Contact sensitization to benzoyl peroxide.

The incidence of contact allergy to a 5% benzoyl peroxide (BP) gel has been studied by patch testing in 222 patients. Positive allergic reactions to BP were found in 3.1% of cases in a general clinical population (94 patients), whereas 5.8% of 69 patients with eczematous dermatoses were found to be BP-sensitized. In a group of acne vulgaris patients having used a commercial 5% or 10% BP gel for a period of 12 days to 3 1/2 years (mean: 10.7 months), positive allergic reactions were found in three cases (5.1%).