Allergic Contact Dermatitis: New Culprits

New allergens responsible for contact dermatitis emerge regularly. During the Dermatology Days of Paris 2024 conference, Angèle Soria, MD, PhD, a dermatologist at Tenon Hospital in Paris, France, outlined four major categories driving this trend. Among them are (meth)acrylates found in nail cosmetics used in salons or do-it-yourself false nail kits that can be bought online.

Isothiazolinones

While the prevalence of allergic contact dermatitis remains stable at around 20% of the population, new allergens are introduced due to changes in cosmetic formulations and evolving consumer habits. Recent culprits include methylisothiazolinone (MI), a preservative used in many cosmetics; (meth)acrylates; essential oils; and epoxy resins used in industry and leisure activities.

Around 15 years ago, parabens, commonly used as preservatives in cosmetics, were identified as endocrine disruptors. In response, they were largely replaced by newer preservatives, notably MI. However, this led to a proliferation of allergic contact dermatitis in Europe between 2010 and 2013.

“About 10% of the population that we tested showed allergies to these preservatives, primarily found in cosmetics,” explained Soria. Since 2015, the use of MI in leave-on cosmetics has been prohibited in Europe and its concentration restricted in rinse-off products. However, cosmetics sold online from outside Europe may not comply with these regulations.

MI is also present in water-based paints to prevent mold. “A few years ago, we started seeing patients with facial angioedema, sometimes combined with asthma, caused by these isothiazolinone preservatives, including in patients who are not professional painters,” said Soria. More recently, attention has shifted to MI’s presence in household cleaning products. A 2020 Spanish study found MI in 76% of 34 analyzed cleaning products.

MI-based fungicides are also used to treat leather during transport, which can lead to contact allergies among professionals and consumers alike. Additionally, MI has been identified in children’s toys, including slime gels, and in florists’ gel cubes used to preserve flowers.

“We are therefore surrounded by these preservatives, which are no longer only in cosmetics,” warned the dermatologist.

(Meth)acrylates

Another major allergen category is (meth)acrylates, responsible for many cases of allergic contact dermatitis. Acrylates and their derivatives are widely used in everyday items. They are low–molecular weight monomers, sensitizing on contact with the skin. Their polymerized forms include materials like Plexiglas.

“We are currently witnessing an epidemic of contact dermatitis in the general population, mainly due to nail cosmetics, such as semipermanent nail polishes and at-home false nail kits,” reported Soria. Nail cosmetics account for 97% of new sensitization cases involving (meth)acrylates. These allergens often cause severe dermatitis, prompting the European Union to mandate labeling in 2020, warning that these products are “for professional use only” and can “cause allergic reactions.”

Beyond nail cosmetics, these allergens are also found in dental products (such as trays), ECG electrodes, prosthetics, glucose sensors, surgical adhesives, and some electronic devices like earbuds and phone screens. Notably, patients sensitized to acrylates via nail kits may experience reactions during dental treatments involving acrylates.

Investigating Essential Oil Use

Essential oils, distinct from vegetable oils like almond or argan, are another known allergen. Often considered risk-free due to their “natural” label, these products are widely used topically, orally, or via inhalation for various purposes, such as treating respiratory infections or creating relaxing atmospheres. However, essential oils contain fragrant molecules like terpenes, which can become highly allergenic over time, especially after repeated exposure.

Soria emphasized the importance of asking patients about their use of essential oils, especially tea tree and lavender oils, which are commonly used but rarely mentioned by patients unless prompted.

Epoxy Resins in Recreational Use

Epoxy resins are a growing cause of contact allergies, not just in professional settings such as aeronautics and construction work but also increasingly in recreational activities. Soria highlighted the case of a 12-year-old girl hospitalized for severe facial edema after engaging in resin crafts inspired by TikTok. For 6 months, she had been creating resin objects, such as bowls and cutting boards, using vinyl gloves and a Filtering FacePiece 2 mask under adult supervision.

“The growing popularity and online availability of epoxy resins mean that allergic reactions should now be considered even in nonprofessional contexts,” warned Soria.

Clinical Approach

When dermatologists suspect allergic contact dermatitis, the first step is to treat the condition with corticosteroid creams. This is followed by a detailed patient interview to identify suspected allergens in products they’ve used.

Patch testing is then conducted to confirm the allergen. Small chambers containing potential allergens are applied to the upper back for 48 hours without removal. Results are read 2-5 days later, with some cases requiring a 7-day follow-up.

The patient’s occupation is an important factor, as certain professions, such as hairdressing, healthcare, or beauty therapy, are known to trigger allergic contact dermatitis. Similarly, certain hobbies may also play a role. 

A thorough approach ensures accurate diagnosis and targeted prevention strategies.

This story was translated fromMedscape’s French edition using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.