Compared with patients without rosacea, patients with rosacea are more likely to have an allergic reaction to chemical cosmetic ingredients, including octyl gallate, dodecyl gallate, tert-Butylhydroquinone, thimerosal, euxyl K400, cocamido-propyl betaine, and 2,6-Di-tert-butyl-4-cresol, according to a study published in the Journal of Cosmetic Dermatology.

A series of patients with rosacea of the face (n=103; 35 men and 68 women), as well as age- and sex-matched control patients (n=104) who were admitted to an outpatient dermatology clinic in Turkey were enrolled. Participants underwent 48-hour patch testing to the upper back with 49 cosmetic allergens. Test reactions were categorized on a 3-point scale and included weak reaction (papules with erythema; 1+), strong reaction (papules plus edema or vesiculation; 2+), or extreme reaction (spreading papulovesicles or bullae; 3+). Reactions were compared between the 2 groups to determine prevalence of contact sensitization in patients with and without rosacea.

A higher proportion of participants with rosacea had ≥1 positive allergic reaction compared with control patients (60.2% vs 24.0%, respectively). Individuals with rosacea were more likely to have a positive allergic patch-test reaction compared with control patients (P <.001). In addition, a greater proportion of patients in the rosacea group had >1 positive reaction to the applied allergens (39.8% vs 13.5%, respectively; P <.001). The cosmetic allergens most frequently associated with positive test results included octyl gallate (10.68%), dodecyl gallate (8.74%), tert-Butylhydroquinone (7.77%), thimerosal (6.80%), euxyl K400 (6.80%), cocamido-propyl betaine (5.83%), and 2,6-Di-tert-butyl-4-cresol (4.85%).

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Limitations of the study included the small sample size, as well as the inclusion of patients from a single center in Turkey.

“Given that most of the allergic reactions identified in patients were weak reactions,” the researchers wrote, “it should also be considered whether mild forms of contact hypersensitivity may mimic or trigger the exacerbation of the underlying rosacea in patients.”

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Reference

Ozbagcivan O, Akarsu S, Dolas N, Fetil E. Contact sensitization to cosmetic series of allergens in patients with rosacea: A prospective controlled study [published online May 20, 2019]. J Cosmet Dermatol. doi:10.1111/jocd.12989