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Poison ivy - oak - sumac rash

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Poison oak rash on the arm
Poison oak rash on the arm
Poison ivy on the knee
Poison ivy on the knee
Poison ivy on the leg
Poison ivy on the leg

Definition    Return to top

Poison ivy, oak, and sumac are plants that commonly cause an allergic skin reaction. The result is typically an itching, red rash with bumps or blisters.

Considerations    Return to top

Poison ivy is one of the most frequent causes of skin rash among children and adults who spend time outdoors. The plant can be found throughout the United States, except in the Southwest, Alaska, and Hawaii. It has three shiny green leaves and a red stem. Poison ivy typically grows in the form of a vine, often along riverbanks.

Poison oak is primarily found on the West Coast. It grows in the form of a shrub and has three leaves similar to poison ivy.

Poison sumac grows abundantly along the Mississippi River. It grows as a woody shrub. Each stem contains 7-13 leaves arranged in pairs.

Causes    Return to top

The rash is caused by skin contact with the oily sap (or resin) of these plants. Smoke from burning these plants can cause the same reaction. The oily resin usually enters the skin rapidly, and is seldom transferred from person to person. The rash is NOT caused by the fluid from the blisters. Thus, once the person has washed the oil off the skin, the rash is usually not contagious.

Keep in mind that the resin may last for long periods on contaminated, clothing, pets, tools, shoes, and other surfaces. These contaminated items can cause future rashes long after the initial exposure.

Symptoms    Return to top

The rash usually appears within a couple of days after contact with the plant's oils. The worst stage is often from days 4 to 7. The rash may last for 1 to 3 weeks.

First Aid    Return to top

DO NOT    Return to top

When to Contact a Medical Professional    Return to top

Call 911 or go to an emergency room if:

Call your provider if:

Prevention    Return to top

Other steps include:

References    Return to top

Auerbach PS. Wilderness Medicine. 4th Ed. St. Louis, MO: Mosby:2001;194-195.

Marx JA, Hockberger RS, Walls RM, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 5th Ed. St. Louis, MO: Mosby; 2002:1647-1648,2200.

Habif, TP. Clinical Dermatology. 4th Ed. St. Louis, MO: Mosby;2004:25,85-89,402.

Update Date: 2/27/2008

Updated by: Stephen C. Acosta, MD, Department of Emergency Medicine, Portland VA Medical Center, Portland, OR. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 1997-2008, A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.