Hair cosmetics, such as dyes and bleaches are composed of numerous chemical ingredients. Yet, allergic reactions to these contact allergens, other than those with p-phenylenediamine, are rarely reported.

A new study published in Contact Dermatitis aimed to determine the incidence of patch test reactions to hair cosmetic allergens and identify the factors associated with hair cosmetic allergy.

This was a retrospective study that reviewed case records of patients who underwent patch testing from 2009-2018. Patients with at least one positive patch-test to a potential contact allergen associated with hair cosmetic ingredients, were studied.

The results revealed that of hair cosmetic allergen categories, preservatives had the highest rate of positive reactions followed by surfactants and hair dyes. While perming agents were comparativelyless allergenic.Hands, head and neck were predominately affected sites of allergic reactions to hair cosmetic ingredients.

The findings indicated that preservatives, surfactants and hair dyes are important contact allergens, whereas perming agents are less likely to cause allergic reactions. It was stated that continuous observation of hair cosmetic allergy is needed to provide the best patient care.