After ivy Poison Ivy Cleanser may be used after contact with poison ivy, oak or sumac or after symptoms begin. It is gentle, exfoliating cleanser. After Ivy is Hypoallergenic, Dermatologist and Pediatrician tested. it works be helping remove urushiol from the skin. Urushiol is the toxic, oily substance in these plants that can trigger allergic reactions when exposed to the skin. One washing per exposed or affected area is typically sufficient for mild to moderate cases. For severe cases, contact your physician.