Two cases are reported of allergic contact dermatitis to acne preparations containing benzoyl peroxide. Both patients had positive patch tests to 5% benzoyl peroxide in petrolatum while 40 of 41 control patients had no reaction.
Eaglstein WH. Allergic Contact Dermatitis to Benzoyl PeroxideReport of Cases. Arch Dermatol. 1968;97(5):527. doi:10.1001/archderm.1968.01610110035004