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Poison ivy, oak, and sumac are plants that can cause a red, itchy rash called
allergic contact dermatitis. It is the most common skin problem caused by
contact with plants.
rash is caused by contact with a sticky oil called urushiol (say "yoo-ROO-shee-all") found in poison ivy, oak, or
sumac. You can get the rash from:
The rash is only spread through the oil. You
can't catch a rash from someone else by touching the
The rash is an
allergic reaction to the oil. You become allergic to it through contact. After you have come in contact with these plants, your immune system may start to react to the oil as though it's a harmful substance.
symptoms of the rash are:
Some people are very allergic to the oil. In these people, even a little bit of the oil may cause serious symptoms that need medical attention right away, such as:
The rash usually takes more than
a week to show up the first time you have a reaction to the oil. It
develops in a day or two on later contacts. The rash
may form in new areas over several days, but you will only get a rash where the oil touched your skin.
The rash usually lasts about 10 days
to 3 weeks. But it may last
up to 6 weeks in more severe cases.
A doctor can usually diagnose the rash by looking at it and asking questions about:
If you get a mild rash, you can take care of it at home.
Do not use the following medicines. They can cause allergy
problems of their own:
See your doctor if the rash covers a large area of your body or your symptoms are severe. A doctor may prescribe a corticosteroid cream to help clear up the rash. A severe rash may be treated with corticosteroid pills or shots.
If you think you have touched any of these plants:
The best way to prevent future rashes is to learn to identify
these plants and avoid them.
When you can't avoid contact with the plants:
Experts say not to burn plants like poison ivy, oak, or sumac. When these plants burn, urushiol attaches to smoke particles. Exposure to the smoke can cause a rash on your skin. Breathing in the smoke can also hurt your lungs.
Learning about poison ivy, oak, and sumac:
Living with poison ivy, oak, and sumac rash:
Other Works Consulted
Hall JC (2010). Dermatologic allergy. In JC Hall, ed., Sauer's Manual of Skin Diseases, 10th ed., pp. 78–104. Philadelphia: Lippincott Williams and Wilkins.
Shofner JD, Kimball AB (2012). Plant-induced dermatitis. In PS Auerbach, ed., Wilderness Medicine, 6th ed., pp. 1232–1251. Philadelphia: Mosby.
August 19, 2013
William H. Blahd, Jr., MD, FACEP - Emergency Medicine
& H. Michael O'Connor, MD - Emergency Medicine
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