IS BENZALKONIUM CHLORIDE A RELEVANT CONTA CT ALLERGEN OR IRRITANT - RESULTS OF A MULTICENTER STUDY CONDUCTED BY GERMAN CONTACT ALLERGY GROUP (DKG)

At eight dermatological clinics, a total of 2146 patients were tested between May 1990 and December 1991 to determine the significance of th e preservative benzalkonium chloride in inducing allergic contact derm atitis and to evaluate recommendations for patch testing. In 225 cases an allergic reaction was proven, with 258 irritant reactions in addit ion. Only 12 cases were clinically relevant. Therefore, benzalkonium c hloride is considered a weak allergen. A doubtful (erythema) or an inc ipient positive (with occasional papules) reaction may be regarded as an irritant reaction. In isolated cases, a ''repeated open application test'' (ROAT) should be applied to determine clinical relevance. Our recommendation for patch testing is 0.1% benzalkonium chloride in vase line, and also in water for special cases.