory drugs (NSAIDs), fragrances, and their patients’ own products.^16,17 The most common reasons for not performing PPT were lack of equipment, insufficient skills, rare clinical suspicion, and cost. Dermatologists at academic centers performed more PPT than those in other practice settings, including multispecialty group practices and private offices.¹⁶ These findings highlight multiple factors that may contribute to reduced patient access to PPT and thus potential underdiagnosis of PACD.

Common Photoallergens

The most common photoallergens change over time in response to market trends; for example, fragrance was once a top photoallergen in the United States in the 1970s and 1980s but declined in prominence after musk ambrette—the primary allergen associated with PACD at the time—was removed as an ingredient in fragrances.¹⁸

In the largest and most recent PPT series from North America (1999-2009),² sunscreens comprised 7 of the top 10 most common photoallergens, which is consistent with other studies showing sunscreens to be the most common North American photoallergens.^19-22 The frequency of PACD due to sunscreens likely relates to their increasing use worldwide as awareness of photocarcinogenesis and photoaging grows, as well as the common use of UV filters in nonsunscreen personal care products, ranging from lip balms to perfumes and bodywashes. Chemical (organic) UV filters—in particular oxybenzone (benzophenone-3) and avobenzone (butyl methoxydibenzoylmethane)—are the most common sunscreen photoallergens.^2,23 Para-aminobenzoic acid was once a common photoallergen, but it is no longer used in US sunscreens due to safety concerns.^19,20 The physical (inorganic) UV filters zinc oxide and titanium dioxide are not known photosensitizers.

Methylisothiazolinone (MI) is a highly allergenic preservative commonly used in a wide array of personal care products, including sunscreens.²⁴ In the most recent NACDG patch test data, MI was the second most common contact allergen.²⁵ Allergic contact dermatitis caused by MI in sunscreen can mimic PACD.²⁶ In addition, MI can cause photoaggravated contact dermatitis, with some affected patients experiencing ongoing photosensitivity even after avoiding this allergen.^26-30 The European Union and Canada have introduced restrictions on the use of MI in personal care products, but no such regulatory measures have been taken in the United States to date.^25,31,32

After sunscreens, another common cause of PACD are topical NSAIDs, which are frequently used for musculoskeletal pain relief. These are of particular concern in Europe, where a variety of formulations are widely available OTC.³³ Ketoprofen and etofenamate are responsible for the largest number of PACD reactions in Europe.^2,34,35 Meanwhile, the only OTC topical NSAID available in the United States is diclofenac gel, which was approved in 2020. Cases of PACD due to use of diclofenac gel have been reported in the literature, but testing in larger populations is needed.^36-39

Notably, ketoprofen may co- or cross-react with certain UV filters—oxybenzone and octocrylene—and the lipid-lowering agent fenofibrate due to chemical similarities.^40-43 Despite the relatively high number of photoallergic reactions to ketoprofen in the NACDG photopatch series, only 25% (5/20) were considered clinically relevant (ie, the allergen could not be verified as present in the known skin contactants of the patient, and the patient was not exposed to circumstances in which contact with materials known to contain the allergen would likely occur), which suggests that they likely represented cross-reactions in patients sensitized to sunscreens.²

Other agents that may cause PACD include antimicrobials, plants and plant derivatives, and pesticides.^2,4,18 The antimicrobial fentichlor is a common cause of positive PPT reactions, but it rarely is clinically relevant.⁴⁴

Treatment

The primary management of PACD centers on identification of the causative photoallergen to avoid future exposure. Patients should be educated on the various names by which the causative allergen can be identified on product labels and should be given a list of safe products that are free from relevant allergens and cross-reacting chemicals.⁴⁵ Additionally, sun protection education should be provided. Exposure to UVA radiation can occur through windows, making the use of broad-spectrum sunscreens and protective clothing crucial. In cases of sunscreen-induced PACD, the responsible chemical UV filter(s) should be avoided, or alternatively, patients may use physical sunscreens containing only zinc oxide and/or titanium dioxide as active ingredients, as these are not known to cause PACD.⁴

When avoidance alone is insufficient, topical corticosteroids are the usual first-line treatment for localized PACD. When steroid-sparing treatments are preferred, topical calcineurin inhibitors such as tacrolimus and pimecrolimus may be used. If PACD is more widespread and severe, systemic therapy using steroids or steroid-sparing agents may be necessary to provide symptomatic relief.⁴

Final Interpretation

Photoallergic contact dermatitis is not uncommon, particularly among photosensitive patients. Most cases are due to sunscreens or topical NSAIDs. Consideration of PPT should be given in any patient with a chronic photodistributed dermatitis to evaluate for the possibility of PACD.

Photoallergic contact dermatitis (PACD), a subtype of allergic contact dermatitis that occurs because of the specific combination of exposure to an exogenous chemical applied topically to the skin and UV radiation, may be more common than was once thought.¹ Although the incidence in the general population is unknown, current research points to approximately 20% to 40% of patients with suspected photosensitivity having a PACD diagnosis.² Recently, the North American Contact Dermatitis Group (NACDG) reported that 21% of 373 patients undergoing photopatch testing (PPT) were diagnosed with PACD²; however, PPT is not routinely performed, which may contribute to underdiagnosis.

Mechanism of Disease

Similar to allergic contact dermatitis, PACD is a delayed type IV hypersensitivity reaction; however, it only occurs when an exogenous chemical is applied topically to the skin with concomitant exposure to UV radiation, usually in the UVA range (315–400 nm).^3,4 When exposed to UV radiation, it is thought that the exogenous chemical combines with a protein in the skin and transforms into a photoantigen. In the sensitization phase, the photoantigen is taken up by antigen-presenting cells in the epidermis and transported to local lymph nodes where antigen-specific T cells are generated.⁵ In the elicitation phase, the inflammatory reaction of PACD occurs upon subsequent exposure to the same chemical plus UV radiation.⁴ Development of PACD does not necessarily depend on the dose of the chemical or the amount of UV radiation.⁶ Why certain individuals may be more susceptible is unknown, though major histocompatibility complex haplotypes could be influential.^7,8

Clinical Manifestations

Photoallergic contact dermatitis primarily presents in sun-exposed areas of the skin (eg, face, neck, V area of the chest, dorsal upper extremities) with sparing of naturally photoprotected sites, such as the upper eyelids and nasolabial and retroauricular folds. Other than its characteristic photodistribution, PACD often is clinically indistinguishable from routine allergic contact dermatitis. It manifests as a pruritic, poorly demarcated, eczematous or sometimes vesiculobullous eruption that develops in a delayed fashion—24 to 72 hours after sun exposure. The dermatitis may extend to other parts of the body either through spread of the chemical agent by the hands or clothing or due to the systemic nature of the immune response. The severity of the presentation can vary depending on multiple factors, such as concentration and absorption of the agent, length of exposure, intensity and duration of UV radiation exposure, and individual susceptibility.⁴ Chronic PACD may become lichenified. Generally, rashes resolve after discontinuation of the causative agent; however, long-term exposure may lead to development of chronic actinic dermatitis, with persistent photodistributed eczema regardless of contact with the initial inciting agent.⁹

Differential Diagnosis

The differential diagnosis for patients presenting with photodistributed dermatitis is broad; therefore, taking a thorough history is important. Considerations include age of onset, timing and persistence of reactions, use of topical and systemic medications (both prescription and over-the-counter [OTC]), personal care products, occupation, and hobbies, as well as a thorough review of systems.

It is important to distinguish PACD from phototoxic contact dermatitis (PTCD)(also known as photoirritant contact dermatitis)(Table). Asking about the onset and timing of the eruption may be critical for distinction, as PTCD can occur within minutes to hours of the first exposure to a chemical and UV radiation, while there is a sensitization delay in PACD.⁶ Phytophotodermatitis is a well-known type of PTCD caused by exposure to furocoumarin-containing plants, most commonly limes.¹⁰ Other causes of PTCD include tar products and certain medications.¹¹ Importantly, PPT to a known phototoxic chemical should never be performed because it will cause a strong reaction in anyone tested, regardless of exposure history.

Diagnosis

Histologically, PACD presents similarly to allergic contact dermatitis with spongiotic dermatitis; therefore, biopsy cannot be relied upon to make the diagnosis.⁶ Photopatch testing is required for definitive diagnosis. It is reasonable to perform PPT in any patient with chronic dermatitis primarily affecting sun-exposed areas without a clear alternative diagnosis.^14,15 Of note, at present there are no North American consensus guidelines for PPT, but typically duplicate sets of photoallergens are applied to both sides of the patient’s back and one side is exposed to UVA radiation. The reactions are compared after 48 to 96 hours.¹⁵ A positive reaction only at the irradiated site is consistent with photoallergy, while a reaction of equal strength at both the irradiated and nonirradiated sites indicates regular contact allergy. The case of a reaction occurring at both sites with a stronger response at the irradiated site is known as photoaggravated contact allergy, which can be thought of as allergic contact dermatitis that worsens but does not solely occur with exposure to sunlight.

Although PPT is necessary for the accurate diagnosis of PACD, it is infrequently used. Two surveys of 112 and 117 American Contact Dermatitis Society members, respectively, have revealed that only around half performed PPT, most of them testing fewer than 20 times per year.^16,17 Additionally, there was variability in the test methodology and allergens employed. Nevertheless, most respondents tested sunscreens, nonsteroidal anti-inflammatory drugs (NSAIDs), fragrances, and their patients’ own products.^16,17 The most common reasons for not performing PPT were lack of equipment, insufficient skills, rare clinical suspicion, and cost. Dermatologists at academic centers performed more PPT than those in other practice settings, including multispecialty group practices and private offices.¹⁶ These findings highlight multiple factors that may contribute to reduced patient access to PPT and thus potential underdiagnosis of PACD.

Common Photoallergens

The most common photoallergens change over time in response to market trends; for example, fragrance was once a top photoallergen in the United States in the 1970s and 1980s but declined in prominence after musk ambrette—the primary allergen associated with PACD at the time—was removed as an ingredient in fragrances.¹⁸

In the largest and most recent PPT series from North America (1999-2009),² sunscreens comprised 7 of the top 10 most common photoallergens, which is consistent with other studies showing sunscreens to be the most common North American photoallergens.^19-22 The frequency of PACD due to sunscreens likely relates to their increasing use worldwide as awareness of photocarcinogenesis and photoaging grows, as well as the common use of UV filters in nonsunscreen personal care products, ranging from lip balms to perfumes and bodywashes. Chemical (organic) UV filters—in particular oxybenzone (benzophenone-3) and avobenzone (butyl methoxydibenzoylmethane)—are the most common sunscreen photoallergens.^2,23 Para-aminobenzoic acid was once a common photoallergen, but it is no longer used in US sunscreens due to safety concerns.^19,20 The physical (inorganic) UV filters zinc oxide and titanium dioxide are not known photosensitizers.

Methylisothiazolinone (MI) is a highly allergenic preservative commonly used in a wide array of personal care products, including sunscreens.²⁴ In the most recent NACDG patch test data, MI was the second most common contact allergen.²⁵ Allergic contact dermatitis caused by MI in sunscreen can mimic PACD.²⁶ In addition, MI can cause photoaggravated contact dermatitis, with some affected patients experiencing ongoing photosensitivity even after avoiding this allergen.^26-30 The European Union and Canada have introduced restrictions on the use of MI in personal care products, but no such regulatory measures have been taken in the United States to date.^25,31,32

After sunscreens, another common cause of PACD are topical NSAIDs, which are frequently used for musculoskeletal pain relief. These are of particular concern in Europe, where a variety of formulations are widely available OTC.³³ Ketoprofen and etofenamate are responsible for the largest number of PACD reactions in Europe.^2,34,35 Meanwhile, the only OTC topical NSAID available in the United States is diclofenac gel, which was approved in 2020. Cases of PACD due to use of diclofenac gel have been reported in the literature, but testing in larger populations is needed.^36-39

Notably, ketoprofen may co- or cross-react with certain UV filters—oxybenzone and octocrylene—and the lipid-lowering agent fenofibrate due to chemical similarities.^40-43 Despite the relatively high number of photoallergic reactions to ketoprofen in the NACDG photopatch series, only 25% (5/20) were considered clinically relevant (ie, the allergen could not be verified as present in the known skin contactants of the patient, and the patient was not exposed to circumstances in which contact with materials known to contain the allergen would likely occur), which suggests that they likely represented cross-reactions in patients sensitized to sunscreens.²

Other agents that may cause PACD include antimicrobials, plants and plant derivatives, and pesticides.^2,4,18 The antimicrobial fentichlor is a common cause of positive PPT reactions, but it rarely is clinically relevant.⁴⁴

Treatment

The primary management of PACD centers on identification of the causative photoallergen to avoid future exposure. Patients should be educated on the various names by which the causative allergen can be identified on product labels and should be given a list of safe products that are free from relevant allergens and cross-reacting chemicals.⁴⁵ Additionally, sun protection education should be provided. Exposure to UVA radiation can occur through windows, making the use of broad-spectrum sunscreens and protective clothing crucial. In cases of sunscreen-induced PACD, the responsible chemical UV filter(s) should be avoided, or alternatively, patients may use physical sunscreens containing only zinc oxide and/or titanium dioxide as active ingredients, as these are not known to cause PACD.⁴

When avoidance alone is insufficient, topical corticosteroids are the usual first-line treatment for localized PACD. When steroid-sparing treatments are preferred, topical calcineurin inhibitors such as tacrolimus and pimecrolimus may be used. If PACD is more widespread and severe, systemic therapy using steroids or steroid-sparing agents may be necessary to provide symptomatic relief.⁴

Final Interpretation

Photoallergic contact dermatitis is not uncommon, particularly among photosensitive patients. Most cases are due to sunscreens or topical NSAIDs. Consideration of PPT should be given in any patient with a chronic photodistributed dermatitis to evaluate for the possibility of PACD.

A skin protection training program for hairdressers may reduce the risk of hand eczema, new data suggest.

The study was conducted in Denmark, where about 40% of hairdressers develop occupational hand eczema (OHE), according to researchers. Hairdressers globally are exposed to wet work and myriad skin irritants and allergens, including dyes, permanent-wave solutions, persulfates, preservatives, and fragrances. The study, which was funded by the Danish hairdressers and beauticians union, was published in Contact Dermatitis.

Lead author Martin Havmose, BSc, of the National Allergy Research Center, department of dermatology and allergy, University of Copenhagen, Hellerup, Denmark, and colleagues wrote that prevention is critical, inasmuch as eczema can cut careers short and have lasting health effects.

Up to 70% of hairdressers experience some sort of work-related skin damage in their careers, as reported by this news organization.

Hand eczema also is common among hairdressers in the United States, Mark Denis Davis, MD, chair of dermatology at the Mayo Clinic in Rochester, Minn., told this news organization. It can be quite debilitating, itchy, and painful, he said.

“Often it is associated with painful fissuring, cracks in the skin, particularly involving the fingers. It may also be unsightly,” he said.

Dr. Davis said he hears anecdotally in his practice that many hairdressers are reluctant to wear gloves because of the touch and dexterity needed in their work.

The researchers evaluated the risk of OHE and compliance with skin protection measures among hairdressers who were trained before Denmark rolled out a nationwide skin protection program in hairdressing vocational schools in 2011.

Questionnaires were sent in May 2009 to all hairdressers (96.4% women; average age, 26) who had graduated from 1985 to 2007; in May 2020, questionnaires were sent to all hairdressers who had graduated from 2008 to 2018.

The average time worked in the trade was 8 years, and 28.8% no longer worked as hairdressers, data show.

The response rate was 66.6% (305/460) for the 2009 survey and 29.9% (363/1215) for the 2020 survey.
 

Prevalence of OHE dropped after program

The prevalence of OHE during career time dropped from 42.8% to 29% (adjusted odds ratio, 0.55; 95% confidence interval [CI], 0.40-0.77) between the two surveys.

In addition, the incidence rate of OHE decreased from 57.5 (95% CI, 48.4-68.4) to 42.0 (95% CI, 34.6-50.9) per 1,000 person-years (incidence rate ratio, 0.73; 95% CI, 0.560.95) in that period.

There was an increase in the use of gloves between the two surveys. There was more glove use when the hairdressers engaged in wet work and handled dyes, products with bleach, and permanent-wave solutions (P < .05).

The nationwide program educates hairdressing apprentices on contact allergy/urticaria, how to prevent occupational skin disease, and skin biology. Teaching materials focus on 11 recommendations, 7 of which are related to glove use.

“The lack of primary prevention of OHE in hairdressing vocational schools may be a missed opportunity in the prevention of the disease,” the authors concluded.

Dr. Davis said hairdressers with hand eczema should know that in the short term, topical corticosteroids can be used to decrease the inflammation of the skin.

He highlighted the following advice from the authors:

• Gloves should be used when washing, dyeing, bleaching, and creating perms.
• Disposable gloves should never be reused.
• Gloves should be used only as long as necessary.
• Rings should not be worn at work.
• Cotton gloves should be worn underneath protective gloves.
• For clients who are having their hair both cut and dyed, the hair should be cut before it is dyed.
• Nitrile gloves should be used without rubber accelerators.

“In the longer term,” said Dr. Davis, “the most important thing is to avoid exposure to the precipitating factors, such as wet work – working with water, which irritates the skin – and avoiding any allergens that are contributing to the eczema.”

The study was funded by an unrestricted grant from the Danish hairdressers and beauticians union. Two coauthors have links to industry, as listed in the original article. Dr. Davis reports no relevant financial relationships.

A version of this article first appeared on Medscape.com.

A skin protection training program for hairdressers may reduce the risk of hand eczema, new data suggest.

The study was conducted in Denmark, where about 40% of hairdressers develop occupational hand eczema (OHE), according to researchers. Hairdressers globally are exposed to wet work and myriad skin irritants and allergens, including dyes, permanent-wave solutions, persulfates, preservatives, and fragrances. The study, which was funded by the Danish hairdressers and beauticians union, was published in Contact Dermatitis.

Lead author Martin Havmose, BSc, of the National Allergy Research Center, department of dermatology and allergy, University of Copenhagen, Hellerup, Denmark, and colleagues wrote that prevention is critical, inasmuch as eczema can cut careers short and have lasting health effects.

Up to 70% of hairdressers experience some sort of work-related skin damage in their careers, as reported by this news organization.

Hand eczema also is common among hairdressers in the United States, Mark Denis Davis, MD, chair of dermatology at the Mayo Clinic in Rochester, Minn., told this news organization. It can be quite debilitating, itchy, and painful, he said.

“Often it is associated with painful fissuring, cracks in the skin, particularly involving the fingers. It may also be unsightly,” he said.

Dr. Davis said he hears anecdotally in his practice that many hairdressers are reluctant to wear gloves because of the touch and dexterity needed in their work.

The researchers evaluated the risk of OHE and compliance with skin protection measures among hairdressers who were trained before Denmark rolled out a nationwide skin protection program in hairdressing vocational schools in 2011.

Questionnaires were sent in May 2009 to all hairdressers (96.4% women; average age, 26) who had graduated from 1985 to 2007; in May 2020, questionnaires were sent to all hairdressers who had graduated from 2008 to 2018.

The average time worked in the trade was 8 years, and 28.8% no longer worked as hairdressers, data show.

The response rate was 66.6% (305/460) for the 2009 survey and 29.9% (363/1215) for the 2020 survey.
 

Prevalence of OHE dropped after program

The prevalence of OHE during career time dropped from 42.8% to 29% (adjusted odds ratio, 0.55; 95% confidence interval [CI], 0.40-0.77) between the two surveys.

In addition, the incidence rate of OHE decreased from 57.5 (95% CI, 48.4-68.4) to 42.0 (95% CI, 34.6-50.9) per 1,000 person-years (incidence rate ratio, 0.73; 95% CI, 0.560.95) in that period.

There was an increase in the use of gloves between the two surveys. There was more glove use when the hairdressers engaged in wet work and handled dyes, products with bleach, and permanent-wave solutions (P < .05).

The nationwide program educates hairdressing apprentices on contact allergy/urticaria, how to prevent occupational skin disease, and skin biology. Teaching materials focus on 11 recommendations, 7 of which are related to glove use.

“The lack of primary prevention of OHE in hairdressing vocational schools may be a missed opportunity in the prevention of the disease,” the authors concluded.

Dr. Davis said hairdressers with hand eczema should know that in the short term, topical corticosteroids can be used to decrease the inflammation of the skin.

He highlighted the following advice from the authors:

• Gloves should be used when washing, dyeing, bleaching, and creating perms.
• Disposable gloves should never be reused.
• Gloves should be used only as long as necessary.
• Rings should not be worn at work.
• Cotton gloves should be worn underneath protective gloves.
• For clients who are having their hair both cut and dyed, the hair should be cut before it is dyed.
• Nitrile gloves should be used without rubber accelerators.

“In the longer term,” said Dr. Davis, “the most important thing is to avoid exposure to the precipitating factors, such as wet work – working with water, which irritates the skin – and avoiding any allergens that are contributing to the eczema.”

The study was funded by an unrestricted grant from the Danish hairdressers and beauticians union. Two coauthors have links to industry, as listed in the original article. Dr. Davis reports no relevant financial relationships.

A version of this article first appeared on Medscape.com.

A skin protection training program for hairdressers may reduce the risk of hand eczema, new data suggest.

The study was conducted in Denmark, where about 40% of hairdressers develop occupational hand eczema (OHE), according to researchers. Hairdressers globally are exposed to wet work and myriad skin irritants and allergens, including dyes, permanent-wave solutions, persulfates, preservatives, and fragrances. The study, which was funded by the Danish hairdressers and beauticians union, was published in Contact Dermatitis.

Lead author Martin Havmose, BSc, of the National Allergy Research Center, department of dermatology and allergy, University of Copenhagen, Hellerup, Denmark, and colleagues wrote that prevention is critical, inasmuch as eczema can cut careers short and have lasting health effects.

Up to 70% of hairdressers experience some sort of work-related skin damage in their careers, as reported by this news organization.

Hand eczema also is common among hairdressers in the United States, Mark Denis Davis, MD, chair of dermatology at the Mayo Clinic in Rochester, Minn., told this news organization. It can be quite debilitating, itchy, and painful, he said.

“Often it is associated with painful fissuring, cracks in the skin, particularly involving the fingers. It may also be unsightly,” he said.

Dr. Davis said he hears anecdotally in his practice that many hairdressers are reluctant to wear gloves because of the touch and dexterity needed in their work.

The researchers evaluated the risk of OHE and compliance with skin protection measures among hairdressers who were trained before Denmark rolled out a nationwide skin protection program in hairdressing vocational schools in 2011.

Questionnaires were sent in May 2009 to all hairdressers (96.4% women; average age, 26) who had graduated from 1985 to 2007; in May 2020, questionnaires were sent to all hairdressers who had graduated from 2008 to 2018.

The average time worked in the trade was 8 years, and 28.8% no longer worked as hairdressers, data show.

The response rate was 66.6% (305/460) for the 2009 survey and 29.9% (363/1215) for the 2020 survey.
 

Prevalence of OHE dropped after program

The prevalence of OHE during career time dropped from 42.8% to 29% (adjusted odds ratio, 0.55; 95% confidence interval [CI], 0.40-0.77) between the two surveys.

In addition, the incidence rate of OHE decreased from 57.5 (95% CI, 48.4-68.4) to 42.0 (95% CI, 34.6-50.9) per 1,000 person-years (incidence rate ratio, 0.73; 95% CI, 0.560.95) in that period.

There was an increase in the use of gloves between the two surveys. There was more glove use when the hairdressers engaged in wet work and handled dyes, products with bleach, and permanent-wave solutions (P < .05).

The nationwide program educates hairdressing apprentices on contact allergy/urticaria, how to prevent occupational skin disease, and skin biology. Teaching materials focus on 11 recommendations, 7 of which are related to glove use.

“The lack of primary prevention of OHE in hairdressing vocational schools may be a missed opportunity in the prevention of the disease,” the authors concluded.

Dr. Davis said hairdressers with hand eczema should know that in the short term, topical corticosteroids can be used to decrease the inflammation of the skin.

He highlighted the following advice from the authors:

• Gloves should be used when washing, dyeing, bleaching, and creating perms.
• Disposable gloves should never be reused.
• Gloves should be used only as long as necessary.
• Rings should not be worn at work.
• Cotton gloves should be worn underneath protective gloves.
• For clients who are having their hair both cut and dyed, the hair should be cut before it is dyed.
• Nitrile gloves should be used without rubber accelerators.

“In the longer term,” said Dr. Davis, “the most important thing is to avoid exposure to the precipitating factors, such as wet work – working with water, which irritates the skin – and avoiding any allergens that are contributing to the eczema.”

The study was funded by an unrestricted grant from the Danish hairdressers and beauticians union. Two coauthors have links to industry, as listed in the original article. Dr. Davis reports no relevant financial relationships.

A version of this article first appeared on Medscape.com.

A new guideline aims to help primary care doctors differentiate pollen food syndrome (PFS) – a cross-reactive allergic reaction to certain raw, but not cooked, plant foods – from other food allergies.

The guideline from the British Society of Allergy and Clinical Immunology (BSACI) focuses on birch tree pollen, the major sensitizing PFS allergen in Northern Europe. Providers may be able to diagnose PFS related to birch pollen from clinical history alone, including the foods involved and the rapidity of symptom onset, write lead author Isabel J. Skypala, PhD, RD, of Imperial College London, and her colleagues.

The new BSACI guideline for diagnosis and management of PFS was published in Clinical & Experimental Allergy.
 

PFS is common and increasingly prevalent

PFS – also called oral allergy syndrome and pollen food allergy syndrome – is common and increasingly prevalent. PFS can begin at any age but usually starts in pollen-sensitized school-age children and adults with seasonal allergic rhinitis.

Symptoms from similar proteins in food

Mild to moderate allergic symptoms develop quickly when people sensitized to birch pollen eat raw plant foods that contain proteins similar to those in the pollen, such as pathogenesis-related protein PR-10. The allergens are broken down by cooking or processing.

Symptoms usually occur immediately or within 15 minutes of eating. Patients may have tingling; itching or soreness in the mouth, throat, or ears; mild lip and oral mucosa angioedema; itchy hands, sneezing, or eye symptoms; tongue or pharynx angioedema; perioral rash; cough; abdominal pain; nausea; and/or worsening of eczema. In children, itch and rash may predominate.
 

Triggers depend on pollen type

PFS triggers vary depending on a person’s pollen sensitization, which is affected by their geographic area and local dietary habits. In the United Kingdom, almost 70% of birch-allergic adults and more than 40% of birch-allergic children have PFS, the authors write.

Typical triggers include eating apples, stone fruits, kiwis, carrots, celery, hazelnuts, almonds, walnuts, soymilk, and peanuts, as well as peeling potatoes or other root vegetables. Freshly prepared vegetable or fruit smoothies or juices, celery, soymilk, raw nuts, large quantities of roasted nuts, and concentrated nut products can cause more severe reactions.
 

Diagnostic clinical history

If a patient answers yes to these questions, they almost certainly have PFS, the authors write:

• Are symptoms caused by raw fruits, nuts, carrots, or celery?
• Are the same trigger foods tolerated when they’re cooked well or roasted?
• Do symptoms come immediately or within a few minutes of eating?
• Do symptoms occur in the oropharynx and include tingling, itching, or swelling?
• Does the patient have seasonal allergic rhinitis or sensitization to pollen?

Testing needed for some cases

Allergy tests may be needed for people who report atypical or severe reactions or who also react to cooked or processed plant foods, such as roasted nuts, nuts in foods, fruits or vegetables in juices and smoothies, and soy products other than milk. Tests may also be needed for people who react to foods that are not linked with PFS, such as cashews, pistachios, macadamias, sesame seeds, beans, lentils, and chickpeas.

Whether PFS reactions also occur to roasted hazelnuts, almonds, walnuts, Brazil nuts, or peanuts, either alone or in composite foods such as chocolates, spreads, desserts, and snacks, is unclear.

An oral food challenge to confirm PFS is needed only if the history and diagnostic tests are inconclusive or if the patient is avoiding multiple foods.
 

Dietary management

PFS is managed by excluding known trigger foods. This becomes challenging for patients with preexisting food allergies and for vegetarians and vegans.

Personalized dietary advice is needed to avoid nutritional imbalance, minimize anxiety and unnecessary food restrictions, and improve quality of life. Reactions after accidental exposure often resolve without medication, and if antihistamines are needed, they rarely require self-injectable devices.
 

Guideline helpful beyond the United Kingdom and birch pollen

Allyson S. Larkin, MD, associate professor of pediatrics at the University of Pittsburgh School of Medicine, told this news organization in an email that the guideline summarizes in great detail the pathophysiology behind PFS and highlights how component testing may help diagnose patients and manage the condition.

“Patients worry very much about the progression and severity of allergic reactions,” said Dr. Larkin, who was not involved in the guideline development.

“As the authors note, recognizing the nutritional consequences of dietary restrictions is important, and nutrition consults and suitable alternative suggestions are very helpful for these patients, especially for those with food allergy or who are vegetarian or vegan.”

Jill A. Poole, MD, professor of medicine and chief of the Division of Allergy and Immunology at the University of Nebraska College of Medicine, Omaha, noted that PFS, although common, is underrecognized by the public and by health care providers.

“People are not allergic to the specific food, but they are allergic to a seasonal allergen, such as birch tree, that cross-reacts with the food protein, which is typically changed with cooking,” she explained in an email.

“This differs from reactions by those who have moderate to severe allergic food-specific reactions that may include systemic reactions like anaphylaxis from eating certain foods,” she said.

“Importantly, the number of cross-reacting foods with seasonal pollens continues to grow, and the extent of testing has expanded in recent years,” advised Dr. Poole, who also was not involved in the guideline development. 

The authors recommend further related research into food immunotherapy and other novel PFS treatments. They also want to raise awareness of factors affecting PFS prevalence, such as increased spread and allergenicity of pollen due to climate change, pollution, the global consumption of previously local traditional foods, and the increase in vegetarian and vegan diets.

The authors, Dr. Larkin, and Dr. Poole report no relevant financial relationships involving this guideline. The guideline was not funded.

A version of this article first appeared on Medscape.com.

A new guideline aims to help primary care doctors differentiate pollen food syndrome (PFS) – a cross-reactive allergic reaction to certain raw, but not cooked, plant foods – from other food allergies.

The guideline from the British Society of Allergy and Clinical Immunology (BSACI) focuses on birch tree pollen, the major sensitizing PFS allergen in Northern Europe. Providers may be able to diagnose PFS related to birch pollen from clinical history alone, including the foods involved and the rapidity of symptom onset, write lead author Isabel J. Skypala, PhD, RD, of Imperial College London, and her colleagues.

The new BSACI guideline for diagnosis and management of PFS was published in Clinical & Experimental Allergy.
 

PFS is common and increasingly prevalent

PFS – also called oral allergy syndrome and pollen food allergy syndrome – is common and increasingly prevalent. PFS can begin at any age but usually starts in pollen-sensitized school-age children and adults with seasonal allergic rhinitis.

Symptoms from similar proteins in food

Mild to moderate allergic symptoms develop quickly when people sensitized to birch pollen eat raw plant foods that contain proteins similar to those in the pollen, such as pathogenesis-related protein PR-10. The allergens are broken down by cooking or processing.

Symptoms usually occur immediately or within 15 minutes of eating. Patients may have tingling; itching or soreness in the mouth, throat, or ears; mild lip and oral mucosa angioedema; itchy hands, sneezing, or eye symptoms; tongue or pharynx angioedema; perioral rash; cough; abdominal pain; nausea; and/or worsening of eczema. In children, itch and rash may predominate.
 

Triggers depend on pollen type

PFS triggers vary depending on a person’s pollen sensitization, which is affected by their geographic area and local dietary habits. In the United Kingdom, almost 70% of birch-allergic adults and more than 40% of birch-allergic children have PFS, the authors write.

Typical triggers include eating apples, stone fruits, kiwis, carrots, celery, hazelnuts, almonds, walnuts, soymilk, and peanuts, as well as peeling potatoes or other root vegetables. Freshly prepared vegetable or fruit smoothies or juices, celery, soymilk, raw nuts, large quantities of roasted nuts, and concentrated nut products can cause more severe reactions.
 

Diagnostic clinical history

If a patient answers yes to these questions, they almost certainly have PFS, the authors write:

• Are symptoms caused by raw fruits, nuts, carrots, or celery?
• Are the same trigger foods tolerated when they’re cooked well or roasted?
• Do symptoms come immediately or within a few minutes of eating?
• Do symptoms occur in the oropharynx and include tingling, itching, or swelling?
• Does the patient have seasonal allergic rhinitis or sensitization to pollen?

Testing needed for some cases

Allergy tests may be needed for people who report atypical or severe reactions or who also react to cooked or processed plant foods, such as roasted nuts, nuts in foods, fruits or vegetables in juices and smoothies, and soy products other than milk. Tests may also be needed for people who react to foods that are not linked with PFS, such as cashews, pistachios, macadamias, sesame seeds, beans, lentils, and chickpeas.

Whether PFS reactions also occur to roasted hazelnuts, almonds, walnuts, Brazil nuts, or peanuts, either alone or in composite foods such as chocolates, spreads, desserts, and snacks, is unclear.

An oral food challenge to confirm PFS is needed only if the history and diagnostic tests are inconclusive or if the patient is avoiding multiple foods.
 

Dietary management

PFS is managed by excluding known trigger foods. This becomes challenging for patients with preexisting food allergies and for vegetarians and vegans.

Personalized dietary advice is needed to avoid nutritional imbalance, minimize anxiety and unnecessary food restrictions, and improve quality of life. Reactions after accidental exposure often resolve without medication, and if antihistamines are needed, they rarely require self-injectable devices.
 

Guideline helpful beyond the United Kingdom and birch pollen

Allyson S. Larkin, MD, associate professor of pediatrics at the University of Pittsburgh School of Medicine, told this news organization in an email that the guideline summarizes in great detail the pathophysiology behind PFS and highlights how component testing may help diagnose patients and manage the condition.

“Patients worry very much about the progression and severity of allergic reactions,” said Dr. Larkin, who was not involved in the guideline development.

“As the authors note, recognizing the nutritional consequences of dietary restrictions is important, and nutrition consults and suitable alternative suggestions are very helpful for these patients, especially for those with food allergy or who are vegetarian or vegan.”

Jill A. Poole, MD, professor of medicine and chief of the Division of Allergy and Immunology at the University of Nebraska College of Medicine, Omaha, noted that PFS, although common, is underrecognized by the public and by health care providers.

“People are not allergic to the specific food, but they are allergic to a seasonal allergen, such as birch tree, that cross-reacts with the food protein, which is typically changed with cooking,” she explained in an email.

“This differs from reactions by those who have moderate to severe allergic food-specific reactions that may include systemic reactions like anaphylaxis from eating certain foods,” she said.

“Importantly, the number of cross-reacting foods with seasonal pollens continues to grow, and the extent of testing has expanded in recent years,” advised Dr. Poole, who also was not involved in the guideline development. 

The authors recommend further related research into food immunotherapy and other novel PFS treatments. They also want to raise awareness of factors affecting PFS prevalence, such as increased spread and allergenicity of pollen due to climate change, pollution, the global consumption of previously local traditional foods, and the increase in vegetarian and vegan diets.

The authors, Dr. Larkin, and Dr. Poole report no relevant financial relationships involving this guideline. The guideline was not funded.

A version of this article first appeared on Medscape.com.

A new guideline aims to help primary care doctors differentiate pollen food syndrome (PFS) – a cross-reactive allergic reaction to certain raw, but not cooked, plant foods – from other food allergies.

The guideline from the British Society of Allergy and Clinical Immunology (BSACI) focuses on birch tree pollen, the major sensitizing PFS allergen in Northern Europe. Providers may be able to diagnose PFS related to birch pollen from clinical history alone, including the foods involved and the rapidity of symptom onset, write lead author Isabel J. Skypala, PhD, RD, of Imperial College London, and her colleagues.

The new BSACI guideline for diagnosis and management of PFS was published in Clinical & Experimental Allergy.
 

PFS is common and increasingly prevalent

PFS – also called oral allergy syndrome and pollen food allergy syndrome – is common and increasingly prevalent. PFS can begin at any age but usually starts in pollen-sensitized school-age children and adults with seasonal allergic rhinitis.

Symptoms from similar proteins in food

Mild to moderate allergic symptoms develop quickly when people sensitized to birch pollen eat raw plant foods that contain proteins similar to those in the pollen, such as pathogenesis-related protein PR-10. The allergens are broken down by cooking or processing.

Symptoms usually occur immediately or within 15 minutes of eating. Patients may have tingling; itching or soreness in the mouth, throat, or ears; mild lip and oral mucosa angioedema; itchy hands, sneezing, or eye symptoms; tongue or pharynx angioedema; perioral rash; cough; abdominal pain; nausea; and/or worsening of eczema. In children, itch and rash may predominate.
 

Triggers depend on pollen type

PFS triggers vary depending on a person’s pollen sensitization, which is affected by their geographic area and local dietary habits. In the United Kingdom, almost 70% of birch-allergic adults and more than 40% of birch-allergic children have PFS, the authors write.

Typical triggers include eating apples, stone fruits, kiwis, carrots, celery, hazelnuts, almonds, walnuts, soymilk, and peanuts, as well as peeling potatoes or other root vegetables. Freshly prepared vegetable or fruit smoothies or juices, celery, soymilk, raw nuts, large quantities of roasted nuts, and concentrated nut products can cause more severe reactions.
 

Diagnostic clinical history

If a patient answers yes to these questions, they almost certainly have PFS, the authors write:

• Are symptoms caused by raw fruits, nuts, carrots, or celery?
• Are the same trigger foods tolerated when they’re cooked well or roasted?
• Do symptoms come immediately or within a few minutes of eating?
• Do symptoms occur in the oropharynx and include tingling, itching, or swelling?
• Does the patient have seasonal allergic rhinitis or sensitization to pollen?

Testing needed for some cases

Allergy tests may be needed for people who report atypical or severe reactions or who also react to cooked or processed plant foods, such as roasted nuts, nuts in foods, fruits or vegetables in juices and smoothies, and soy products other than milk. Tests may also be needed for people who react to foods that are not linked with PFS, such as cashews, pistachios, macadamias, sesame seeds, beans, lentils, and chickpeas.

Whether PFS reactions also occur to roasted hazelnuts, almonds, walnuts, Brazil nuts, or peanuts, either alone or in composite foods such as chocolates, spreads, desserts, and snacks, is unclear.

An oral food challenge to confirm PFS is needed only if the history and diagnostic tests are inconclusive or if the patient is avoiding multiple foods.
 

Dietary management

PFS is managed by excluding known trigger foods. This becomes challenging for patients with preexisting food allergies and for vegetarians and vegans.

Personalized dietary advice is needed to avoid nutritional imbalance, minimize anxiety and unnecessary food restrictions, and improve quality of life. Reactions after accidental exposure often resolve without medication, and if antihistamines are needed, they rarely require self-injectable devices.
 

Guideline helpful beyond the United Kingdom and birch pollen

Allyson S. Larkin, MD, associate professor of pediatrics at the University of Pittsburgh School of Medicine, told this news organization in an email that the guideline summarizes in great detail the pathophysiology behind PFS and highlights how component testing may help diagnose patients and manage the condition.

“Patients worry very much about the progression and severity of allergic reactions,” said Dr. Larkin, who was not involved in the guideline development.

“As the authors note, recognizing the nutritional consequences of dietary restrictions is important, and nutrition consults and suitable alternative suggestions are very helpful for these patients, especially for those with food allergy or who are vegetarian or vegan.”

Jill A. Poole, MD, professor of medicine and chief of the Division of Allergy and Immunology at the University of Nebraska College of Medicine, Omaha, noted that PFS, although common, is underrecognized by the public and by health care providers.

“People are not allergic to the specific food, but they are allergic to a seasonal allergen, such as birch tree, that cross-reacts with the food protein, which is typically changed with cooking,” she explained in an email.

“This differs from reactions by those who have moderate to severe allergic food-specific reactions that may include systemic reactions like anaphylaxis from eating certain foods,” she said.

“Importantly, the number of cross-reacting foods with seasonal pollens continues to grow, and the extent of testing has expanded in recent years,” advised Dr. Poole, who also was not involved in the guideline development. 

The authors recommend further related research into food immunotherapy and other novel PFS treatments. They also want to raise awareness of factors affecting PFS prevalence, such as increased spread and allergenicity of pollen due to climate change, pollution, the global consumption of previously local traditional foods, and the increase in vegetarian and vegan diets.

The authors, Dr. Larkin, and Dr. Poole report no relevant financial relationships involving this guideline. The guideline was not funded.

A version of this article first appeared on Medscape.com.

Even with recent pharmacologic treatment advances, narrowband UVB (NB-UVB) phototherapy remains a versatile, safe, and efficacious adjunctive or exclusive treatment for multiple dermatologic conditions, including psoriasis and atopic dermatitis. ^1-9 Some providers choose NB-UVB phototherapy as a first-line treatment for older adult patients who frequently use multiple treatment modalities for more than 1 health condition. Older adults with atopic dermatitis and psoriasis are at higher risk for comorbidities such as autoimmune disorders, diabetes mellitus, dyslipidemia, sleep disorders, neuropsychiatric disorders, and cardiovascular disease that can complicate treatment compared with their peers without these dermatologic diagnoses. ^10-12 Polypharmacy (ie, the use of 5 or more daily medications), frequently associated with these conditions, contributes to prescribers pursuing NB-UVB phototherapy as a nonpharmacologic treatment, but some providers wonder if it is as effective and safe for their older patients compared with younger patients.

In a prior study, Matthews et al¹³ reported that 96% (50/52) of patients older than 65 years achieved medium to high levels of clearance with NB-UVB phototherapy. Nonetheless, 2 other findings in this study related to the number of treatments required to achieve clearance (ie, clearance rates) and erythema rates prompted further investigation. The first finding was higher-than-expected clearance rates. Older adults had a clearance rate with a mean of 33 treatments compared to prior studies featuring mean clearance rates of 20 to 28 treatments.^7,8,14-16 This finding resembled a study in the United Kingdom¹⁷ with a median clearance rate in older adults of 30 treatments. In contrast, the median clearance rate from a study in Turkey¹⁸ was 42 treatments in older adults. We hypothesized that more photosensitizing medications used in older vs younger adults prompted more dose adjustments with NB-UVB phototherapy to avoid burning (ie, erythema) at baseline and throughout the treatment course. These dose adjustments may have increased the overall clearance rates. If true, we predicted that younger adults treated with the same protocol would have cleared more quickly, either because of age-related differences or because they likely had fewer comorbidities and therefore fewer medications.

The second finding from Matthews et al¹³ that warranted further investigation was a higher erythema rate compared to the older adult study from the United Kingdom.¹⁷ We hypothesized that potentially greater use of photosensitizing medications in the United States could explain the higher erythema rates. Although medication-induced photosensitivity is less likely with NB-UVB phototherapy than with UVA, certain medications can cause UVB photosensitivity, including thiazides, quinidine, calcium channel antagonists, phenothiazines, and nonsteroidal anti-inflammatory drugs.^8,19,20 Therefore, photosensitizing medication use either at baseline or during a course of NB-UVB phototherapy could increase the risk for erythema. Age-related skin changes also have been considered as a potential cause for erythema. One study found that the skin of older patients was more sensitive than younger patients, resulting in a lower minimal erythema dose (MED)¹⁴—the lowest UV dose that results in erythema.²¹ Others, however, found similar MEDs across age groups, but older adults experienced more intense erythema in the late phase of NB-UVB treatment.^22,23 Such conflicting findings indicate that questions remain regarding the risk for erythema in older patients and if photosensitizing medications are responsible for an increased risk.

This retrospective study aimed to determine if NB-UVB phototherapy is equally effective in both older and younger adults treated with the same protocol; to examine the association between the use of photosensitizing medications and clearance rates in both older and younger adults; and to examine the association between the use of photosensitizing medications and erythema rates in older vs younger adults.

Methods

Study Design and Patients—This retrospective cohort study used billing records to identify patients who received NB-UVB phototherapy at 3 different clinical sites within a large US health care system in Washington (Group Health Cooperative, now Kaiser Permanente Washington), serving more than 600,000 patients between January 1, 2012, and December 31, 2016. The institutional review board of Kaiser Permanente Washington Health Research Institute approved this study (IRB 1498087-4). Younger adults were classified as those 64 years or younger and older adults as those 65 years and older at the start of their phototherapy regimen. A power analysis determined that the optimal sample size for this study was 250 patients.

Individuals were excluded if they had fewer than 6 phototherapy treatments; a diagnosis of vitiligo, photosensitivity dermatitis, morphea, or pityriasis rubra pilaris; and/or treatment of the hands or feet only.

Phototherapy Protocol—Using a 48-lamp NB-UVB unit, trained phototherapy nurses provided all treatments following standardized treatment protocols¹³ based on previously published phototherapy guidelines.²⁴ Nurses determined each patient’s disease clearance level using a 3-point clearance scale (high, medium, low).¹³ Each patient’s starting dose was determined based on the estimated MED for their skin phototype. If the patient was using photosensitizing medications, the protocol indicated a need for a decreased starting dose—down 25% to 50%—depending on the presumed level of photosensitivity. All clinical sites used the same protocol, but decisions about adjustments within this range were made by individual registered nurses and dermatologists, which could lead to variability across sites. Protocols also directed nurses to query patients about specific treatment responses, including erythema, tenderness, or itching; how their condition was responding; use of photosensitizing medications; missed treatments; and placement of shielding. Doses were adjusted accordingly.

Statistical Analysis—Data were analyzed using Stata statistical software (StataCorp LLC). Univariate analyses were used to examine the data and identify outliers, bad values, and missing data, as well as to calculate descriptive statistics. Pearson χ² and Fisher exact statistics were used to calculate differences in categorical variables. Linear multivariate regression models and logistic multivariate models were used to examine statistical relationships between variables. Statistical significance was defined as P≤.05.

Results

Patient Characteristics—Medical records were reviewed for 172 patients who received phototherapy between 2012 and 2016. Patients ranged in age from 23 to 91 years, with 102 patients 64 years and younger and 70 patients 65 years and older. Tables 1 and 2 outline the patient characteristics and conditions treated.

Phototherapy Effectiveness—Narrowband UVB phototherapy was found to be equally effective in older vs younger adults, with 82.9% of older adults (n=58) achieving a high level of clearance vs 80.4% (n=82) of younger adults, and 5.7% (n=4) of older adults achieved a medium level of clearance vs 10% (n=10) of younger adults (Table 3). Although older adults had slightly faster clearance rates on average (34.6 vs 37.2 treatments), these differences were not significant.

Photosensitizing Medications, Clearance Levels, and Clearance Rates—There was no significant association between clearance levels and number of photosensitizing medications in either younger (Figure 1) or older (Figure 2) adults. There was a wide range of clearance rates in both groups (Table 3), but no relationship was identified between clearance rates and photosensitizing medications or age (Figure 3). Clinic C had higher overall clearance rates for both age groups compared to the other clinics (Figure 4), but the clearance levels were still equivalent. No consistent pattern emerged indicating that age was a factor for the slower clearance at this site, and no relationship was identified between taking photosensitizing medications and clearance levels (Fisher exact test, P=.467) or clearance rates (t[149]=0.75; P=.45).

Frequency of Treatments and Clearance Rates—Older adults more consistently completed the recommended frequency of treatments—3 times weekly—compared to younger adults (74.3% vs 58.5%). However, all patients who completed 3 treatments per week required a similar number of treatments to clear (older adults, mean [SD]: 35.7 [21.6]; younger adults, mean [SD]: 34.7 [19.0]; P=.85). Among patients completing 2 or fewer treatments per week, older adults required a mean (SD) of only 31 (9.0) treatments to clear vs 41.5 (21.3) treatments to clear for younger adults, but the difference was not statistically significant (P=.08). However, even those with suboptimal frequency ultimately achieved similar clearance levels.

Photosensitizing Medications and Erythema Rates—Many patients in both age groups took medications that listed photosensitivity as a potential side effect (77.1% of older adults and 60.8% of younger adults). Of them, most patients took only 1 or 2 photosensitizing medications. However, significantly more older patients took 3 or more photosensitizing medications (28.6% vs 12.7%; P=.01)(Table 3). Asymptomatic (grade 1) erythema was unrelated to medication use and quite common in all adults (48.6% of older adults and 60.8% of younger adults). Most patients had only a few episodes of grade 1 erythema (mean [SD], 1.2 [2.9] in older adults and 1.6 [2.2] in younger adults). More older adults had grade 2 erythema (28.6%) compared to younger adults (17.6%). Patients using 3 or more photosensitizing medications were twice as likely to experience grade 2 erythema. Grades 3 and 4 erythema were extremely rare; none of the patients stopped phototherapy because they experienced erythema.

Overall, phototherapy nurses adjusted the starting dose according to the phototype-based protocol an average of 69% of the time for patients on medications with photosensitivity listed as a potential side effect. However, the frequency depended significantly on the clinic (clinic A, 24%; clinic B, 92%; clinic C, 87%)(P≤.001). Nurses across all clinics consistently decreased the treatment dose when patients reported starting new photosensitizing medications. Patients with adjusted starting doses had slightly but not significantly higher clearance rates compared to those without (mean, 37.8 vs 35.5; t(104)=0.58; P=.56).

Comment

Comparisons to Prior Studies—This study confirmed that phototherapy is equally effective for older and younger adults, with approximately 90% reaching medium to high clearance levels with approximately 35 treatments in both groups. Prior studies of all age groups found that patients typically cleared with an average of 20 to 28 treatments.^7,8,14-16 In contrast, the findings in older adults from this study were similar to the older adult study from the United Kingdom that reported a 91% clear/near clear rate with an average of 30 treatments.¹⁷ The clearance level also was similar to the older adult study in Turkey¹⁸ that reported 73.7% (70/95) of patients with psoriasis achieved a minimum psoriasis area severity index of 75, indicating 75% improvement from baseline.

Impact of Photosensitizing Medications on Clearance—Photosensitizing medications and treatment frequency were 2 factors that might explain the slower clearance rates in younger adults. In this study, both groups of patients used similar numbers of photosensitizing medications, but more older adults were taking 3 or more medications (Table 3). We found no statistically significant relationship between taking photosensitizing medications and either the clearance rates or the level of clearance achieved in either age group.

Impact of Treatment Frequency—Weekly treatment frequency also was examined. One prior study demonstrated that treatments 3 times weekly led to a faster clearance time and higher clearance levels compared with twice-weekly treatment.⁷ When patients completed treatments twice weekly, it took an average of 1.5 times more days to clear, which impacted cost and clinical resource availability. The patients ranged in age from 17 to 80 years, but outcomes in older patients were not described separately.⁷ Interestingly, our study seemed to find a difference between age groups when the impact of treatment frequency was examined. Older adults completed nearly 4 fewer mean treatments to clear when treating less often, with more than 80% achieving high levels of clearance, whereas the younger adults required almost 7 more treatments to clear when they came in less frequently, with approximately 80% achieving a high level of clearance. As a result, our study found that in both age groups, slowing the treatment frequency extended the treatment time to clearance—more for the younger adults than the older adults—but did not significantly change the percentage of individuals reaching full clearance in either group.

Erythema Rates—There was no association between photosensitizing medications and erythema rates except when patients were taking at least 3 medications. Most medications that listed photosensitivity as a possible side effect did not specify their relevant range of UV radiation; therefore, all such medications were examined during this analysis. Prior research has shown UVB range photosensitizing medications include thiazides, quinidine, calcium channel antagonists, phenothiazines, and nonsteroidal anti-inflammatory drugs.¹⁹ A sensitivity analysis that focused only on these medications found no association between them and any particular grade of erythema. However, patients taking 3 or more of any medications listing photosensitivity as a side effect had an increased risk for grade 2 erythema.

Erythema rates in this study were consistent with a 2013 systematic review that reported 57% of patients with asymptomatic grade 1 erythema.²⁵ In the 2 other comparative older adult studies, erythema rates varied widely: 35% in a study from Turkey¹⁸compared to only1.89% in a study from the United Kingdom.¹⁷

The starting dose for NB-UVB may drive erythema rates. The current study’s protocols were based on an estimated MED that is subjectively determined by the dermatology provider’s assessment of the patient’s skin sensitivity via examination and questions to the patient about their response to environmental sun exposure (ie, burning and tanning)²⁶ and is frequently used to determine the starting dose and subsequent dose escalation. Certain medications have been found to increase photosensitivity and erythema,²⁰ which can change an individual’s MED. If photosensitizing medications are started prior to or during a course of NB-UVB without a pretreatment MED, they might increase the risk for erythema. This study did not identify specific erythema-inducing medications but did find that taking 3 or more photosensitizing medications was associated with increased episodes of grade 2 erythema. Similarly, Harrop et al⁸ found that patients who were taking photosensitizing medications were more likely to have grade 2 or higher erythema, despite baseline MED testing, which is an established safety mechanism to reduce the risk and severity of erythema.^14,20,27 The authors of a recent study of older adults in Taiwan specifically recommended MED testing due to the unpredictable influence of polypharmacy on MED calculations in this population.²⁸ Therefore, this study’s use of an estimated MED in older adults may have influenced the starting dose as well as the incidence and severity of erythemic events. Age-related skin changes likely are ruled out as a consideration for mild erythema by the similarity of grade 1 erythema rates in both older and younger adults. Other studies have identified differences between the age groups, where older patients experienced more intense erythema in the late phase of UVB treatments.^22,23 This phenomenon could increase the risk for a grade 2 erythema, which may correspond with this study’s findings.

Other potential causes of erythema were ruled out during our study, including erythema related to missed treatments and shielding mishaps. Other factors, however, may impact the level of sensitivity each patient has to phototherapy, including genetics, epigenetics, and cumulative sun damage. With NB-UVB, near-erythemogenic doses are optimal to achieve effective treatments but require a delicate balance to achieve, which may be more problematic for older adults, especially those taking several medications.

Study Limitations—Our study design made it difficult to draw conclusions about rarer dermatologic conditions. Some patients received treatments over years that were not included in the study period. Finally, power calculations suggested that our actual sample size was too small, with approximately one-third of the required sample missing.

Practical Implications—The goals of phototherapy are to achieve a high level of disease clearance with the fewest number of treatments possible and minimal side effects. Skin phototype–driven standardized doses based on estimated MED may be conservatively low to minimize the risk of side effects (eg, erythema), which could slow the treatment progression. Thus, basing the starting dose on individual MED assessments may improve clearance rates. This study also confirmed that phototherapy is safe with minimal erythema in adults of all ages. The erythema episodes that patients experienced were few and mild, but because of greater rates of grade 2 erythema in patients on 3 or more photosensitizing medications, consideration of MED testing in both age groups might optimize doses at baseline and prompt caution for subsequent dose titration in this subset of patients.

The extra staff training and patient monitoring required for MED testing likely is to add value and preserve resources if faster clearance rates could be achieved and may warrant further investigation. Phototherapy centers require standardized treatment protocols, diligent well-trained staff, and program monitoring to ensure consistent care to all patients. This study highlighted the ongoing opportunity for health care organizations to conduct evidence-based practice inquiries to continually optimize care for their patients.

Even with recent pharmacologic treatment advances, narrowband UVB (NB-UVB) phototherapy remains a versatile, safe, and efficacious adjunctive or exclusive treatment for multiple dermatologic conditions, including psoriasis and atopic dermatitis. ^1-9 Some providers choose NB-UVB phototherapy as a first-line treatment for older adult patients who frequently use multiple treatment modalities for more than 1 health condition. Older adults with atopic dermatitis and psoriasis are at higher risk for comorbidities such as autoimmune disorders, diabetes mellitus, dyslipidemia, sleep disorders, neuropsychiatric disorders, and cardiovascular disease that can complicate treatment compared with their peers without these dermatologic diagnoses. ^10-12 Polypharmacy (ie, the use of 5 or more daily medications), frequently associated with these conditions, contributes to prescribers pursuing NB-UVB phototherapy as a nonpharmacologic treatment, but some providers wonder if it is as effective and safe for their older patients compared with younger patients.

In a prior study, Matthews et al¹³ reported that 96% (50/52) of patients older than 65 years achieved medium to high levels of clearance with NB-UVB phototherapy. Nonetheless, 2 other findings in this study related to the number of treatments required to achieve clearance (ie, clearance rates) and erythema rates prompted further investigation. The first finding was higher-than-expected clearance rates. Older adults had a clearance rate with a mean of 33 treatments compared to prior studies featuring mean clearance rates of 20 to 28 treatments.^7,8,14-16 This finding resembled a study in the United Kingdom¹⁷ with a median clearance rate in older adults of 30 treatments. In contrast, the median clearance rate from a study in Turkey¹⁸ was 42 treatments in older adults. We hypothesized that more photosensitizing medications used in older vs younger adults prompted more dose adjustments with NB-UVB phototherapy to avoid burning (ie, erythema) at baseline and throughout the treatment course. These dose adjustments may have increased the overall clearance rates. If true, we predicted that younger adults treated with the same protocol would have cleared more quickly, either because of age-related differences or because they likely had fewer comorbidities and therefore fewer medications.

The second finding from Matthews et al¹³ that warranted further investigation was a higher erythema rate compared to the older adult study from the United Kingdom.¹⁷ We hypothesized that potentially greater use of photosensitizing medications in the United States could explain the higher erythema rates. Although medication-induced photosensitivity is less likely with NB-UVB phototherapy than with UVA, certain medications can cause UVB photosensitivity, including thiazides, quinidine, calcium channel antagonists, phenothiazines, and nonsteroidal anti-inflammatory drugs.^8,19,20 Therefore, photosensitizing medication use either at baseline or during a course of NB-UVB phototherapy could increase the risk for erythema. Age-related skin changes also have been considered as a potential cause for erythema. One study found that the skin of older patients was more sensitive than younger patients, resulting in a lower minimal erythema dose (MED)¹⁴—the lowest UV dose that results in erythema.²¹ Others, however, found similar MEDs across age groups, but older adults experienced more intense erythema in the late phase of NB-UVB treatment.^22,23 Such conflicting findings indicate that questions remain regarding the risk for erythema in older patients and if photosensitizing medications are responsible for an increased risk.

This retrospective study aimed to determine if NB-UVB phototherapy is equally effective in both older and younger adults treated with the same protocol; to examine the association between the use of photosensitizing medications and clearance rates in both older and younger adults; and to examine the association between the use of photosensitizing medications and erythema rates in older vs younger adults.

Methods

Study Design and Patients—This retrospective cohort study used billing records to identify patients who received NB-UVB phototherapy at 3 different clinical sites within a large US health care system in Washington (Group Health Cooperative, now Kaiser Permanente Washington), serving more than 600,000 patients between January 1, 2012, and December 31, 2016. The institutional review board of Kaiser Permanente Washington Health Research Institute approved this study (IRB 1498087-4). Younger adults were classified as those 64 years or younger and older adults as those 65 years and older at the start of their phototherapy regimen. A power analysis determined that the optimal sample size for this study was 250 patients.

Individuals were excluded if they had fewer than 6 phototherapy treatments; a diagnosis of vitiligo, photosensitivity dermatitis, morphea, or pityriasis rubra pilaris; and/or treatment of the hands or feet only.

Phototherapy Protocol—Using a 48-lamp NB-UVB unit, trained phototherapy nurses provided all treatments following standardized treatment protocols¹³ based on previously published phototherapy guidelines.²⁴ Nurses determined each patient’s disease clearance level using a 3-point clearance scale (high, medium, low).¹³ Each patient’s starting dose was determined based on the estimated MED for their skin phototype. If the patient was using photosensitizing medications, the protocol indicated a need for a decreased starting dose—down 25% to 50%—depending on the presumed level of photosensitivity. All clinical sites used the same protocol, but decisions about adjustments within this range were made by individual registered nurses and dermatologists, which could lead to variability across sites. Protocols also directed nurses to query patients about specific treatment responses, including erythema, tenderness, or itching; how their condition was responding; use of photosensitizing medications; missed treatments; and placement of shielding. Doses were adjusted accordingly.

Statistical Analysis—Data were analyzed using Stata statistical software (StataCorp LLC). Univariate analyses were used to examine the data and identify outliers, bad values, and missing data, as well as to calculate descriptive statistics. Pearson χ² and Fisher exact statistics were used to calculate differences in categorical variables. Linear multivariate regression models and logistic multivariate models were used to examine statistical relationships between variables. Statistical significance was defined as P≤.05.

Results

Patient Characteristics—Medical records were reviewed for 172 patients who received phototherapy between 2012 and 2016. Patients ranged in age from 23 to 91 years, with 102 patients 64 years and younger and 70 patients 65 years and older. Tables 1 and 2 outline the patient characteristics and conditions treated.

Phototherapy Effectiveness—Narrowband UVB phototherapy was found to be equally effective in older vs younger adults, with 82.9% of older adults (n=58) achieving a high level of clearance vs 80.4% (n=82) of younger adults, and 5.7% (n=4) of older adults achieved a medium level of clearance vs 10% (n=10) of younger adults (Table 3). Although older adults had slightly faster clearance rates on average (34.6 vs 37.2 treatments), these differences were not significant.

Photosensitizing Medications, Clearance Levels, and Clearance Rates—There was no significant association between clearance levels and number of photosensitizing medications in either younger (Figure 1) or older (Figure 2) adults. There was a wide range of clearance rates in both groups (Table 3), but no relationship was identified between clearance rates and photosensitizing medications or age (Figure 3). Clinic C had higher overall clearance rates for both age groups compared to the other clinics (Figure 4), but the clearance levels were still equivalent. No consistent pattern emerged indicating that age was a factor for the slower clearance at this site, and no relationship was identified between taking photosensitizing medications and clearance levels (Fisher exact test, P=.467) or clearance rates (t[149]=0.75; P=.45).

Frequency of Treatments and Clearance Rates—Older adults more consistently completed the recommended frequency of treatments—3 times weekly—compared to younger adults (74.3% vs 58.5%). However, all patients who completed 3 treatments per week required a similar number of treatments to clear (older adults, mean [SD]: 35.7 [21.6]; younger adults, mean [SD]: 34.7 [19.0]; P=.85). Among patients completing 2 or fewer treatments per week, older adults required a mean (SD) of only 31 (9.0) treatments to clear vs 41.5 (21.3) treatments to clear for younger adults, but the difference was not statistically significant (P=.08). However, even those with suboptimal frequency ultimately achieved similar clearance levels.

Photosensitizing Medications and Erythema Rates—Many patients in both age groups took medications that listed photosensitivity as a potential side effect (77.1% of older adults and 60.8% of younger adults). Of them, most patients took only 1 or 2 photosensitizing medications. However, significantly more older patients took 3 or more photosensitizing medications (28.6% vs 12.7%; P=.01)(Table 3). Asymptomatic (grade 1) erythema was unrelated to medication use and quite common in all adults (48.6% of older adults and 60.8% of younger adults). Most patients had only a few episodes of grade 1 erythema (mean [SD], 1.2 [2.9] in older adults and 1.6 [2.2] in younger adults). More older adults had grade 2 erythema (28.6%) compared to younger adults (17.6%). Patients using 3 or more photosensitizing medications were twice as likely to experience grade 2 erythema. Grades 3 and 4 erythema were extremely rare; none of the patients stopped phototherapy because they experienced erythema.

Overall, phototherapy nurses adjusted the starting dose according to the phototype-based protocol an average of 69% of the time for patients on medications with photosensitivity listed as a potential side effect. However, the frequency depended significantly on the clinic (clinic A, 24%; clinic B, 92%; clinic C, 87%)(P≤.001). Nurses across all clinics consistently decreased the treatment dose when patients reported starting new photosensitizing medications. Patients with adjusted starting doses had slightly but not significantly higher clearance rates compared to those without (mean, 37.8 vs 35.5; t(104)=0.58; P=.56).

Comment

Comparisons to Prior Studies—This study confirmed that phototherapy is equally effective for older and younger adults, with approximately 90% reaching medium to high clearance levels with approximately 35 treatments in both groups. Prior studies of all age groups found that patients typically cleared with an average of 20 to 28 treatments.^7,8,14-16 In contrast, the findings in older adults from this study were similar to the older adult study from the United Kingdom that reported a 91% clear/near clear rate with an average of 30 treatments.¹⁷ The clearance level also was similar to the older adult study in Turkey¹⁸ that reported 73.7% (70/95) of patients with psoriasis achieved a minimum psoriasis area severity index of 75, indicating 75% improvement from baseline.

Impact of Photosensitizing Medications on Clearance—Photosensitizing medications and treatment frequency were 2 factors that might explain the slower clearance rates in younger adults. In this study, both groups of patients used similar numbers of photosensitizing medications, but more older adults were taking 3 or more medications (Table 3). We found no statistically significant relationship between taking photosensitizing medications and either the clearance rates or the level of clearance achieved in either age group.

Impact of Treatment Frequency—Weekly treatment frequency also was examined. One prior study demonstrated that treatments 3 times weekly led to a faster clearance time and higher clearance levels compared with twice-weekly treatment.⁷ When patients completed treatments twice weekly, it took an average of 1.5 times more days to clear, which impacted cost and clinical resource availability. The patients ranged in age from 17 to 80 years, but outcomes in older patients were not described separately.⁷ Interestingly, our study seemed to find a difference between age groups when the impact of treatment frequency was examined. Older adults completed nearly 4 fewer mean treatments to clear when treating less often, with more than 80% achieving high levels of clearance, whereas the younger adults required almost 7 more treatments to clear when they came in less frequently, with approximately 80% achieving a high level of clearance. As a result, our study found that in both age groups, slowing the treatment frequency extended the treatment time to clearance—more for the younger adults than the older adults—but did not significantly change the percentage of individuals reaching full clearance in either group.

Erythema Rates—There was no association between photosensitizing medications and erythema rates except when patients were taking at least 3 medications. Most medications that listed photosensitivity as a possible side effect did not specify their relevant range of UV radiation; therefore, all such medications were examined during this analysis. Prior research has shown UVB range photosensitizing medications include thiazides, quinidine, calcium channel antagonists, phenothiazines, and nonsteroidal anti-inflammatory drugs.¹⁹ A sensitivity analysis that focused only on these medications found no association between them and any particular grade of erythema. However, patients taking 3 or more of any medications listing photosensitivity as a side effect had an increased risk for grade 2 erythema.

Erythema rates in this study were consistent with a 2013 systematic review that reported 57% of patients with asymptomatic grade 1 erythema.²⁵ In the 2 other comparative older adult studies, erythema rates varied widely: 35% in a study from Turkey¹⁸compared to only1.89% in a study from the United Kingdom.¹⁷

The starting dose for NB-UVB may drive erythema rates. The current study’s protocols were based on an estimated MED that is subjectively determined by the dermatology provider’s assessment of the patient’s skin sensitivity via examination and questions to the patient about their response to environmental sun exposure (ie, burning and tanning)²⁶ and is frequently used to determine the starting dose and subsequent dose escalation. Certain medications have been found to increase photosensitivity and erythema,²⁰ which can change an individual’s MED. If photosensitizing medications are started prior to or during a course of NB-UVB without a pretreatment MED, they might increase the risk for erythema. This study did not identify specific erythema-inducing medications but did find that taking 3 or more photosensitizing medications was associated with increased episodes of grade 2 erythema. Similarly, Harrop et al⁸ found that patients who were taking photosensitizing medications were more likely to have grade 2 or higher erythema, despite baseline MED testing, which is an established safety mechanism to reduce the risk and severity of erythema.^14,20,27 The authors of a recent study of older adults in Taiwan specifically recommended MED testing due to the unpredictable influence of polypharmacy on MED calculations in this population.²⁸ Therefore, this study’s use of an estimated MED in older adults may have influenced the starting dose as well as the incidence and severity of erythemic events. Age-related skin changes likely are ruled out as a consideration for mild erythema by the similarity of grade 1 erythema rates in both older and younger adults. Other studies have identified differences between the age groups, where older patients experienced more intense erythema in the late phase of UVB treatments.^22,23 This phenomenon could increase the risk for a grade 2 erythema, which may correspond with this study’s findings.

Other potential causes of erythema were ruled out during our study, including erythema related to missed treatments and shielding mishaps. Other factors, however, may impact the level of sensitivity each patient has to phototherapy, including genetics, epigenetics, and cumulative sun damage. With NB-UVB, near-erythemogenic doses are optimal to achieve effective treatments but require a delicate balance to achieve, which may be more problematic for older adults, especially those taking several medications.

Study Limitations—Our study design made it difficult to draw conclusions about rarer dermatologic conditions. Some patients received treatments over years that were not included in the study period. Finally, power calculations suggested that our actual sample size was too small, with approximately one-third of the required sample missing.

Practical Implications—The goals of phototherapy are to achieve a high level of disease clearance with the fewest number of treatments possible and minimal side effects. Skin phototype–driven standardized doses based on estimated MED may be conservatively low to minimize the risk of side effects (eg, erythema), which could slow the treatment progression. Thus, basing the starting dose on individual MED assessments may improve clearance rates. This study also confirmed that phototherapy is safe with minimal erythema in adults of all ages. The erythema episodes that patients experienced were few and mild, but because of greater rates of grade 2 erythema in patients on 3 or more photosensitizing medications, consideration of MED testing in both age groups might optimize doses at baseline and prompt caution for subsequent dose titration in this subset of patients.

The extra staff training and patient monitoring required for MED testing likely is to add value and preserve resources if faster clearance rates could be achieved and may warrant further investigation. Phototherapy centers require standardized treatment protocols, diligent well-trained staff, and program monitoring to ensure consistent care to all patients. This study highlighted the ongoing opportunity for health care organizations to conduct evidence-based practice inquiries to continually optimize care for their patients.

Even with recent pharmacologic treatment advances, narrowband UVB (NB-UVB) phototherapy remains a versatile, safe, and efficacious adjunctive or exclusive treatment for multiple dermatologic conditions, including psoriasis and atopic dermatitis. ^1-9 Some providers choose NB-UVB phototherapy as a first-line treatment for older adult patients who frequently use multiple treatment modalities for more than 1 health condition. Older adults with atopic dermatitis and psoriasis are at higher risk for comorbidities such as autoimmune disorders, diabetes mellitus, dyslipidemia, sleep disorders, neuropsychiatric disorders, and cardiovascular disease that can complicate treatment compared with their peers without these dermatologic diagnoses. ^10-12 Polypharmacy (ie, the use of 5 or more daily medications), frequently associated with these conditions, contributes to prescribers pursuing NB-UVB phototherapy as a nonpharmacologic treatment, but some providers wonder if it is as effective and safe for their older patients compared with younger patients.

In a prior study, Matthews et al¹³ reported that 96% (50/52) of patients older than 65 years achieved medium to high levels of clearance with NB-UVB phototherapy. Nonetheless, 2 other findings in this study related to the number of treatments required to achieve clearance (ie, clearance rates) and erythema rates prompted further investigation. The first finding was higher-than-expected clearance rates. Older adults had a clearance rate with a mean of 33 treatments compared to prior studies featuring mean clearance rates of 20 to 28 treatments.^7,8,14-16 This finding resembled a study in the United Kingdom¹⁷ with a median clearance rate in older adults of 30 treatments. In contrast, the median clearance rate from a study in Turkey¹⁸ was 42 treatments in older adults. We hypothesized that more photosensitizing medications used in older vs younger adults prompted more dose adjustments with NB-UVB phototherapy to avoid burning (ie, erythema) at baseline and throughout the treatment course. These dose adjustments may have increased the overall clearance rates. If true, we predicted that younger adults treated with the same protocol would have cleared more quickly, either because of age-related differences or because they likely had fewer comorbidities and therefore fewer medications.

The second finding from Matthews et al¹³ that warranted further investigation was a higher erythema rate compared to the older adult study from the United Kingdom.¹⁷ We hypothesized that potentially greater use of photosensitizing medications in the United States could explain the higher erythema rates. Although medication-induced photosensitivity is less likely with NB-UVB phototherapy than with UVA, certain medications can cause UVB photosensitivity, including thiazides, quinidine, calcium channel antagonists, phenothiazines, and nonsteroidal anti-inflammatory drugs.^8,19,20 Therefore, photosensitizing medication use either at baseline or during a course of NB-UVB phototherapy could increase the risk for erythema. Age-related skin changes also have been considered as a potential cause for erythema. One study found that the skin of older patients was more sensitive than younger patients, resulting in a lower minimal erythema dose (MED)¹⁴—the lowest UV dose that results in erythema.²¹ Others, however, found similar MEDs across age groups, but older adults experienced more intense erythema in the late phase of NB-UVB treatment.^22,23 Such conflicting findings indicate that questions remain regarding the risk for erythema in older patients and if photosensitizing medications are responsible for an increased risk.

This retrospective study aimed to determine if NB-UVB phototherapy is equally effective in both older and younger adults treated with the same protocol; to examine the association between the use of photosensitizing medications and clearance rates in both older and younger adults; and to examine the association between the use of photosensitizing medications and erythema rates in older vs younger adults.

Methods

Study Design and Patients—This retrospective cohort study used billing records to identify patients who received NB-UVB phototherapy at 3 different clinical sites within a large US health care system in Washington (Group Health Cooperative, now Kaiser Permanente Washington), serving more than 600,000 patients between January 1, 2012, and December 31, 2016. The institutional review board of Kaiser Permanente Washington Health Research Institute approved this study (IRB 1498087-4). Younger adults were classified as those 64 years or younger and older adults as those 65 years and older at the start of their phototherapy regimen. A power analysis determined that the optimal sample size for this study was 250 patients.

Individuals were excluded if they had fewer than 6 phototherapy treatments; a diagnosis of vitiligo, photosensitivity dermatitis, morphea, or pityriasis rubra pilaris; and/or treatment of the hands or feet only.

Phototherapy Protocol—Using a 48-lamp NB-UVB unit, trained phototherapy nurses provided all treatments following standardized treatment protocols¹³ based on previously published phototherapy guidelines.²⁴ Nurses determined each patient’s disease clearance level using a 3-point clearance scale (high, medium, low).¹³ Each patient’s starting dose was determined based on the estimated MED for their skin phototype. If the patient was using photosensitizing medications, the protocol indicated a need for a decreased starting dose—down 25% to 50%—depending on the presumed level of photosensitivity. All clinical sites used the same protocol, but decisions about adjustments within this range were made by individual registered nurses and dermatologists, which could lead to variability across sites. Protocols also directed nurses to query patients about specific treatment responses, including erythema, tenderness, or itching; how their condition was responding; use of photosensitizing medications; missed treatments; and placement of shielding. Doses were adjusted accordingly.

Statistical Analysis—Data were analyzed using Stata statistical software (StataCorp LLC). Univariate analyses were used to examine the data and identify outliers, bad values, and missing data, as well as to calculate descriptive statistics. Pearson χ² and Fisher exact statistics were used to calculate differences in categorical variables. Linear multivariate regression models and logistic multivariate models were used to examine statistical relationships between variables. Statistical significance was defined as P≤.05.

Results

Patient Characteristics—Medical records were reviewed for 172 patients who received phototherapy between 2012 and 2016. Patients ranged in age from 23 to 91 years, with 102 patients 64 years and younger and 70 patients 65 years and older. Tables 1 and 2 outline the patient characteristics and conditions treated.

Phototherapy Effectiveness—Narrowband UVB phototherapy was found to be equally effective in older vs younger adults, with 82.9% of older adults (n=58) achieving a high level of clearance vs 80.4% (n=82) of younger adults, and 5.7% (n=4) of older adults achieved a medium level of clearance vs 10% (n=10) of younger adults (Table 3). Although older adults had slightly faster clearance rates on average (34.6 vs 37.2 treatments), these differences were not significant.

Photosensitizing Medications, Clearance Levels, and Clearance Rates—There was no significant association between clearance levels and number of photosensitizing medications in either younger (Figure 1) or older (Figure 2) adults. There was a wide range of clearance rates in both groups (Table 3), but no relationship was identified between clearance rates and photosensitizing medications or age (Figure 3). Clinic C had higher overall clearance rates for both age groups compared to the other clinics (Figure 4), but the clearance levels were still equivalent. No consistent pattern emerged indicating that age was a factor for the slower clearance at this site, and no relationship was identified between taking photosensitizing medications and clearance levels (Fisher exact test, P=.467) or clearance rates (t[149]=0.75; P=.45).

Frequency of Treatments and Clearance Rates—Older adults more consistently completed the recommended frequency of treatments—3 times weekly—compared to younger adults (74.3% vs 58.5%). However, all patients who completed 3 treatments per week required a similar number of treatments to clear (older adults, mean [SD]: 35.7 [21.6]; younger adults, mean [SD]: 34.7 [19.0]; P=.85). Among patients completing 2 or fewer treatments per week, older adults required a mean (SD) of only 31 (9.0) treatments to clear vs 41.5 (21.3) treatments to clear for younger adults, but the difference was not statistically significant (P=.08). However, even those with suboptimal frequency ultimately achieved similar clearance levels.

Photosensitizing Medications and Erythema Rates—Many patients in both age groups took medications that listed photosensitivity as a potential side effect (77.1% of older adults and 60.8% of younger adults). Of them, most patients took only 1 or 2 photosensitizing medications. However, significantly more older patients took 3 or more photosensitizing medications (28.6% vs 12.7%; P=.01)(Table 3). Asymptomatic (grade 1) erythema was unrelated to medication use and quite common in all adults (48.6% of older adults and 60.8% of younger adults). Most patients had only a few episodes of grade 1 erythema (mean [SD], 1.2 [2.9] in older adults and 1.6 [2.2] in younger adults). More older adults had grade 2 erythema (28.6%) compared to younger adults (17.6%). Patients using 3 or more photosensitizing medications were twice as likely to experience grade 2 erythema. Grades 3 and 4 erythema were extremely rare; none of the patients stopped phototherapy because they experienced erythema.

Overall, phototherapy nurses adjusted the starting dose according to the phototype-based protocol an average of 69% of the time for patients on medications with photosensitivity listed as a potential side effect. However, the frequency depended significantly on the clinic (clinic A, 24%; clinic B, 92%; clinic C, 87%)(P≤.001). Nurses across all clinics consistently decreased the treatment dose when patients reported starting new photosensitizing medications. Patients with adjusted starting doses had slightly but not significantly higher clearance rates compared to those without (mean, 37.8 vs 35.5; t(104)=0.58; P=.56).

Comment

Comparisons to Prior Studies—This study confirmed that phototherapy is equally effective for older and younger adults, with approximately 90% reaching medium to high clearance levels with approximately 35 treatments in both groups. Prior studies of all age groups found that patients typically cleared with an average of 20 to 28 treatments.^7,8,14-16 In contrast, the findings in older adults from this study were similar to the older adult study from the United Kingdom that reported a 91% clear/near clear rate with an average of 30 treatments.¹⁷ The clearance level also was similar to the older adult study in Turkey¹⁸ that reported 73.7% (70/95) of patients with psoriasis achieved a minimum psoriasis area severity index of 75, indicating 75% improvement from baseline.

Impact of Photosensitizing Medications on Clearance—Photosensitizing medications and treatment frequency were 2 factors that might explain the slower clearance rates in younger adults. In this study, both groups of patients used similar numbers of photosensitizing medications, but more older adults were taking 3 or more medications (Table 3). We found no statistically significant relationship between taking photosensitizing medications and either the clearance rates or the level of clearance achieved in either age group.

Impact of Treatment Frequency—Weekly treatment frequency also was examined. One prior study demonstrated that treatments 3 times weekly led to a faster clearance time and higher clearance levels compared with twice-weekly treatment.⁷ When patients completed treatments twice weekly, it took an average of 1.5 times more days to clear, which impacted cost and clinical resource availability. The patients ranged in age from 17 to 80 years, but outcomes in older patients were not described separately.⁷ Interestingly, our study seemed to find a difference between age groups when the impact of treatment frequency was examined. Older adults completed nearly 4 fewer mean treatments to clear when treating less often, with more than 80% achieving high levels of clearance, whereas the younger adults required almost 7 more treatments to clear when they came in less frequently, with approximately 80% achieving a high level of clearance. As a result, our study found that in both age groups, slowing the treatment frequency extended the treatment time to clearance—more for the younger adults than the older adults—but did not significantly change the percentage of individuals reaching full clearance in either group.

Erythema Rates—There was no association between photosensitizing medications and erythema rates except when patients were taking at least 3 medications. Most medications that listed photosensitivity as a possible side effect did not specify their relevant range of UV radiation; therefore, all such medications were examined during this analysis. Prior research has shown UVB range photosensitizing medications include thiazides, quinidine, calcium channel antagonists, phenothiazines, and nonsteroidal anti-inflammatory drugs.¹⁹ A sensitivity analysis that focused only on these medications found no association between them and any particular grade of erythema. However, patients taking 3 or more of any medications listing photosensitivity as a side effect had an increased risk for grade 2 erythema.

Erythema rates in this study were consistent with a 2013 systematic review that reported 57% of patients with asymptomatic grade 1 erythema.²⁵ In the 2 other comparative older adult studies, erythema rates varied widely: 35% in a study from Turkey¹⁸compared to only1.89% in a study from the United Kingdom.¹⁷

The starting dose for NB-UVB may drive erythema rates. The current study’s protocols were based on an estimated MED that is subjectively determined by the dermatology provider’s assessment of the patient’s skin sensitivity via examination and questions to the patient about their response to environmental sun exposure (ie, burning and tanning)²⁶ and is frequently used to determine the starting dose and subsequent dose escalation. Certain medications have been found to increase photosensitivity and erythema,²⁰ which can change an individual’s MED. If photosensitizing medications are started prior to or during a course of NB-UVB without a pretreatment MED, they might increase the risk for erythema. This study did not identify specific erythema-inducing medications but did find that taking 3 or more photosensitizing medications was associated with increased episodes of grade 2 erythema. Similarly, Harrop et al⁸ found that patients who were taking photosensitizing medications were more likely to have grade 2 or higher erythema, despite baseline MED testing, which is an established safety mechanism to reduce the risk and severity of erythema.^14,20,27 The authors of a recent study of older adults in Taiwan specifically recommended MED testing due to the unpredictable influence of polypharmacy on MED calculations in this population.²⁸ Therefore, this study’s use of an estimated MED in older adults may have influenced the starting dose as well as the incidence and severity of erythemic events. Age-related skin changes likely are ruled out as a consideration for mild erythema by the similarity of grade 1 erythema rates in both older and younger adults. Other studies have identified differences between the age groups, where older patients experienced more intense erythema in the late phase of UVB treatments.^22,23 This phenomenon could increase the risk for a grade 2 erythema, which may correspond with this study’s findings.

Other potential causes of erythema were ruled out during our study, including erythema related to missed treatments and shielding mishaps. Other factors, however, may impact the level of sensitivity each patient has to phototherapy, including genetics, epigenetics, and cumulative sun damage. With NB-UVB, near-erythemogenic doses are optimal to achieve effective treatments but require a delicate balance to achieve, which may be more problematic for older adults, especially those taking several medications.

Study Limitations—Our study design made it difficult to draw conclusions about rarer dermatologic conditions. Some patients received treatments over years that were not included in the study period. Finally, power calculations suggested that our actual sample size was too small, with approximately one-third of the required sample missing.

Practical Implications—The goals of phototherapy are to achieve a high level of disease clearance with the fewest number of treatments possible and minimal side effects. Skin phototype–driven standardized doses based on estimated MED may be conservatively low to minimize the risk of side effects (eg, erythema), which could slow the treatment progression. Thus, basing the starting dose on individual MED assessments may improve clearance rates. This study also confirmed that phototherapy is safe with minimal erythema in adults of all ages. The erythema episodes that patients experienced were few and mild, but because of greater rates of grade 2 erythema in patients on 3 or more photosensitizing medications, consideration of MED testing in both age groups might optimize doses at baseline and prompt caution for subsequent dose titration in this subset of patients.

The extra staff training and patient monitoring required for MED testing likely is to add value and preserve resources if faster clearance rates could be achieved and may warrant further investigation. Phototherapy centers require standardized treatment protocols, diligent well-trained staff, and program monitoring to ensure consistent care to all patients. This study highlighted the ongoing opportunity for health care organizations to conduct evidence-based practice inquiries to continually optimize care for their patients.

Around half the people who wear face masks may develop acne, facial dermatitis, itch, or pressure injuries, and the risk increases with the length of time the mask is worn, according to a recently published systematic review and meta-analysis.

“This report finds the most statistically significant risk factor for developing a facial dermatosis under a face mask is how long one wears the mask. Specifically, wearing a mask for more than 4 to 6 hours correlated most strongly with the development of a facial skin problem,” Jami L. Miller, MD, associate professor of dermatology, Vanderbilt University Medical Center, Nashville, Tenn., told this news organization. Dr. Miller was not involved in the study.

“The type of mask and the environment were of less significance,” she added.

UerDomwet/PxHere

• The overall prevalence of facial dermatoses was 55%
• Individually, facial dermatitis, itch, acne, and pressure injuries were consistently reported as facial dermatoses, with pooled prevalence rates of 24%, 30%, 31%, and 31%, respectively
• The duration of mask wearing was the most significant risk factor for facial dermatoses (P < .001)
• Respirators, including N95 masks, were not more likely than surgical masks to be linked with facial dermatoses

“Understanding risk factors of mask wearing, including situation, duration, and type of mask, may allow for targeted interventions to mitigate problems,” Dr. Yew told this news organization.

He advised taking a break from mask wearing after 4 to 6 hours to improve outcomes.  

Dr. Yew acknowledged limitations, including that most of the reviewed studies relied on self-reported symptoms.

“Patient factors were not investigated in most studies; therefore, we were not able to ascertain their contributory role in the development of facial dermatoses from mask wearing,” he said. “We were also unable to prove causation between risk factors and outcome.” 

Four dermatologists welcome the findings

Dr. Miller called this an “interesting, and certainly relevant” study, now that mask wearing is common and facial skin problems are fairly common complaints in medical visits.

“As the authors say, irritants or contact allergens with longer exposures can be expected to cause a more severe dermatitis than short contact,” she said. “Longer duration also can cause occlusion of pores and hair follicles, which can be expected to worsen acne and folliculitis.”

“I was surprised that the type of mask did not seem to matter significantly,” she added. “Patients wearing N95 masks may be relieved to know N95s do not cause more skin problems than lighter masks.”

Still, Dr. Miller had several questions, including if the materials and chemical finishes that vary by manufacturer may affect skin conditions.

Olga Bunimovich, MD, assistant professor, department of dermatology, University of Pittsburgh School of Medicine, Pennsylvania, called this study “an excellent step towards characterizing the role masks play in facial dermatoses.”

“The study provides a window into the prevalence of these conditions, as well as some understanding of the factors that may be contributing to it,” Dr. Bunimovich, who was not part of the study, added. But “we can also utilize this information to alter behavior in the work environment, allowing ‘mask-free’ breaks to decrease the risk of facial dermatoses.”

Elma Baron, MD, professor and director, Skin Study Center, department of dermatology, Case Western Reserve University School of Medicine, Cleveland, expected skin problems to be linked with mask wearing but didn’t expect the prevalence to be as high as 55%, which she called “very significant.”

“Mask wearing is an important means to prevent transmission of communicable infections, and the practice will most likely continue,” she said.

“Given the data, it is reasonable to advise patients who are already prone to these specific dermatoses to be proactive,” she added. “Early intervention with proper topical medications, preferably prescribed by a dermatologist or other health care provider, and changing masks frequently before they get soaked with moisture, will hopefully lessen the severity of skin rashes and minimize the negative impact on quality of life.”

Also commenting on the study, Susan Massick, MD, dermatologist and clinical associate professor of internal medicine, The Ohio State University Wexner Medical Center, Westerville, said in an interview that she urges people to wear masks, despite these risks.

“The majority of concerns are straightforward, manageable, and overall benign,” she said. “We have a multitude of treatments that can help control, address, or improve symptoms.”

“Masks are an effective and easy way to protect yourself from infection, and they remain one of the most reliable preventions we have,” Dr. Massick noted. “The findings in this article should not preclude anyone from wearing a mask, nor should facial dermatoses be a cause for people to stop wearing their masks.”

The study received no funding. The authors, as well as Dr. Baron, Dr. Miller, Dr. Bunimovich, and Dr. Massick, who were not involved in the study, reported no relevant financial relationships. All experts commented by email.

A version of this article first appeared on Medscape.com.

Correction, 9/22/22: An earlier version of this article misstated the name of Dr. Yik Weng Yew.

Around half the people who wear face masks may develop acne, facial dermatitis, itch, or pressure injuries, and the risk increases with the length of time the mask is worn, according to a recently published systematic review and meta-analysis.

“This report finds the most statistically significant risk factor for developing a facial dermatosis under a face mask is how long one wears the mask. Specifically, wearing a mask for more than 4 to 6 hours correlated most strongly with the development of a facial skin problem,” Jami L. Miller, MD, associate professor of dermatology, Vanderbilt University Medical Center, Nashville, Tenn., told this news organization. Dr. Miller was not involved in the study.

“The type of mask and the environment were of less significance,” she added.

UerDomwet/PxHere

• The overall prevalence of facial dermatoses was 55%
• Individually, facial dermatitis, itch, acne, and pressure injuries were consistently reported as facial dermatoses, with pooled prevalence rates of 24%, 30%, 31%, and 31%, respectively
• The duration of mask wearing was the most significant risk factor for facial dermatoses (P < .001)
• Respirators, including N95 masks, were not more likely than surgical masks to be linked with facial dermatoses

“Understanding risk factors of mask wearing, including situation, duration, and type of mask, may allow for targeted interventions to mitigate problems,” Dr. Yew told this news organization.

He advised taking a break from mask wearing after 4 to 6 hours to improve outcomes.  

Dr. Yew acknowledged limitations, including that most of the reviewed studies relied on self-reported symptoms.

“Patient factors were not investigated in most studies; therefore, we were not able to ascertain their contributory role in the development of facial dermatoses from mask wearing,” he said. “We were also unable to prove causation between risk factors and outcome.” 

Four dermatologists welcome the findings

Dr. Miller called this an “interesting, and certainly relevant” study, now that mask wearing is common and facial skin problems are fairly common complaints in medical visits.

“As the authors say, irritants or contact allergens with longer exposures can be expected to cause a more severe dermatitis than short contact,” she said. “Longer duration also can cause occlusion of pores and hair follicles, which can be expected to worsen acne and folliculitis.”

“I was surprised that the type of mask did not seem to matter significantly,” she added. “Patients wearing N95 masks may be relieved to know N95s do not cause more skin problems than lighter masks.”

Still, Dr. Miller had several questions, including if the materials and chemical finishes that vary by manufacturer may affect skin conditions.

Olga Bunimovich, MD, assistant professor, department of dermatology, University of Pittsburgh School of Medicine, Pennsylvania, called this study “an excellent step towards characterizing the role masks play in facial dermatoses.”

“The study provides a window into the prevalence of these conditions, as well as some understanding of the factors that may be contributing to it,” Dr. Bunimovich, who was not part of the study, added. But “we can also utilize this information to alter behavior in the work environment, allowing ‘mask-free’ breaks to decrease the risk of facial dermatoses.”

Elma Baron, MD, professor and director, Skin Study Center, department of dermatology, Case Western Reserve University School of Medicine, Cleveland, expected skin problems to be linked with mask wearing but didn’t expect the prevalence to be as high as 55%, which she called “very significant.”

“Mask wearing is an important means to prevent transmission of communicable infections, and the practice will most likely continue,” she said.

“Given the data, it is reasonable to advise patients who are already prone to these specific dermatoses to be proactive,” she added. “Early intervention with proper topical medications, preferably prescribed by a dermatologist or other health care provider, and changing masks frequently before they get soaked with moisture, will hopefully lessen the severity of skin rashes and minimize the negative impact on quality of life.”

Also commenting on the study, Susan Massick, MD, dermatologist and clinical associate professor of internal medicine, The Ohio State University Wexner Medical Center, Westerville, said in an interview that she urges people to wear masks, despite these risks.

“The majority of concerns are straightforward, manageable, and overall benign,” she said. “We have a multitude of treatments that can help control, address, or improve symptoms.”

“Masks are an effective and easy way to protect yourself from infection, and they remain one of the most reliable preventions we have,” Dr. Massick noted. “The findings in this article should not preclude anyone from wearing a mask, nor should facial dermatoses be a cause for people to stop wearing their masks.”

The study received no funding. The authors, as well as Dr. Baron, Dr. Miller, Dr. Bunimovich, and Dr. Massick, who were not involved in the study, reported no relevant financial relationships. All experts commented by email.

A version of this article first appeared on Medscape.com.

Correction, 9/22/22: An earlier version of this article misstated the name of Dr. Yik Weng Yew.

Around half the people who wear face masks may develop acne, facial dermatitis, itch, or pressure injuries, and the risk increases with the length of time the mask is worn, according to a recently published systematic review and meta-analysis.

“This report finds the most statistically significant risk factor for developing a facial dermatosis under a face mask is how long one wears the mask. Specifically, wearing a mask for more than 4 to 6 hours correlated most strongly with the development of a facial skin problem,” Jami L. Miller, MD, associate professor of dermatology, Vanderbilt University Medical Center, Nashville, Tenn., told this news organization. Dr. Miller was not involved in the study.

“The type of mask and the environment were of less significance,” she added.

UerDomwet/PxHere

• The overall prevalence of facial dermatoses was 55%
• Individually, facial dermatitis, itch, acne, and pressure injuries were consistently reported as facial dermatoses, with pooled prevalence rates of 24%, 30%, 31%, and 31%, respectively
• The duration of mask wearing was the most significant risk factor for facial dermatoses (P < .001)
• Respirators, including N95 masks, were not more likely than surgical masks to be linked with facial dermatoses

“Understanding risk factors of mask wearing, including situation, duration, and type of mask, may allow for targeted interventions to mitigate problems,” Dr. Yew told this news organization.

He advised taking a break from mask wearing after 4 to 6 hours to improve outcomes.  

Dr. Yew acknowledged limitations, including that most of the reviewed studies relied on self-reported symptoms.

“Patient factors were not investigated in most studies; therefore, we were not able to ascertain their contributory role in the development of facial dermatoses from mask wearing,” he said. “We were also unable to prove causation between risk factors and outcome.” 

Four dermatologists welcome the findings

Dr. Miller called this an “interesting, and certainly relevant” study, now that mask wearing is common and facial skin problems are fairly common complaints in medical visits.

“As the authors say, irritants or contact allergens with longer exposures can be expected to cause a more severe dermatitis than short contact,” she said. “Longer duration also can cause occlusion of pores and hair follicles, which can be expected to worsen acne and folliculitis.”

“I was surprised that the type of mask did not seem to matter significantly,” she added. “Patients wearing N95 masks may be relieved to know N95s do not cause more skin problems than lighter masks.”

Still, Dr. Miller had several questions, including if the materials and chemical finishes that vary by manufacturer may affect skin conditions.

Olga Bunimovich, MD, assistant professor, department of dermatology, University of Pittsburgh School of Medicine, Pennsylvania, called this study “an excellent step towards characterizing the role masks play in facial dermatoses.”

“The study provides a window into the prevalence of these conditions, as well as some understanding of the factors that may be contributing to it,” Dr. Bunimovich, who was not part of the study, added. But “we can also utilize this information to alter behavior in the work environment, allowing ‘mask-free’ breaks to decrease the risk of facial dermatoses.”

Elma Baron, MD, professor and director, Skin Study Center, department of dermatology, Case Western Reserve University School of Medicine, Cleveland, expected skin problems to be linked with mask wearing but didn’t expect the prevalence to be as high as 55%, which she called “very significant.”

“Mask wearing is an important means to prevent transmission of communicable infections, and the practice will most likely continue,” she said.

“Given the data, it is reasonable to advise patients who are already prone to these specific dermatoses to be proactive,” she added. “Early intervention with proper topical medications, preferably prescribed by a dermatologist or other health care provider, and changing masks frequently before they get soaked with moisture, will hopefully lessen the severity of skin rashes and minimize the negative impact on quality of life.”

Also commenting on the study, Susan Massick, MD, dermatologist and clinical associate professor of internal medicine, The Ohio State University Wexner Medical Center, Westerville, said in an interview that she urges people to wear masks, despite these risks.

“The majority of concerns are straightforward, manageable, and overall benign,” she said. “We have a multitude of treatments that can help control, address, or improve symptoms.”

“Masks are an effective and easy way to protect yourself from infection, and they remain one of the most reliable preventions we have,” Dr. Massick noted. “The findings in this article should not preclude anyone from wearing a mask, nor should facial dermatoses be a cause for people to stop wearing their masks.”

The study received no funding. The authors, as well as Dr. Baron, Dr. Miller, Dr. Bunimovich, and Dr. Massick, who were not involved in the study, reported no relevant financial relationships. All experts commented by email.

A version of this article first appeared on Medscape.com.

Correction, 9/22/22: An earlier version of this article misstated the name of Dr. Yik Weng Yew.

Atopic dermatitis (AD) and allergic contact dermatitis (ACD) are 2 common inflammatory skin conditions that may have similar clinical presentations. Historically, it was thought that these conditions could not be diagnosed simultaneously due to their differing immune mechanisms; however, this belief has been challenged by recent evidence suggesting a more nuanced relationship between the 2 disease processes. In this review, we examine the complex interplay between AD and ACD and explain how shifts in conventional understanding of the 2 conditions shaped our evolving recognition of their ability to coexist.

Epidemiology of AD and ACD

Atopic dermatitis is the most common inflammatory skin disease in children and adolescents, with an estimated prevalence reaching 21%.¹ In 60% of cases, onset of AD will occur within the first year of life, and 90% of cases begin within the first 5 years.² Resolution may occur by adulthood; however, AD may continue to impact up to 8% to 9% of adults, with an increased prevalence in those older than 75 years.¹ This may represent an underestimation of the burden of adult AD; one systematic review of 17 studies found that the pooled proportion of adult-onset AD was greater than 25%.³

In contrast, ACD previously was assumed to be a disease that more commonly impacted adults and only rarely children, primarily due to an early misconception that children were not frequently exposed to contact allergens and their immune systems were too immature to react to them even if exposed.^4,5 However, it is now known that children do have risk factors for development of ACD, including a thinner stratum corneum and potentially a more absorbent skin surface.⁴ In addition, a 2022 study by the North American Contact Dermatitis Group (NACDG) found similar rates of ACD in children (n=1871) and adults (n=41,699) referred for patch testing (55.2% and 57.3%, respectively) as well as similar rates of having at least 1 relevant positive patch test (49.2% and 52.2%).⁶

In opposition to traditional beliefs, these findings highlight that AD and ACD can occur across age groups.

Immune Mechanism

The pathogenesis of AD represents a multifactorial process involving the immune system, cutaneous flora, genetic predisposition, and surrounding environment. Immunologically, acute AD is driven by a predominantly T_H2 helper T-cell response with high levels of IL-4, IL-5, and IL-13⁷; T_H22, T_H17, and T_H1 also have been implicated.⁸ Notably, T_H17 is found in high levels during the acute eczema phase, while T_H1 and T_H22are associated with the chronic phase.⁷

The pathophysiology of ACD is not completely understood. The classic paradigm involves 2 phases: sensitization and elicitation. Sensitization involves antigen-presenting cells that take up allergens absorbed by the skin to present them in regional lymph nodes where antigen-specific T lymphocytes are generated. Elicitation occurs upon re-exposure to the allergen, at which time the primed T lymphocytes are recruited to the skin, causing inflammation.⁹ Allergic contact dermatitis initially was thought to be driven by T_H1 cytokines and IL-17 but now is understood to be more complex.¹⁰ Studies have revealed immune polarization of contact allergens, demonstrating that nickel primarily induces a T_H1/T_H17 response, whereas fragrance and rubber accelerators skew to T_H2; T_H9 and T_H22 also may be involved depending on the causative allergen.^11,12

Of note, the immunologic differences between AD and ACD led early investigators to believe that patients with AD were relatively protected from ACD.¹³ However, as previously described, there are several overlapping cytokines between AD and ACD. Furthermore, research has revealed that risk of contact sensitization might be increased in the chronic eczema phase due to the shared T_H1 pathway.¹⁴ Barrier-disrupted skin (such as that in AD) also may increase the cytokine response and the density of antigen-presenting cells, leading to a proallergic state.¹⁵ This suggests that the immunologic pathways of AD and ACD are more intertwined than was previously understood.

Underlying Risk Factors

Skin barrier dysfunction is a key step in the pathogenesis of AD. Patients with AD commonly have loss-of-function mutations in the filaggrin gene, a protein that is key to the function of the stratum corneum. Loss of this protein may not only impact the immune response as previously noted but also may lead to increased transepidermal water loss and bacterial colonization.¹⁶ Interestingly, a 2014 review examined how this mutation could lead to an increased risk of sensitization to bivalent metal ions via an impaired chelating ability of the skin.¹⁷ Furthermore, a 2016 study conducted in Dutch construction workers revealed an increased risk for contact dermatitis (irritant and allergic) for those with a loss-of-function filaggrin mutation.¹⁸

Importantly, this same mutation may explain why patients with AD tend to have increased skin colonization by Staphylococcus aureus. The abundance of S aureus and the relative decrease in the diversity of other microorganisms on the skin may be associated with increased AD severity.¹⁹ Likewise, S aureus may play a role in the pathogenesis of ACD via production of its exotoxin directed at the T-cell receptor V beta 17 region. In particular, this receptor has been associated with nickel sensitization.¹⁷

Another risk factor to consider is increased exposure to contact sensitizers when treating AD. For instance, management often includes use of over-the-counter emollients, natural or botanical remedies with purported benefits for AD, cleansers, and detergents. However, these products can contain some of the most prevalent contact allergens seen in those with AD, including methyl-isothiazolinone, formaldehyde releasers, and fragrance.²⁰ Topical corticosteroids also are frequently used, and ACD to steroid molecules can occur, particularly to tixocortol-21-pivalate (a marker for class A corticosteroids) and budesonide (a marker for class B corticosteroids).²¹ Other allergens (eg, benzyl alcohol, propylene glycol) also may be found as inactive ingredients of topical corticosteroids.²² These exposures may place AD patients at risk for ACD.

The Coexistence of AD and ACD

Given the overlapping epidemiology, immunology, and potentially increased risk for the development of ACD in patients with AD, it would be reasonable to assume that the 2 diagnoses could coexist; however, is there clinical data to support this idea? Based on recent database reviews, the answer appears to be yes.^20,23-26 An analysis from the Pediatric Contact Dermatitis Registry revealed that 30% of 1142 pediatric patch test cases analyzed were diagnosed as AD and ACD simultaneously.²⁴ The NACDG found similar results in its 2021 review, as 29.5% of children (n=1648) and 20.7% of adults (n=36,834) had a concurrent diagnosis of AD and ACD.²⁰ Notably, older results from these databases also demonstrated an association between the 2 conditions.^23,25,26

It remains unclear whether the prevalence of ACD is higher in those with or without AD. A comprehensive systematic review conducted in 2017 examined this topic through analysis of 74 studies. The results demonstrated a similar prevalence of contact sensitization in individuals with and without AD.²⁷ Another systematic review of 31 studies conducted in 2017 found a higher prevalence for ACD in children without AD; however, the authors noted that the included studies were too variable (eg, size, design, allergens tested) to draw definitive conclusions.²⁸

Even though there is no clear overall increased risk for ACD in patients with AD, research has suggested that certain allergens may be more prevalent in the setting of AD. An NACDG study found that adults with AD had increased odds of reacting to 10 of the top 25 NACDG screening allergens compared to those without AD.²⁰ Other studies have found that AD patients may be more likely to become sensitized to certain allergens, such as fragrance and lanolin.¹⁴

Considerations for Management

Diagnosis of ACD in patients with AD can be challenging because these conditions may present similarly with chronic, pruritic, inflammatory patches and plaques. Chronic ACD may be misdiagnosed as AD if patch testing is not performed.²⁹ Given the prevalence of ACD in the setting of AD, there should be a low threshold to pursue patch testing, especially when dermatitis is recalcitrant to standard therapies or presents in an atypical distribution (ie, perioral, predominantly head/neck, hand and foot, isolated eyelid involvement, buttocks).^4,30 Various allergen series are available for patch testing adults and children including the NACDG Standard Series, American Contact Dermatitis Society Core Allergen Series, or the Pediatric Baseline Series.^31-33

If potentially relevant allergens are uncovered by patch testing, patients should be counseled on avoidance strategies. However, allergen avoidance may not always lead to complete symptom resolution, especially if AD is present concomitantly with ACD. Therefore, use of topical or systemic therapies still may be required. Topical corticosteroids can be used when dermatitis is acute and localized. Systemic corticosteroids are utilized for both diagnoses when cases are more severe or extensive, but their adverse-effect profile limits long-term use. Other systemic treatments, including conventional agents (ie, azathioprine, cyclosporine, methotrexate, mycophenolate mofetil), biologics, and small molecule inhibitors also may be considered for severe cases.^34,35 Dupilumab, a monoclonal antibody targeting IL-4/IL-13, is approved for use in moderate to severe AD in patients 6 months and older. Recent evidence has suggested that dupilumab also may be an effective off-label treatment choice for ACD when allergen avoidance alone is insufficient.³⁶ Studies have been conducted on secukinumab, a monoclonal antibody against IL-17; however, it has not been shown to be effective in either AD or ACD.^37,38 This indicates that targeted biologics may not always be successful in treating these diagnoses, likely due to their complex immune pathways. Finally, there is an emerging role for JAK inhibitors. Three are approved for AD: topical ruxolitinib, oral abrocitinib, and oral upadacitinib.³⁹ Further investigation is needed to determine the efficacy of JAK inhibitors in ACD.

Final Interpretation

Evolving evidence shows that AD and ACD can occur at the same time despite the historical perspective that their immune pathways were too polarized for this to happen. Atopic dermatitis may be an important risk factor for subsequent development of ACD. Management should include a low threshold to perform patch testing, while pharmacotherapies utilized in the treatment of both conditions should be considered.

Atopic dermatitis (AD) and allergic contact dermatitis (ACD) are 2 common inflammatory skin conditions that may have similar clinical presentations. Historically, it was thought that these conditions could not be diagnosed simultaneously due to their differing immune mechanisms; however, this belief has been challenged by recent evidence suggesting a more nuanced relationship between the 2 disease processes. In this review, we examine the complex interplay between AD and ACD and explain how shifts in conventional understanding of the 2 conditions shaped our evolving recognition of their ability to coexist.

Epidemiology of AD and ACD

Atopic dermatitis is the most common inflammatory skin disease in children and adolescents, with an estimated prevalence reaching 21%.¹ In 60% of cases, onset of AD will occur within the first year of life, and 90% of cases begin within the first 5 years.² Resolution may occur by adulthood; however, AD may continue to impact up to 8% to 9% of adults, with an increased prevalence in those older than 75 years.¹ This may represent an underestimation of the burden of adult AD; one systematic review of 17 studies found that the pooled proportion of adult-onset AD was greater than 25%.³

In contrast, ACD previously was assumed to be a disease that more commonly impacted adults and only rarely children, primarily due to an early misconception that children were not frequently exposed to contact allergens and their immune systems were too immature to react to them even if exposed.^4,5 However, it is now known that children do have risk factors for development of ACD, including a thinner stratum corneum and potentially a more absorbent skin surface.⁴ In addition, a 2022 study by the North American Contact Dermatitis Group (NACDG) found similar rates of ACD in children (n=1871) and adults (n=41,699) referred for patch testing (55.2% and 57.3%, respectively) as well as similar rates of having at least 1 relevant positive patch test (49.2% and 52.2%).⁶

In opposition to traditional beliefs, these findings highlight that AD and ACD can occur across age groups.

Immune Mechanism

The pathogenesis of AD represents a multifactorial process involving the immune system, cutaneous flora, genetic predisposition, and surrounding environment. Immunologically, acute AD is driven by a predominantly T_H2 helper T-cell response with high levels of IL-4, IL-5, and IL-13⁷; T_H22, T_H17, and T_H1 also have been implicated.⁸ Notably, T_H17 is found in high levels during the acute eczema phase, while T_H1 and T_H22are associated with the chronic phase.⁷

The pathophysiology of ACD is not completely understood. The classic paradigm involves 2 phases: sensitization and elicitation. Sensitization involves antigen-presenting cells that take up allergens absorbed by the skin to present them in regional lymph nodes where antigen-specific T lymphocytes are generated. Elicitation occurs upon re-exposure to the allergen, at which time the primed T lymphocytes are recruited to the skin, causing inflammation.⁹ Allergic contact dermatitis initially was thought to be driven by T_H1 cytokines and IL-17 but now is understood to be more complex.¹⁰ Studies have revealed immune polarization of contact allergens, demonstrating that nickel primarily induces a T_H1/T_H17 response, whereas fragrance and rubber accelerators skew to T_H2; T_H9 and T_H22 also may be involved depending on the causative allergen.^11,12

Of note, the immunologic differences between AD and ACD led early investigators to believe that patients with AD were relatively protected from ACD.¹³ However, as previously described, there are several overlapping cytokines between AD and ACD. Furthermore, research has revealed that risk of contact sensitization might be increased in the chronic eczema phase due to the shared T_H1 pathway.¹⁴ Barrier-disrupted skin (such as that in AD) also may increase the cytokine response and the density of antigen-presenting cells, leading to a proallergic state.¹⁵ This suggests that the immunologic pathways of AD and ACD are more intertwined than was previously understood.

Underlying Risk Factors

Skin barrier dysfunction is a key step in the pathogenesis of AD. Patients with AD commonly have loss-of-function mutations in the filaggrin gene, a protein that is key to the function of the stratum corneum. Loss of this protein may not only impact the immune response as previously noted but also may lead to increased transepidermal water loss and bacterial colonization.¹⁶ Interestingly, a 2014 review examined how this mutation could lead to an increased risk of sensitization to bivalent metal ions via an impaired chelating ability of the skin.¹⁷ Furthermore, a 2016 study conducted in Dutch construction workers revealed an increased risk for contact dermatitis (irritant and allergic) for those with a loss-of-function filaggrin mutation.¹⁸

Importantly, this same mutation may explain why patients with AD tend to have increased skin colonization by Staphylococcus aureus. The abundance of S aureus and the relative decrease in the diversity of other microorganisms on the skin may be associated with increased AD severity.¹⁹ Likewise, S aureus may play a role in the pathogenesis of ACD via production of its exotoxin directed at the T-cell receptor V beta 17 region. In particular, this receptor has been associated with nickel sensitization.¹⁷

Another risk factor to consider is increased exposure to contact sensitizers when treating AD. For instance, management often includes use of over-the-counter emollients, natural or botanical remedies with purported benefits for AD, cleansers, and detergents. However, these products can contain some of the most prevalent contact allergens seen in those with AD, including methyl-isothiazolinone, formaldehyde releasers, and fragrance.²⁰ Topical corticosteroids also are frequently used, and ACD to steroid molecules can occur, particularly to tixocortol-21-pivalate (a marker for class A corticosteroids) and budesonide (a marker for class B corticosteroids).²¹ Other allergens (eg, benzyl alcohol, propylene glycol) also may be found as inactive ingredients of topical corticosteroids.²² These exposures may place AD patients at risk for ACD.

The Coexistence of AD and ACD

Given the overlapping epidemiology, immunology, and potentially increased risk for the development of ACD in patients with AD, it would be reasonable to assume that the 2 diagnoses could coexist; however, is there clinical data to support this idea? Based on recent database reviews, the answer appears to be yes.^20,23-26 An analysis from the Pediatric Contact Dermatitis Registry revealed that 30% of 1142 pediatric patch test cases analyzed were diagnosed as AD and ACD simultaneously.²⁴ The NACDG found similar results in its 2021 review, as 29.5% of children (n=1648) and 20.7% of adults (n=36,834) had a concurrent diagnosis of AD and ACD.²⁰ Notably, older results from these databases also demonstrated an association between the 2 conditions.^23,25,26

It remains unclear whether the prevalence of ACD is higher in those with or without AD. A comprehensive systematic review conducted in 2017 examined this topic through analysis of 74 studies. The results demonstrated a similar prevalence of contact sensitization in individuals with and without AD.²⁷ Another systematic review of 31 studies conducted in 2017 found a higher prevalence for ACD in children without AD; however, the authors noted that the included studies were too variable (eg, size, design, allergens tested) to draw definitive conclusions.²⁸

Even though there is no clear overall increased risk for ACD in patients with AD, research has suggested that certain allergens may be more prevalent in the setting of AD. An NACDG study found that adults with AD had increased odds of reacting to 10 of the top 25 NACDG screening allergens compared to those without AD.²⁰ Other studies have found that AD patients may be more likely to become sensitized to certain allergens, such as fragrance and lanolin.¹⁴

Considerations for Management

Diagnosis of ACD in patients with AD can be challenging because these conditions may present similarly with chronic, pruritic, inflammatory patches and plaques. Chronic ACD may be misdiagnosed as AD if patch testing is not performed.²⁹ Given the prevalence of ACD in the setting of AD, there should be a low threshold to pursue patch testing, especially when dermatitis is recalcitrant to standard therapies or presents in an atypical distribution (ie, perioral, predominantly head/neck, hand and foot, isolated eyelid involvement, buttocks).^4,30 Various allergen series are available for patch testing adults and children including the NACDG Standard Series, American Contact Dermatitis Society Core Allergen Series, or the Pediatric Baseline Series.^31-33

If potentially relevant allergens are uncovered by patch testing, patients should be counseled on avoidance strategies. However, allergen avoidance may not always lead to complete symptom resolution, especially if AD is present concomitantly with ACD. Therefore, use of topical or systemic therapies still may be required. Topical corticosteroids can be used when dermatitis is acute and localized. Systemic corticosteroids are utilized for both diagnoses when cases are more severe or extensive, but their adverse-effect profile limits long-term use. Other systemic treatments, including conventional agents (ie, azathioprine, cyclosporine, methotrexate, mycophenolate mofetil), biologics, and small molecule inhibitors also may be considered for severe cases.^34,35 Dupilumab, a monoclonal antibody targeting IL-4/IL-13, is approved for use in moderate to severe AD in patients 6 months and older. Recent evidence has suggested that dupilumab also may be an effective off-label treatment choice for ACD when allergen avoidance alone is insufficient.³⁶ Studies have been conducted on secukinumab, a monoclonal antibody against IL-17; however, it has not been shown to be effective in either AD or ACD.^37,38 This indicates that targeted biologics may not always be successful in treating these diagnoses, likely due to their complex immune pathways. Finally, there is an emerging role for JAK inhibitors. Three are approved for AD: topical ruxolitinib, oral abrocitinib, and oral upadacitinib.³⁹ Further investigation is needed to determine the efficacy of JAK inhibitors in ACD.

Final Interpretation

Evolving evidence shows that AD and ACD can occur at the same time despite the historical perspective that their immune pathways were too polarized for this to happen. Atopic dermatitis may be an important risk factor for subsequent development of ACD. Management should include a low threshold to perform patch testing, while pharmacotherapies utilized in the treatment of both conditions should be considered.

Atopic dermatitis (AD) and allergic contact dermatitis (ACD) are 2 common inflammatory skin conditions that may have similar clinical presentations. Historically, it was thought that these conditions could not be diagnosed simultaneously due to their differing immune mechanisms; however, this belief has been challenged by recent evidence suggesting a more nuanced relationship between the 2 disease processes. In this review, we examine the complex interplay between AD and ACD and explain how shifts in conventional understanding of the 2 conditions shaped our evolving recognition of their ability to coexist.

Epidemiology of AD and ACD

Atopic dermatitis is the most common inflammatory skin disease in children and adolescents, with an estimated prevalence reaching 21%.¹ In 60% of cases, onset of AD will occur within the first year of life, and 90% of cases begin within the first 5 years.² Resolution may occur by adulthood; however, AD may continue to impact up to 8% to 9% of adults, with an increased prevalence in those older than 75 years.¹ This may represent an underestimation of the burden of adult AD; one systematic review of 17 studies found that the pooled proportion of adult-onset AD was greater than 25%.³

In contrast, ACD previously was assumed to be a disease that more commonly impacted adults and only rarely children, primarily due to an early misconception that children were not frequently exposed to contact allergens and their immune systems were too immature to react to them even if exposed.^4,5 However, it is now known that children do have risk factors for development of ACD, including a thinner stratum corneum and potentially a more absorbent skin surface.⁴ In addition, a 2022 study by the North American Contact Dermatitis Group (NACDG) found similar rates of ACD in children (n=1871) and adults (n=41,699) referred for patch testing (55.2% and 57.3%, respectively) as well as similar rates of having at least 1 relevant positive patch test (49.2% and 52.2%).⁶

In opposition to traditional beliefs, these findings highlight that AD and ACD can occur across age groups.

Immune Mechanism

The pathogenesis of AD represents a multifactorial process involving the immune system, cutaneous flora, genetic predisposition, and surrounding environment. Immunologically, acute AD is driven by a predominantly T_H2 helper T-cell response with high levels of IL-4, IL-5, and IL-13⁷; T_H22, T_H17, and T_H1 also have been implicated.⁸ Notably, T_H17 is found in high levels during the acute eczema phase, while T_H1 and T_H22are associated with the chronic phase.⁷

The pathophysiology of ACD is not completely understood. The classic paradigm involves 2 phases: sensitization and elicitation. Sensitization involves antigen-presenting cells that take up allergens absorbed by the skin to present them in regional lymph nodes where antigen-specific T lymphocytes are generated. Elicitation occurs upon re-exposure to the allergen, at which time the primed T lymphocytes are recruited to the skin, causing inflammation.⁹ Allergic contact dermatitis initially was thought to be driven by T_H1 cytokines and IL-17 but now is understood to be more complex.¹⁰ Studies have revealed immune polarization of contact allergens, demonstrating that nickel primarily induces a T_H1/T_H17 response, whereas fragrance and rubber accelerators skew to T_H2; T_H9 and T_H22 also may be involved depending on the causative allergen.^11,12

Of note, the immunologic differences between AD and ACD led early investigators to believe that patients with AD were relatively protected from ACD.¹³ However, as previously described, there are several overlapping cytokines between AD and ACD. Furthermore, research has revealed that risk of contact sensitization might be increased in the chronic eczema phase due to the shared T_H1 pathway.¹⁴ Barrier-disrupted skin (such as that in AD) also may increase the cytokine response and the density of antigen-presenting cells, leading to a proallergic state.¹⁵ This suggests that the immunologic pathways of AD and ACD are more intertwined than was previously understood.

Underlying Risk Factors

Skin barrier dysfunction is a key step in the pathogenesis of AD. Patients with AD commonly have loss-of-function mutations in the filaggrin gene, a protein that is key to the function of the stratum corneum. Loss of this protein may not only impact the immune response as previously noted but also may lead to increased transepidermal water loss and bacterial colonization.¹⁶ Interestingly, a 2014 review examined how this mutation could lead to an increased risk of sensitization to bivalent metal ions via an impaired chelating ability of the skin.¹⁷ Furthermore, a 2016 study conducted in Dutch construction workers revealed an increased risk for contact dermatitis (irritant and allergic) for those with a loss-of-function filaggrin mutation.¹⁸

Importantly, this same mutation may explain why patients with AD tend to have increased skin colonization by Staphylococcus aureus. The abundance of S aureus and the relative decrease in the diversity of other microorganisms on the skin may be associated with increased AD severity.¹⁹ Likewise, S aureus may play a role in the pathogenesis of ACD via production of its exotoxin directed at the T-cell receptor V beta 17 region. In particular, this receptor has been associated with nickel sensitization.¹⁷

Another risk factor to consider is increased exposure to contact sensitizers when treating AD. For instance, management often includes use of over-the-counter emollients, natural or botanical remedies with purported benefits for AD, cleansers, and detergents. However, these products can contain some of the most prevalent contact allergens seen in those with AD, including methyl-isothiazolinone, formaldehyde releasers, and fragrance.²⁰ Topical corticosteroids also are frequently used, and ACD to steroid molecules can occur, particularly to tixocortol-21-pivalate (a marker for class A corticosteroids) and budesonide (a marker for class B corticosteroids).²¹ Other allergens (eg, benzyl alcohol, propylene glycol) also may be found as inactive ingredients of topical corticosteroids.²² These exposures may place AD patients at risk for ACD.

The Coexistence of AD and ACD

Given the overlapping epidemiology, immunology, and potentially increased risk for the development of ACD in patients with AD, it would be reasonable to assume that the 2 diagnoses could coexist; however, is there clinical data to support this idea? Based on recent database reviews, the answer appears to be yes.^20,23-26 An analysis from the Pediatric Contact Dermatitis Registry revealed that 30% of 1142 pediatric patch test cases analyzed were diagnosed as AD and ACD simultaneously.²⁴ The NACDG found similar results in its 2021 review, as 29.5% of children (n=1648) and 20.7% of adults (n=36,834) had a concurrent diagnosis of AD and ACD.²⁰ Notably, older results from these databases also demonstrated an association between the 2 conditions.^23,25,26

It remains unclear whether the prevalence of ACD is higher in those with or without AD. A comprehensive systematic review conducted in 2017 examined this topic through analysis of 74 studies. The results demonstrated a similar prevalence of contact sensitization in individuals with and without AD.²⁷ Another systematic review of 31 studies conducted in 2017 found a higher prevalence for ACD in children without AD; however, the authors noted that the included studies were too variable (eg, size, design, allergens tested) to draw definitive conclusions.²⁸

Even though there is no clear overall increased risk for ACD in patients with AD, research has suggested that certain allergens may be more prevalent in the setting of AD. An NACDG study found that adults with AD had increased odds of reacting to 10 of the top 25 NACDG screening allergens compared to those without AD.²⁰ Other studies have found that AD patients may be more likely to become sensitized to certain allergens, such as fragrance and lanolin.¹⁴

Considerations for Management

Diagnosis of ACD in patients with AD can be challenging because these conditions may present similarly with chronic, pruritic, inflammatory patches and plaques. Chronic ACD may be misdiagnosed as AD if patch testing is not performed.²⁹ Given the prevalence of ACD in the setting of AD, there should be a low threshold to pursue patch testing, especially when dermatitis is recalcitrant to standard therapies or presents in an atypical distribution (ie, perioral, predominantly head/neck, hand and foot, isolated eyelid involvement, buttocks).^4,30 Various allergen series are available for patch testing adults and children including the NACDG Standard Series, American Contact Dermatitis Society Core Allergen Series, or the Pediatric Baseline Series.^31-33

If potentially relevant allergens are uncovered by patch testing, patients should be counseled on avoidance strategies. However, allergen avoidance may not always lead to complete symptom resolution, especially if AD is present concomitantly with ACD. Therefore, use of topical or systemic therapies still may be required. Topical corticosteroids can be used when dermatitis is acute and localized. Systemic corticosteroids are utilized for both diagnoses when cases are more severe or extensive, but their adverse-effect profile limits long-term use. Other systemic treatments, including conventional agents (ie, azathioprine, cyclosporine, methotrexate, mycophenolate mofetil), biologics, and small molecule inhibitors also may be considered for severe cases.^34,35 Dupilumab, a monoclonal antibody targeting IL-4/IL-13, is approved for use in moderate to severe AD in patients 6 months and older. Recent evidence has suggested that dupilumab also may be an effective off-label treatment choice for ACD when allergen avoidance alone is insufficient.³⁶ Studies have been conducted on secukinumab, a monoclonal antibody against IL-17; however, it has not been shown to be effective in either AD or ACD.^37,38 This indicates that targeted biologics may not always be successful in treating these diagnoses, likely due to their complex immune pathways. Finally, there is an emerging role for JAK inhibitors. Three are approved for AD: topical ruxolitinib, oral abrocitinib, and oral upadacitinib.³⁹ Further investigation is needed to determine the efficacy of JAK inhibitors in ACD.

Final Interpretation

Evolving evidence shows that AD and ACD can occur at the same time despite the historical perspective that their immune pathways were too polarized for this to happen. Atopic dermatitis may be an important risk factor for subsequent development of ACD. Management should include a low threshold to perform patch testing, while pharmacotherapies utilized in the treatment of both conditions should be considered.