Urushiol

Urushiol /ʊˈruːʃi.ɒl/ is an oily organic allergen found in plants of the family Anacardiaceae, especially Toxicodendron spp. (e.g., poison oak, Lacquer Tree, poison ivy, poison sumac) and also in mangos.

In sensitive individuals, urushiol can cause an allergic skin rash on contact, known as urushiol-induced contact dermatitis.