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Symptoms
By Mayo Clinic staff
Signs and symptoms of a poison ivy rash include:
- Redness
- Itching
- Swelling
- Blisters
Often, the rash looks like a straight line because of the way the plant brushes against the 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.
The reaction usually develops 12 to 48 hours after exposure and can last up to eight weeks. The severity of the rash is dependent on the amount of urushiol that gets on your skin.
In severe cases, new areas of rash may break out several days or more after initial exposure. This may seem like the rash is spreading. But it's more likely due to the rate at which your skin absorbed the urushiol.
Your skin must come in direct contact with the plant's oil to be affected. Blister fluid from scratching doesn't spread the rash, but germs under your fingernails can cause a secondary bacterial infection.
When to see a doctor
See your doctor if any of the following occur:
- The reaction is severe or widespread.
- The rash affects sensitive areas of your body, such as your eyes, mouth or genitals.
- Blisters are oozing pus.
- You develop a fever greater than 100 F (37.8 C).
- The rash doesn't get better within a few weeks.
- Contact dermatitis and patch testing. In: Habif TP. Clinical Dermatology. 5th ed. Maryland Heights, Mo.: Mosby, Inc.; 2010. http://www.mdconsult.com/book/player/book.do?method=display&type=bookPage&decorator=header&eid=4-u1.0-B978-0-7234-3541-9..00013-4--s0105&displayedEid=4-u1.0-B978-0-7234-3541-9..00013-4--s0115&uniq=186228941&isbn=978-0-7234-3541-9. Accessed Feb. 28, 2010.
- Contact dermatitis: A practice parameter. Palatine, Ill.: Joint Council of Allergy, Asthma and Immunology. http://www.aaaai.org/professionals/resources/pdf/contact_dermatitis_%202006.pdf. Accessed Feb. 28, 2010.
- Contact dermatitis. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merck.com/mmpe/print/sec10/ch114/ch114c.html. Accessed Feb. 25, 2010.
- Outsmarting poison ivy and other poisonous plants. U.S. Food and Drug Administration. http://www.fda.gov/forconsumers/consumerupdates/ucm049342.htm. Accessed Feb. 28, 2010.
- Poison ivy, oak and sumac. American Academy of Dermatology. http://www.aad.org/public/publications/pamphlets/skin_poison.html. Accessed Feb. 25, 2010.
- Gladman AC. Toxicodendron dermatitis: Poison ivy, oak, and sumac. Wilderness and Environmental Medicine. 2006;17:120.
- Bovine cartilage. Natural Medicines Comprehensive Database. http://www.naturaldatabase.com. Accessed Feb. 28, 2010.
- Poison ivy, oak and sumac. PDRHealth (Physician's Desk Reference). http://www.pdrhealth.com/disease/disease-mono.aspx?contentFileName=BHG01DE21.xml&contentName=Poison+Ivy%2c+Oak%2c+and+Sumac&contentId=120&TypeId=1. Accessed Feb. 28, 2010.
- Mark BJ. Allergic contact dermatitis. Medical Clinics of North America. 2006;90:169.
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