Unique dual-action formula: 1. Washes away poison ivy, oak and sumac (Urushiol) from the skin. 2. Relieves itching in 30 seconds. Zanfel is a specially formulated wash for urushiol-induced contact dermatitis. Urushiol is the toxin known to cause the itching and rash associated with poison ivy, oak, sumac, poisonwood, and related plants. The most important step in eliminating the rash is to remove urushiol from the skin. Zanfel works by surrounding urushiol and bonding with it, enabling it to be rinsed away with water. Zanfel offers relief at any stage of the reaction and often with only one wash. Most individuals experience relief from the itching within 30 seconds of application. The rash will begin to subside within hours if the reaction is mild to moderate.