toxicodendron dermatitis (MONDO_0006616) is an allergic contact dermatitis caused by exposure to plants of the genus Toxicodendron (formerly Rhus). These include poison ivy, poison oak, and poison sumac, all plants that contain the substance urushiol, a potent skin sensitizing agent. (From Dorland, 27th ed). Also known as: Rhus dermatitis, contact dermatitis due to genus Toxicodendron.