Poison Ivy Poison ivy is a common cause of an itchy skin rash, especially after outdoor activities such as yard work, gardening, hiking, camping, or playing outside. The rash is caused by contact with an oily plant resin called urushiol, which can be found on poison ivy, poison oak, and poison sumac. For many people, poison ivy can be managed at home. However, some rashes become severe, widespread, infected, or involve sensitive areas of the body. In those cases, medical care