Poison ivy rash

Amanda Bullock / November 21,2022

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Brushing against a poison ivy plant can cause a red, itchy rash with swelling, bumps and blisters. Frequently, the rash takes a linear form (as in the top-left corner of the photo) due to the way the plant sweeps across the skin.

Poison ivy rash is caused by an allergic reaction to an oily resin called urushiol (u-ROO-she-ol). This oil is in the leaves, stems and roots of poison ivy, poison oak and poison sumac.

Wash your skin right away if you come into contact with this oil, unless you know you’re not sensitive to it. Washing off the oil may reduce your chances of getting a poison ivy rash. If you develop a rash, it can be very itchy and last for weeks.

You can treat mild cases of poison ivy rash at home with soothing lotions and cool baths. You may need prescription medication for a rash that’s severe or widespread — especially if it’s on your face or genitals.

Signs and symptoms of a poison ivy rash include:

Often the rash looks like a straight line because of the way the plant brushes against your skin. But if you come into contact with a piece of clothing or pet fur that has urushiol on it, the rash may be more spread out. You can also transfer the oil to other parts of your body with your fingers. The reaction usually develops 12 to 48 hours after exposure and lasts two to three weeks.

The severity of the rash depends on the amount of urushiol that gets on your skin. A section of skin with more urushiol on it may develop a rash sooner.

Your skin must come in direct contact with the plant’s oil to be affected. Blister fluid doesn’t spread the rash.

See your doctor if:

A poison ivy plant typically has three leaflets branching off a single stem. It may grow as a low plant or bush or as a vine. Low-lying poison ivy plants are usually found among groups of weeds and other plants.

Poison ivy leaves vary greatly in their shape, color and texture. Some leaves have smooth edges, while others have a jagged, tooth-like appearance. In the fall, the leaves may turn yellow, orange or red. Poison ivy can produce small, greenish flowers and green or off-white berries.

Poison ivy grows three leaves per stem. It grows as vines or low shrubs in most climates.

The poison sumac plant has smooth-edged leaves and can grow as a bush or tree. Unlike poison ivy and poison oak, it doesn’t grow in a three-leaf-per-stem pattern.

Poison ivy rash is a type of allergic contact dermatitis caused by an oily resin called urushiol. It’s found in the leaves, stems and roots of poison ivy, poison oak and poison sumac. This resin is very sticky, so it easily attaches to your skin, clothing, tools, equipment and pet’s fur. You can get a poison ivy reaction from:

A poison ivy rash itself isn’t contagious — blister fluid doesn’t contain urushiol and won’t spread the rash. And you can’t get poison ivy from another person unless you’ve touched urushiol that’s still on that person or his or her clothing.

Outdoor activities such as the following can put you at higher risk for exposure to poison ivy, poison oak and poison sumac:

If you scratch a poison ivy rash, bacteria under your fingernails may cause the skin to become infected. See your doctor if pus starts oozing from the blisters. Treatment generally includes antibiotics.

To prevent poison ivy rash, follow these tips:

Avoid the plants. Learn how to identify poison ivy, poison oak and poison sumac in all seasons. When hiking or engaging in other activities that might expose you to these plants, try to stay on cleared pathways. If camping, make sure you pitch your tent in an area free of these plants.

Keep pets from running through wooded areas so that urushiol doesn’t accidentally stick to their fur, which you then may touch.

Wash your skin or your pet’s fur. Within 30 minutes after exposure, use soap and water to gently wash off the harmful resin from your skin. Scrub under your fingernails too. This helps prevent a rash. Even washing after an hour or so can help reduce the severity of the rash.

If you think your pet may be contaminated with urushiol, put on some long rubber gloves and give your pet a bath.

Clean contaminated objects. If you think you’ve come into contact with poison ivy, wash your clothing promptly with detergent — ideally in a washing machine. Handle contaminated clothes carefully so that you don’t transfer the urushiol to yourself, furniture, rugs or appliances.

Also wash any other contaminated items — such as outdoor gear, garden tools, jewelry, shoes and even shoelaces — as soon as possible. Urushiol can remain potent for years. So if you put away a contaminated jacket without washing it and take it out a year later, the oil on the jacket may still cause a rash.

 

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