Over the years, changes have had to be made in the list of topical drugs most frequently responsible for allergic contact dermatitis. The 4 most common sensitizers in Italy in the past have been penicillin, sulfonamide, promethazine and neomycin. Now the list is headed by neomycin, benzocaine and ethylenediamine. Antihistamines and parabens are less frequently observed as sensitizers. The increasing topical use of new drugs and additives, as well as older sensitizers, produces reactions to other substances, such as non-steroidal anti-inflammatory agents, some antimycotic drugs, propylene glycol and benzoyl peroxide.