Published onHealth Tip of the Week
The old saying goes: "Leaves of three, let them be." Poison ivy, oak and sumac are three plants that carry the same poison — urushiol, a colorless, odorless oil that causes an itchy, irritating rash in almost everyone who comes in contact with it.
Here’s how you can tell the plants apart:
Poison ivy (A) usually has three broad, tear-shaped leaves. It can grow as a climbing or low-spreading vine that sprawls through grass. It is found everywhere in the United States except Alaska and Hawaii. It often grows along rivers, lake fronts and ocean beaches.
Poison oak (B) has leaves that look like oak leaves and grows as a vine or a shrub. The plant can have three or more leaflets per group. It is most common in the western United States.
Poison sumac (C) has seven to 13 leaflets per stem that are characterized by smooth surfaces and pointed tips. It is most often found in wooded, moist areas of the southern United States.
You can develop a rash by touching poison ivy, oak or sumac, or by touching something that recently came into contact with the oil, like clothing or a pet.
The body's allergic response to the plant toxins may not appear for several days, and severity can change from person to person. The skin will become red and swollen, and then blisters will appear.
After a few days, the blisters will become crusty and start to flake off. They can take one to two weeks to heal.
The rash itself is very itchy and uncomfortable, but it is not contagious. You can’t get the rash by touching the skin of an affected person as long as they have washed off the oil.
After contact with poison ivy, oak or sumac, immediately wash the exposed areas thoroughly with soap and cold water. A bath may spread oil to other parts of your body; showering or hosing off outside is the best way to remove the oil.
It is also very important to wash all clothes and shoes immediately after exposure because oils can remain on them and cause reinfection.
If a rash develops, you can try to relieve itching by:
- Place a warm, wet washcloth on the affected area.
- Take a bath with colloidal oatmeal. Colloidal oatmeal is oatmeal that has been ground to a powder so it will evenly disperse in water. You can buy it from the drug store or make your own by grinding up dry oatmeal in a blender.
- Apply calamine lotion to the affected area.
- Consider a steroid cream (hydrocortisone) if itching persists. Be careful not to get it in your eyes or mouth.
- Consider oral antihistamines, such as diphenhydramine, for unbearable itching, especially if itching interferes with sleep. Consult your pediatrician if you’re unsure whether an oral antihistamine is appropriate for your child.
- Don’t scratch the rash! Scratching can increase damage to the skin and increase the risk of developing a skin infection.
Call your doctor if the rash spreads to the eyes, mouth or genitals. Seek immediate medical attention for severe reactions, especially those resulting in swollen eyes or face or difficulty swallowing or breathing. An oral or intravenous steroid, such as prednisone, and possibly additional medication, such as epinephrine, may be needed to treat severe allergic reactions.
Most allergic reactions will clear up in 14 to 21 days. However, if the symptoms persist or worsen, contact a doctor for further treatment.
- Avoid areas where you know poison ivy, oak and sumac live.
- Wear long sleeves and long pants if exploring wooded areas. Be sure to pull back long hair to prevent oil from spreading to the face.
- If you’re having a bonfire, be sure that these poisonous plants have not made their way into the burn pile. Urushiol, the poison found in these poisonous plants, can be released in the air and can cause breathing problems in addition to skin reactions.
- Show your children pictures of the plants so they learn what to look for. Remind them to ask adults before touching plants because some are harmful.
Visit the Poison Control Center’s website to learn more about poison ivy, oak and sumac, as well as other plants that can irritate the skin. If you have any prevention or treatment questions, call us at (800) 222-1222. The Poision Control Hotline is available 24/7.
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