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Poison Ivy

What Is Poison Ivy?

Leaves of three, let them be! You've probably heard that little rhyme about poison ivy. But did you know that the plants poison ivy, poison oak, and poison sumac all contain the same rash-causing substance? It's called urushiol (pronounced: yoo-ROO-shee-ol), a colorless, odorless oil (called resin) found in their leaves.

What Are the Signs & Symptoms of Poison Ivy?

Urushiol is considered an allergen because it causes an allergic reaction. The poison ivy reaction takes the form of a rash, itching, and sometimes swelling. Not everyone gets a reaction to urushiol, but most people do. This reaction can start within hours of coming into contact with urushiol or up to 5 days later.

Typically, the skin becomes red, itchy, and swollen and blisters will appear. After a few days, the blisters may become crusty and start to flake off. The rash that people get from poison ivy can take 2 to 3 weeks to heal.

When Should I Call the Doctor?

It's a good idea to call your doctor if you have any kind of rash, especially if you have a fever too. If your rash is from poison ivy or a similar plant, the doctor may tell you to take cool showers and to use a soothing lotion, such as calamine lotion.

In more severe cases, doctors may prescribe pills or creams that contain antihistamines or steroids (not the same type of steroids that bodybuilders use!) to decrease itching and redness.

Is Poison Ivy Contagious?

The poison ivy rash itself isn't contagious. Fluid from a blister can't spread the rash. But it is possible to get a rash from poison ivy without touching a plant. Urushiol can transfer from one person to another from their skin or clothing. Urushiol can even travel through the air if someone burns the plants to clear brush.

How Can I Protect Myself From Poison Ivy?

Poison ivy can grow anywhere — from the woods to your own backyard. And it can be hard to see: The leaves of poison plants blend right in with other plants and brush. Plus, there are several types of poison ivy, and each one can look different depending on the time of year.

The leaves of poison ivy plants release urushiol when they're bumped, torn, or brushed against. When the resin is released, the leaves may look shiny or have black spots. Then, it can get on a person's skin.

Here are some tips to help you avoid getting a rash from poison ivy:

  • Learn to identify poison ivy, oak, and sumac, so you can steer clear of them. (Be especially careful of plants if the leaves look shiny.)
  • Avoid areas where you know there's poison ivy.
  • Wear long sleeves and long pants when you're in areas where poison ivy might grow.
  • If your dog has been out exploring the woods, give him a shower to wash off any urushiol oil that may be on his coat.

If you come into contact with urushiol oil, wash it off your skin right away by taking a shower and using lots of soap. Don't take a bath — the oil can get in the bath water and spread to other areas of your body.

Reviewed by: Yamini Durani, MD
Date Reviewed: Apr 1, 2023

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