Contact allergy to imidazole antimycotics

Between 1977 and 1986, 9 patients with contact allergy to the active ingredient of imidazole antimycotics were found at the Department of Dermatology, University of Heidelberg. The number of positive reactions decreased in the following order: miconazole (6), clotrimazole (3), econazole (3), isconazole (3), and oxiconazole (1). When 5 patients were tested with a series of imidazoles in different concentrations and vehicles (petrolatum, ethyl methyl ketone, ethanol), petrolatum turned out to be the least effective one. The active ingredient at 1% in ethanol seems to be the most suitable choice for routine patch testing. Bifonazole may be the therapeutic alternative for patients sensitive to miconazole or clotrimazole, since no cross reactivity was observed.