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Adult Symptoms > Skin - Localized Symptoms > Poison Ivy - Oak Or Sumac
Poison Ivy - Oak or Sumac


  • Localized red rash with small blisters following poison ivy, oak or sumac exposure
  • Rash is very itchy
  • Located on exposed body surfaces (such as the hands) or areas touched by the hands (e.g., the face or genitals)

General Information

  • Poison Ivy, Poison Sumac, and Poison Oak are three plants that can cause an itchy red rash in sensitive individuals. The oil contained in the plant leaves irritates the skin. The redness and blistering from the rash is often arranged in streaks or lines, because the leaves brush across the body in a line as an individual walks past.
  • Onset: ¬†Following a first-time exposure, the onset time for the rash is 1 to 2 weeks. For recurrences, the onset is 8 to 48 hours after the individual was in a forest or field.

Preventing the Rash!

  • Avoid Exposure: Avoid exposure to these plants, especially if you have had a bad reaction in the past.
  • Wash skin: If you are exposed, remove the irritating plant oil from your skin as soon as possible. Wash the exposed part of your body with soap and water within 30 minutes. Wash your clothes in warm soapy water.
  • IvyBlock: An over the counter cream that you put on your skin before walking in the woods. It coats the skin and acts as a barrier to the irritating oil of the poison ivy/oak/sumac plants and prevents the rash from occurring. More information is available at http://www.ivyblock.com.


Call Your Doctor Now (night or day) If

  • You feel weak or very sick
  • Difficulty breathing or severe coughing following exposure to burning weeds
  • Fever and bright red area or streak (from open poison ivy sores)
  • Increasing redness around poison ivy and larger than 2 inches (5 cm)

Call Your Doctor Within 24 Hours (between 9 am and 4 pm) If

  • You think you need to be seen
  • Swelling is severe (e.g., the eyes are swollen shut)
  • Severe poison ivy reaction in the past
  • Severe itching interferes with normal activities (e.g., work or school) or prevents sleep
  • Rash involves more than one fourth of the body
  • Face, eyes, lips or genitals are involved
  • Big blisters or oozing sores
  • Taking oral steroids more than 24 hours and rash becoming worse

Call Your Doctor During Weekday Office Hours If

  • You have other questions or concerns
  • Rash lasts longer than 3 weeks

Self Care at Home If

  • Mild poison ivy, oak or sumac rash and you don't think you need to be seen


  1. Hydrocortisone Cream for Itching:
    • Apply 1% hydrocortisone cream 4 times a day to reduce itching. Use it for 5 days.
    • Keep the cream in the refrigerator (Reason: it feels better if applied cold)
    • Available over-the-counter in U.S. as 0.5% and 1% cream.
    • Available over-the-counter in Canada as 0.5% cream.
  2. Local Cold: Soak the involved area in cool water for 20 minutes or massage it with an ice cube as often as necessary to reduce itching and oozing.
  3. Oral Antihistamine Medication for Itching: Take an antihistamine by mouth to reduce the itching. Diphenhydramine (Benadryl) is available over-the-counter. Adult dose is 25-50 mg. Take it up to 4 times a day.
    • Do not take antihistamine medications if you have prostate enlargement.
    • Antihistamines may cause sleepiness. Do not drink, drive or operate dangerous machinery while taking antihistamines.
    • An over-the-counter antihistamine that causes less sleepiness is loratadine (e.g., Alavert or Claritin).
    • Read the package instructions thoroughly on all medications that you take.
  4. Avoid Scratching: Cut your fingernails short and try not to scratch so as to prevent a secondary infection from bacteria.
  5. New Blisters Appear: If new blisters occur several days after the first ones, you probably have had ongoing contact with the irritating plant oil. To prevent recurrences: bathe all dogs and wash all clothes and shoes that were with you on the day of exposure.
  6. Contagiousness: Poison ivy or oak is not contagious to others.
  7. Expected Course: Usually lasts 2 weeks. Treatment reduces the severity of the symptoms, not how long they last.
  8. Call Your Doctor If:
    • Rash lasts longer than 3 weeks
    • It looks infected
    • You become worse

And remember, contact your doctor if you develop any of the "Call Your Doctor" symptoms.

Disclaimer: This information is not intended be a substitute for professional medical advice. It is provided for educational purposes only. You assume full responsibility for how you choose to use this information.

Author and Senior Reviewer: David A. Thompson, M.D.

Last Reviewed: 9/15/2011

Last Revised: 12/20/2009

Content Set: Adult HouseCalls Symptom Checker

Copyright 2000-2012. Self Care Decisions LLC; LMS, Inc.

Additional Resources:

 How to use the Adult Health Topics pages
 When to call the doctor
 Reviewers of Clinical Content

Disclaimer: The information contained in these topics is not intended nor implied to be a substitute for professional medical advice, it is provided for educational purposes only. You assume full responsibility for how you choose to use this information.

Always seek the advice of your physician or other qualified healthcare provider before starting any new treatment or discontinuing an existing treatment. Talk with your healthcare provider about any questions you may have regarding a medical condition. Nothing contained in these topics is intended to be for medical diagnosis or treatment.

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