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Home > Services > Allergy > Allergies We Treat > Poison Ivy, Poison Oak, Poison Sumac

Poison Ivy, Poison Oak, Poison Sumac

Poison ivy, poison oak and poison sumac are plants that can cause allergic reactions in the form of a rash. The reaction is due to the plant's urushiol oil, which is found in the roots, stems, leaves and fruit of the plant. This oil is released if the plant is damaged or bruised.

If not washed, oil from these plants may stay potent for years on clothing, tools, toys and other items, especially in dry conditions. About 50-70 percent of people are allergic to these plants. Virtually everyone becomes sensitized if repeatedly exposed.

poison ivy

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Are You at Risk?

Sensitized people are at risk if they:

  • Work or play in wooded areas during the spring, summer and fall
  • Touch pets or animals that have come in contact with these plants
  • Handle clothes or objects that have come in contact with these plants
  • Are exposed to the smoke of these plants if they are burned


The main symptom of poison oak, ivy or sumac is an intensely itchy, red rash. The rash appears within 24-72 hours of exposure to the oil. The rash often appears streaked and may develop into oozing blisters. 

The skin rash may cause discomfort. It's not serious and usually resolves on its own in 1-2 weeks. Contact a doctor right away if you're highly sensitive or have the following symptoms:

  • Swelling of the face or throat
  • Rash on the genitals
  • Swelling or rash that covers more than one third of your body
  • Rapidly spreading rash
  • Signs of a bacterial infection, such as pain, increased redness or pus

Diagnosis & Treatment

Diagnosis of poison ivy, oak or sumac is based on the presence of a characteristic itchy rash and possible exposure to plants containing urushiol oil.

If Exposed

If you have been exposed to poison ivy, oak or sumac, wash your entire body immediately. You can reduce your chance of getting a rash if you wash thoroughly with soap and water within 10-15 minutes of exposure. Use alcohol and water to wash all clothes, tools and shoes that were in contact with the plant. 

If Rash Develops

If a rash develops, the itching and blisters will usually disappear in 7-14 days without treatment. Treatment to reduce discomfort includes:

  • Cool compresses with water or whole milk
  • Oral antihistamines
  • Over-the-counter medications:
    • Calamine lotion
    • Zinc oxide or baking soda (to dry, oozing blisters)
    • Diluted aluminum acetate solution (Burow's solution)
  • Steroid medications:
    • Cortisone creams to relieve symptoms and may also shorten the duration of the rash
    • Oral corticosteroids (may be prescribed in severe cases)


To prevent a rash from poison ivy, oak or sumac:

  • Learn what the plants look like and avoid all contact with them.
  • Never burn these plants.
  • Wear clothes that cover as much skin as possible when in wooded areas.
  • Bathe pets in soapy water if you think they have come in contact with one of these plants.
  • Wash any clothing or object that may have come in contact with these plants.

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Call us at 434.243.3675.


Content was created using EBSCO’s Health Library. Edits to original content made by Rector and Visitors of the University of Virginia. This information is not a substitute for professional medical advice.

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