How to Treat a Rash from Poison Ivy, Oak, and Sumac

Published: August 10, 2023
Barbara Young
By Barbara Young, PharmD

Do you have red itchy bumps on your skin 24-72 hours after working in your garden or going camping in the woods?  If so, you may be one of the millions of people in the US that has a reaction to poison ivy, oak, or sumac each year.

What causes the rash?
The rash is caused by contact with urushiol, a substance contained in the sap of these plants. About 50 -75% of people are allergic to this substance, which is released from the stems, roots, leaves when the plant is damaged or bruised.

Can I treat the rash at home?
If you have a mild rash on a small amount of skin and feel sure that it is due to contact with one of these plants, it can be treated at home.

First you should wash your skin with warm soapy water. Also wash the clothing that you wore when you were exposed to the plant and any other items that came into contact with the plant/sap. Be sure to wear gloves when handling these items or if you need to bathe pets that may have had contact with these plants.

Do not scratch the rash or open the blisters on the skin. This can lead to infection. To relieve the itching, you can:

  • take short baths in lukewarm water.
  • use calamine lotion or hydrocortisone cream as directed on the product’s label.
  • apply a clean wet washcloth to the area.
  • take an antihistamine such as Benadryl® by mouth to make it easier to sleep. DO not apply an antihistamine to the skin as it can make the rash and itching worse.

When do I need to see a doctor?
If you have any of the following, immediately get medical care:

  • difficulty breathing or swallowing,
  • a rash around one or both eyes, your mouth, or on your genitals,
  • swelling on your face, especially if your eye(s) swell shut,
  • itching that worsens or is so bad you can’t sleep,
  • rashes on most of your body, or
  • a fever.

You may need to see a doctor if you are not certain the rash is caused by poison ivy, oak, or sumac.  You should also contact your health care provider if your rash does not improve in 7-10 days, gets worse, or appears to be infected.

One of the best ways to prevent getting poison ivy, oak, or sumac is to be able to identify the plants and avoid contact with them. If you do get a rash from contact with these plants, ask your pharmacist about treatments that can help to provide relief from the symptoms.

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