Urushiol /ʊˈruːʃi.ɒl/ is an oily organic allergen found in plants of the family Anacardiaceae, especially Toxicodendron spp. (e.g., poison oak, poison ivy, poison sumac) and also in mangos.[1][2][3][4][5] In sensitive individuals, urushiol can cause an allergic skin rash on contact,[6] known as urushiol-induced contact dermatitis. The name comes from the Japanese word for the tree Toxicodendron vernicifluum (漆 urushi?).[7]
The oxidation and polymerization of urushiol in the tree's sap in the presence of moisture allows it to form a hard lacquer, which is used to produce traditional Chinese, Korean and Japanese lacquerware.