Allergic contact dermatitis to cinchocaine.

A case of allergic contact dermatitis to cinchocaine is presented to highlight the confusion regarding the classification of, and cross-reactivity between, topical anaesthetic agents and the inadequacy of the use of benzocaine as a single screening agent for topical anaesthetic contact allergy. Our patient presented with a 10-day history of acute perianal dermatitis. Allergic contact dermatitis to Proctosedyl ointment, which was applied for 3 weeks prior, was suspected. On patch testing, he reacted to cinchocaine, a constituent of Proctosedyl ointment, and to the actual product, but had no reaction to benzocaine or lignocaine.