Tecnu Extreme Poison Ivy and Oak Scrub gets to the root of your problem by removing the rash-causing plant oils (urushiol) from your skin. It works in only 15 seconds. Simply wet skin, apply Tecnu Extreme to the affected area and rub gently for 15 seconds. If the rash has started, apply Tecnu Extreme to the whole body to remove the oils that are the source of the spreading.