Summertime Rashes: Poison Ivy, Oak, and Sumac
by Jacki Hart, MD
Coming into contact with poison ivy, oak, or sumac can really put a damper on your summer fun. People who are sensitive to these plants can develop a very itchy, red skin rash with bumps and blisters. The oil from the poisonous plants is called urushiol and it sticks to whatever it touches (like skin, clothing, or pet hair) making it a nuisance even after you have left the plant far behind.
The rash is called contact dermatitis—an inflammatory response of the skin when it has come in contact with an allergen (a substance that may start an allergic reaction). In the United States, contact with poison ivy, oak, and sumac are the most common cause of contact dermatitis. All are treatable, but sometimes extreme reactions occur. Call emergency medical services or go to an emergency room if you have trouble breathing or swallowing after exposure to these plants.
Ideally, the best step is to prevent any problems from occurring in the first place. Before you head to the woods or sand dunes this summer, learn about this irritating trio of poisonous plants.
Preventing the Rash
If you think you have been exposed, you have a short window of opportunity to prevent a rash from breaking out. It takes about 10 minutes for urushiol to seep into the skin. As soon as you think that you may have come in contact with 1 of these plants, wash the area well with soap and water.
Anything else that comes in contact with the urushiol has to be washed off to prevent repeat exposure. If you have come in contact or think you have come in contact with these plants wash all clothes in a washing machine. Urushiol can stay on clothes for a long time if unwashed.
If you have a pet that came in contact with the plants, get them into a bath or shower and scrub with pet soap. If you can, make sure you wear disposable gloves so you do not get exposed to the urushiol. It is not likely your pet will be affected, but you can develop a rash if you touch your pet's fur.
You may want to remove the plants that exist near your home. Make sure to wear gloves while doing gardening work. Wash or dispose the gloves when you're done. Do not burn the plants. Smoke from the plants can be inhaled and cause shortness of breath and itchy, watery eyes.
Remember, you have a short window of time to take action. If you miss that window, there are ways to treat that itchy rash.
Treating the Rash
If the rash has set in, the main goals of treatment are to stop the itching, decrease inflammation, and prevent infection.
Itching can make you very uncomfortable, but it may also encourage scratching the area. Constant scratching may lead to an infection through breaks in the skin. An infection will make the healing process take longer. Be on the lookout for infection. Signs of infection include increased redness, tenderness, and/or swelling in the affected area, whitish or yellowish (rather than clear) fluid oozing from the blisters, and an odor. If you suspect infection, call your doctor right away.
Treatment for Mild Reactions
Most of the time, the reaction is mild with the rash covering a small portion of your body. Most likely, you can treat yourself at home with:
Treatment for More Severe Reactions
If you have a more severe outbreak that has blisters, or the rash covers a larger area of your body, see a doctor. You may need additional treatment that includes prescription medication such as:
If you have it now or had it before, take some time to learn about these poisonous plant so you can stay rash-free in the future.
Keep away from any shrubs or vines with leaves of 3. These may be either poison ivy or poison oak. Poison sumac is a leaf of 5. All 3 plants also grow berries in the early fall.
Here are some other ways you can protect yourself:
Know what you are getting into ahead of time if at all possible and take precautions. It will help you keep the poison away and enjoy the outdoors.
American Academy of Dermatology
Family Doctor—American Academy of Family Physicians
Canadian Dermatology Association
The College of Family Physicians of Canada
Contact dermatitis. EBSCO DynaMed website. Available at:
...(Click grey area to select URL)
Updated July 22, 2015. Accessed August 4, 2016.
Outsmarting poison ivy and other poisonous plant. US Federal Drug Administration website. Available at:
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Updated August 4, 2016. Accessed August 4, 2016.
Poison ivy, oak, and sumac. American Academy of Dermatology website. Available at: https://www.aad.org/dermatology-a-to-z/diseases-and-treatments/m---p/poison-ivy. Accessed August 4, 2016.
Usatine RP, Riojas M. Diagnosis and management of contact dermatitis. Am Fam Physician. 2010;82(3):249-255.
Last reviewed August 2016 by Michael Woods, MD
Last Updated: 11/5/2014
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