Contact allergy to tioconazole

In 15 months, we detected allergic patch test reactions to tioconazole in 14 patients. 9 of the 14 patients were allergic to additional imidazole derivatives used as antifungal agents. The positive patch test reactions to tioconazole may have been caused either by simultaneous sensitization or more probably by cross-reactivity between the various commercially used imidazole derivatives with a similar chemical structure. The abundant use of tioconazole in concentrated (up to 28%) topical formulations in Finland could be the major cause of the apparent increase in allergic reactions.