Canesten Dermatological Spray Canesten Dermatological Spray is a cooling spray that is applied directly to the skin to treat fungal skin infections such as ringworm, athlete's foot, jock itch & fungal sweat rash & is particularly useful for infections covering large, hairy or hard to reach areas. The active ingredient in Canesten Dermatological Spray is clotrimazole, an antifungal agent which fights the cause of fungal skin infections.