American plants whose leaves can cause a painful rash if touched.
A type of contact dermatitis caused by skin exposure to an oily substance in the sap from the poison ivy plant. Poison ivy is characterized by red, intensely itchy patches of skin that soon begin to swell and blister. A rash can also develop if a person touches clothing, shoes, or a pet that has been exposed to poison ivy.
A climbing vine, Toxicodendron radicans, which on contact may produce a severe form of pruritic dermatitis. Rhus species contain urushiol, an extremely irritating oily resin, and pentadecylcatechol, a common allergen, which stimulates a type IV hypersensitivity reaction. First contact produces sensitization; later contacts cause severe blistering, eczema, and itching.