What's an Itch?
Dealing With Poison Ivy’s Rash
Depending on how sensitive you are and how much poison ivy gets on your skin, an itchy red rash will start to develop anywhere from 24 to 72 hours after contact. As your immune system battles with urushiol, the area may become inflamed and very itchy. The rash often turns into oozing blisters.
It may seem almost impossible not to scratch the rash, but Pamela Scheinman, MD, director of the Contact Dermatitis and Occupational Dermatology Unit at Tufts Medical Center, advises against it. Vigorous scratching can break the skin. “If the skin barrier is not intact, the risk of bacterial infection goes up,” Scheinman says.
Usually, poison ivy rash is at its worst one week after exposure. Unless you have a severe case of poison ivy, the rash should go away within one to two weeks.
To relieve itching, try calamine lotion, an over-the-counter hydrocortisone cream, or antihistamine.
How Poison Ivy Does and Does Not Spread
The idea that poison ivy rash spreads from one part of your body to another is a common but understandable myth.
People often think it has spread because different areas of skin can break out at different times after a single exposure. But the rash only breaks out where urushiol has had direct contact with the skin -- touching the rash or blisters won’t spread it. Your skin may absorb the oil at different rates, Scheinman tells WebMD. Areas where your skin is the thinnest may break out first: wrists, ankles, neck, and face.
By the time the poison ivy rash appears, the urushiol that triggered it has probably been washed off. But the oil does have staying power on clothes, shoes, and other items, however. Scheinman has seen people who were exposed through touching garden tools or sporting equipment with traces of urushiol on them.