The term REACTION TO POISON IVY can be summarized as a RASH, which is a four-letter word. A reaction to poison ivy is an allergic reaction that occurs when the skin comes into contact with the plant. It is characterized by an itchy, red RASH that can appear anywhere on the body. The RASH is usually accompanied by swelling and blisters. In some cases, the RASH may also cause pain or burning. Treatment for a reaction to poison ivy typically involves topical creams and antihistamines.