Allergic contact dermatitis from resacetophenone (2',4'-dihydroxyacetophenone; CAS no. 89-84-9) in an antifungal nail preparation.

We report the first two cases of allergic contact dermatitis from resacetophenone in a nail antifungal preparation. Patch tests gave positive reactions to resacetophenone (0.1% and 1% pet.). No cross-reactions with resorcinol or phenylethyl resorcinol were found. Patch testing with individual ingredients is paramount to diagnose new allergens.