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Causes
By Mayo Clinic staff
Poison ivy rash is caused by an oily resin called urushiol — found in the leaves, stems and roots of poison ivy, poison oak and poison sumac. Urushiol is very sticky, so it easily attaches to your skin, clothing, tools, equipment or pet's fur. You can get a poison ivy reaction from:
- Direct touch. If you directly touch the leaves, stem, roots or berries of the plant, you may have a reaction.
- Touching contaminated objects. If you walk through some poison ivy and then later touch your shoes, you may get some urushiol on your hands, which you may then transfer to your face by touching or rubbing. If the contaminated object isn't cleaned, the urushiol on it can still cause a skin reaction years later.
- Inhaling smoke from the burning plants. Even the smoke from burning poison ivy, poison oak and poison sumac contains the oil and can irritate or harm your nasal passages or lungs.
A poison ivy rash itself isn't contagious. Blister fluid doesn't contain urushiol and won't spread the rash. In addition, you can't get poison ivy from another person unless you've had contact with urushiol that's still on that person or on his or her clothing.
References
- Auerbach PS. Wilderness Medicine. 6th ed. Philadelphia, Pa. Elsevier Mosby: 2011. http://www.mdconsult.com/books/page.do?eid=4-u1.0-B978-1-4377-1678-8..00063-5--s0055&isbn=978-1-4377-1678-8&uniqId=343851441-3#4-u1.0-B978-1-4377-1678-8..00063-5--s0055. Accessed July 3, 2012.
- Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 5th ed. Edinburgh, U.K.; New York, N.Y.: Mosby Elsevier; 2010. http://www.mdconsult.com/books/about.do?about=true&eid=4-u1.0-B978-0-7234-3541-9..X0001-6--TOP&isbn=978-0-7234-3541-9&uniqId=230100505-57. Accessed July 3, 2012.
- Prok L, et al. Poison ivy (Toxicodendron) dermatitis. http://www.uptodate.com/index. Accessed July 3, 2012.
- Poisonous plants. National Institute for Occupational Safety and Health. Centers for Disease Control and Prevention. http://www.cdc.gov/niosh/topics/plants. Accessed July 3, 2012.
- Outsmarting poison ivy and other poisonous plants. U.S. Food and Drug Administration. http://www.fda.gov/forconsumers/consumerupdates/ucm049342.htm. Accessed July 3, 2012.
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