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Poison Ivy Dermatitis

What is it?

Poison ivy dermatitis is a skin inflammation that occurs when the skin touches the oil contained in the poison ivy plant, which triggers an allergic reaction. Poison ivy is a weed found in just about every state except Alaska and Hawaii.

Who gets it?

People who are sensitive to the oil in the poison ivy plant get this type of dermatitis. Over 50% of the population has this sensitivity, which can run in families.

What causes it?

Poison ivy dermatitis is a type of allergic contact dermatitis (ACD). ACD occurs when a substance called an allergen triggers the body’s immune response. In this case the allergen is the poison ivy plant oil, called urushiol, which is quickly absorbed by the skin. The immune system produces antibodies and other disease fighting cells in response to the allergen. The antibodies release chemicals that actually injure the surrounding cells and cause the physical symptoms of an allergic reaction. Poison ivy oils can be carried on anything that rubs against the plant, such as clothing and pet fur, and still cause a reaction when touched. If the plant is burned, the oils can be carried in the smoke and cause a reaction in those who are sensitive. Poison ivy dermatitis is not contagious and is not spread from the fluid from the blisters.

What are the symptoms?

The symptoms of poison ivy dermatitis usually appear within one to two days of contact with the plant oils. They begin with intense itching and a rash that progresses to swelling and blistering. In severe cases, open sores can result in bacterial skin infections. The inflammation is confined to the area that had contact with the plant, often the hands or face, and can occur on any part of the body. In most cases, the blisters dry up and heal within two to three weeks.

How is it diagnosed?

Poison ivy dermatitis is diagnosed according to a pattern of symptoms. Your doctor will take your medical history and ask you questions about your activities and the types of substances you had contact with right before the symptoms appeared.

What is the treatment?

If you know you have had contact with poison ivy, you can prevent or minimize symptoms by washing the area thoroughly with soap and water. To treat poison ivy dermatitis, your doctor can recommend ointments or lotions to relieve itching and irritation until the symptoms go away. If you have severe swelling and/or itching, your doctor may prescribe oral or topical corticosteroids or oral antihistamines. Antibiotics are prescribed for bacterial skin infections. You can relieve itching by bathing the area with cool water or soaking in an oatmeal preparation.

Self-care tips

You can prevent poison ivy dermatitis by knowing what the poison ivy plant looks like and avoiding contact with it. It’s always a good idea to wear protective clothing before walking in areas where there is overgrowth or a likelihood of poisonous plants. People who are extremely sensitive to poison ivy can use protective creams before entering areas where they are likely to contact the plant.


This information has been designed as a comprehensive and quick reference guide written by our health care reviewers.  The health information written by our authors is intended to be a supplement to the care provided by your physician.  It is not intended nor implied to be a substitute for professional medical advice. 

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This page was last updated on October 31, 2006
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