why does poison ivy itch
The poison ivy rash often looks like red lines, and sometimes it forms blisters. The culprit behind the rash is a chemical in the sap of poison ivy plants called urushiol (oo-roo-shee-ohl). Its name comes from the Japanese word urushi, meaning lacquer.Urushiol is the same substance that triggers an allergic reaction when people touch poison oak and poison sumac plants.he poison ivy rash often looks like red lines, and sometimes it forms blisters. The culprit behind the rash is a chemical in the sap of poison ivy plants called urushiol (oo-roo-shee-ohl). Its name comes from the Japanese word urushi, meaning lacquer.