Contact urticaria and allergic contact dermatitis to benzocaine gel

A 39-year-ole man developed edema and vesiculation of the oral mucosa following the application of benzocaine (Hurricaine) gel. Open testing demonstrated an immediate urticarial reaction. Closed patch tests were positive after 48 hours. The contact dermatitis was consistent with a delayed-type hypersensitivity. It appears, however, that a nonimmunologic mechanism caused the contact urticaria since passive transfer was negative.