[Post-therapeutic benzoyl peroxide contact allergy in ulcus cruris patients].

Of 739 dermatitis patients, 4.1% showed a positive patch test reaction to benzoyl peroxide 1% in petrolatum. Forty-one patients with leg ulcers (patch test: negative to benzoyl peroxide) were treated with a 20% benzoyl peroxide emulsion for 4 weeks. After this therapy, the sensitization rate was as high as that for the maximization test, namely 76%. In most patients, the post-therapeutic allergy to benzoyl peroxide was accompanied by contact allergies to other therapeutic agents applied. Only 9 of 31 sensitized patients showed a monovalent benzoyl peroxide allergy. From the allergologic point of view, benzoyl peroxide cannot be recommended for the treatment of leg ulcers. However, there appears to be no danger in the treatment of acne vulgaris.