[Allergic contact dermatitis due to topical imidazole antimycotics. The sensitizing ability of active ingredients and...

Since the introduction of clotrimazole cream to the Japanese market in 1979, topical imidazole antimycotics have been used with increasing frequency in the treatment of superficial fungal infections. Topical imidazole antimycotics are in common use today and new imidazole derivatives continue to be developed. In this study, the author discussed allergic contact dermatitis due to topical imidazole antimycotics and cross-reactions among them. Of the 3,049 outpatients who were patch-tested for contact dermatitis at the Department of Dermatology, Nippon Medical School Hospital from January, 1984 to August, 1994, 218 were patch-tested with topical antimycotic agents. Of these 218 cases, 18 were tested with imidazole derivatives and 66 showed positive. Thirty-five were allergic to the active ingredients; 16 were allergic to sulconazole, 11 to croconazole, 3 to tioconazole, 3 to miconazole, one to bifonazole, and one to clotrimazole. The reason why sulconazole induced the most frequent positive reactions is probably that sulconazole was prescribed most frequently at our department during the period. The duration and the total amount of topical imidazole needed until contact dermatitis occurred, were statistically analyzed by t.test. Croconazole needed a significantly shorter duration and smaller quantity than sulconazole. This means that the sensitizing ability of croconazole is stronger than that of sulconazole. Since 21 of the 35 imidazole-allergic cases cross-reacted to other imidazole(s), the imidazole derivatives are considered to cross-react frequently.