Poison Ivy is a plant that can cause skin irritation in many people. It contains an oil called urushiol, which triggers allergic reactions upon contact. The plant typically grows as a vine or shrub and is commonly found in wooded areas, gardens, and along trails in North America. Its leaves are usually grouped in threes, which is a helpful way to identify it. When someone comes into contact with Poison Ivy, they may develop a red, itchy rash that can blister. The rash usually appears within 12 to 72 hours after exposure and can last for several weeks. To treat the rash, over-the-counter creams and antihistamines can help relieve symptoms, while severe cases may require medical attention.