Cross-reactions may occur between mango allergens and urushiol. "Toxicodendron diversilobum" leaves and twigs have a surface oil, urushiol, which causes an allergic reaction. The rash is caused by urushiol, a clear liquid compound in the plant's sap. Approximately 25 percent of the population will have a strong allergic response to urushiol. The name urushiol is derived from the Japanese word for the lacquer tree, . People who are sensitive to urushiol can also experience a similar rash from mangoes. It effectively helps to break up the oil urushiol that causes the rash. Hydrocortisone itself does not react with urushiol in any way. In rare cases, urushiol reactions may require hospitalization. Neither native animals nor horses, livestock, or dogs demonstrate reactions to urushiol. There are a number of forms of urushiol. Within the United States, urushiol containing plants are distributed throughout. People vary greatly in their sensitivity to urushiol. Over 350,000 people are affected by urushiol annually in the United States.