If you buy something through a link on this page, we may earn a small commission. How this works.
If you frequently spend time in nature, you’re probably no stranger to poison ivy, poison oak, and poison sumac. If you’ve been fortunate, you’ve been able to avoid walking into or touching any of these plants. If you’re less fortunate, you haven’t, and you’ve probably ended up with a rash.
The leaves and stems of poison ivy, poison oak, and poison sumac all contain sap with a toxic oil called urushiol. Urushiol irritates the skin of most people exposed to it. It’s also found in different amounts in mango skin and vines, cashew shells, and the urushi (lacquer) tree.
According to the American Academy of Dermatology, 85 percent of people develop a swollen, itchy red rash when they get urushiol on their skin. The rash develops 12 to 72 hours after coming into contact with urushiol.
You don’t have to be outside and have direct contact with poison ivy, poison oak, or poison sumac to be exposed to urushiol.
It can also stick to things like:
- pet fur
- gardening tools
- sports equipment
If you touch these things, you may come into contact with the oil and develop a rash, as the oil absorbs into the skin. Luckily, pets don’t react to the oil.
You can also be exposed to urushiol if poison ivy, poison oak, or poison sumac is being burned. This makes the oil airborne, and you might breathe it in or it could land on your skin.
Here are some images of the rash to help you identify it:
Poison ivy, poison oak, and poison sumac are three separate plants, but they share some characteristics with one another. Their main similarity is that they contain urushiol.
Poison ivy is a vine with leaves growing in clusters of threes. It usually grows close to the ground, but it can also grow on trees or rocks as a vine or small shrub.
The leaves are somewhat pointed. They have an intense green color that can be yellowish or reddish at certain times of the year, and are sometimes shiny with urushiol oil.
Poison ivy grows in most parts of the United States, other than Alaska, Hawaii, and some parts of the West Coast.
Like poison ivy, poison oak has intense green leaves with differing amounts of red color during the year. It also grows in clusters of three.
Poison oak leaves are a bit different than poison ivy leaves. They’re more rounded, less pointy, and have a textured, hair-like surface. Poison oak grows as a low shrub in Eastern and Southern states, but as a long vine or tall clump on the West Coast.
Poison oak is common in the western and southeastern United States.
Poison sumac also grows as a tall shrub or small tree. Unlike poison ivy and poison oak, its leaves grow on stems with groups of 7 to 13 leaves that appear as pairs.
Poison sumac leaves are reddish green. The plant also grows small, whitish-green hanging berries. There’s an almost identical sumac with red, upright berries that’s harmless.
Poison sumac is common in the eastern United States.
Urushiol causes an allergic reaction when a person’s body becomes sensitive to it.
Often, the first time a person is exposed to the oil, they won’t get a rash because of the sensitization that occurs in the body with the first exposure. From the second time on, though, they’ve been sensitized and will develop a rash every time they’re exposed.
Some people never become sensitive and can be exposed to the oil without developing a rash. For others, sensitivity to urushiol can decrease over time. In some cases, children become less sensitive as they grow older.
Sensitivity levels to urushiol vary, and so does the intensity of the rash. If a person has a reaction, it may be mild, moderate, or severe.
- red and itchy skin, which is often an early symptom
- a red rash that develops in streaks or patches where the plant has touched the skin
- a red rash that becomes bumpy with or without small to large wet blisters
In most cases, an allergic reaction from urushiol is mild and lasts around one to three weeks. In severe cases, a rash might last longer.
Inhaling burning poison ivy, poison oak, or poison sumac can cause dangerous rashes and swelling in the nasal passages and airways. If you think you’ve inhaled poison ivy, see a doctor right away to reduce risk of serious complications.
Many people think the rashes caused by poison ivy, poison oak, or poison sumac can spread over the body. They can, but only if the urushiol you come into contact with is spread to and absorbed in other parts of the body.
It can take a long time for the rash to appear on some parts of the body, which can make it seem like the rash is spreading. Once the urushiol is absorbed and causes a rash, it can’t be spread to others.
Also, scratching or touching your rash, or the fluid from your blisters, won’t spread the rash.
Urushiol rashes caused by poison ivy, poison oak, and poison sumac can’t be cured, but the uncomfortable symptoms can be treated.
Although urushiol causes an allergic reaction, immunotherapy in the form of allergy shots isn’t currently available to stop or reduce this effect.
If you think you’ve come into contact with urushiol from poison ivy, poison oak, or poison sumac, you can reduce the severity of your rash and the risk of it spreading by:
- taking off the clothes you’ve been wearing and washing them right away
- washing all exposed areas on your skin with cool water and soap
- using running water to effectively rinse away the urushiol
- washing any tools, equipment, or objects that may have touched urushiol
- bathing any pets that may have touched these plants
If you’ve started to develop a rash and need to treat the symptoms, you may want to try:
- Calamine lotion. Applying this over-the-counter (OTC) anti-itch medication can help soothe your symptoms.
- OTC hydrocortisone topical cream. This product can help ease the itch.
- Prescription corticosteroid medicine. If your reaction is severe or affects sensitive parts of your body — such as the mouth, on or near the eyes, or genitals — see your doctor for a prescription, such as prednisone. Depending on where your rash is, your doctor may recommend the steroid be taken by mouth or be applied directly to the skin. You may also need an injection of corticosteroid. This treatment is meant to help reduce the severity of your reaction, though it can have side effects.
- Antihistamines in pill form. These can also be used to reduce itching.
- Aluminum hydroxide gel, zinc acetate, or zinc oxide. Doctors may recommend these treatments to dry out wet blisters, which often ooze liquid.
- Antibiotic ointment or medication. Some people develop a skin infection with inflammation — such as cellulitis or folliculitis — around their rash, especially if they’ve been itching it. In this case, your doctor will prescribe antibiotics. It’s likely your rash is infected if you have:
- a fever
- feel swelling around the rash
- feel warmth around the rash
- see pus around the rash
Don’t apply antihistamine to your skin, as that can cause further irritation. You should also avoid topical anesthetics, such as benzocaine.
You can use home remedies to relieve urushiol rash symptoms, such as itching, redness, and blistering. These remedies include:
- taking cool showers or applying cool compresses to affected areas
- warm colloidal oatmeal baths
- wearing gloves on your hands to prevent scratching
- taking a baking soda bath
- using soap with water on your rash and rinsing it very well, especially the first time you wash the affected area
- keeping your skin hydrated with a sensitive moisturizing lotion or cream
Or try applying one of these to your rash:
- a paste with three-parts baking soda mixed with one-part water
- aloe vera gel
- cucumber slices
- apple cider vinegar mixed with water
- rubbing alcohol
- witch hazel
- bentonite clay
- chamomile or eucalyptus essential oils
You can prevent a reaction from poison ivy, poison oak, or poison sumac by knowing how urushiol can spread and how to avoid it.
Here are five tips for how to prevent a reaction:
- Know what poison ivy, poison oak, and poison sumac look like, and avoid touching them or walking near them.
- Remove these plants from your yard, and consider hiring a professional to do it. Even if you take precautions by wearing gloves and boots, unless you’re very careful about cleaning your clothes and equipment, you may be exposed to urushiol while working in the yard.
- Fully cover the skin on your ankles, legs, arms, and torso when hiking or spending time in nature to avoid brushing up against these poisonous plants.
- Prevent your pets from spending time in outdoor areas with poison ivy, poison oak, or poison sumac.
- Don’t burn any leaves or woodland, as there’s a chance you may expose yourself to smoke with urushiol in it. Try to avoid inhaling wildfire and other smoke.
Seek immediate medical attention if you have a rash:
- in your throat, mouth, or airways that causes trouble breathing or swallowing — or if you believe you have inhaled smoke from poison ivy, poison oak, or poison sumac
- that covers most of your body
- that’s severe with blisters
- on your face, especially if it’s near your eyes
- on your genitals
- that doesn’t seem to be relieved by home remedies or over-the-counter treatments
See a doctor right away if you have a severe rash or a rash that doesn’t go away after a week or two. A dermatologist will be able to confirm if your rash was caused by a poisonous plant.
Poison ivy, poison oak, and poison sumac may be different plants, but they all contain the same poison: urushiol.
Most people have an allergic reaction in the form of a rash when they’re exposed to urushiol. While a reaction to urushiol can’t be cured, the redness, itching, and blistering it may cause can be treated.
In most cases, the rash will get better on its own within a few weeks. In more severe cases, you may need to see a doctor or seek emergency help.
The more you know about poison ivy, poison oak, and poison sumac, the more easily you can avoid it and prevent an uncomfortable allergic reaction.