Just thinking about poison ivy can make you itch. Blistering rashes on your arms and ankles, oozing bumps between your fingers and eyelid-swelling exposures are all-too-familiar summer hazards. Poison ivy lurks for kids, campers, hikers, gardeners and anyone else who ventures too close. Identifying and avoiding poison ivy — and its cousins, poison oak and poison sumac — is ideal.
If you come into contact with these toxic plants, here’s what you need to know.
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What Does Poison Ivy Look Like?
Three leaves is the consistent clue to poison ivy, says Diane Brown, an educator in consumer horticulture and commercial fruit with the Michigan State University Extension program. Otherwise, she says, poison ivy can be a bit of a “chameleon.”
Poison ivy leaves don’t all look the same. Some poison ivy leaves have “toothed” or wavy edges while others have smooth edges. Leaflets might be dull or shiny; hairy or hairless. Leaves start out green as they grow and turn reddish purple in fall. During the spring, poison ivy flowers and produces white berries that last into the winter.
The toxic ingredient of poison ivy is an oily resin called urushiol. You get poison ivy rash by coming into contact with this oil.
Poison ivy is the most common of the three, Brown says, and it grows throughout many parts of the U.S. Poison oak is more often found out West, she says, while poison sumac tends to grow near swampy areas.
[SEE: Best Anti-Itch Products: Poison Ivy and Poison Oak Treatments]
Symptoms of a Poison Ivy Rash
An itchy rash with redness and swelling is the main sign of an outbreak. Bumps often turn into poison ivy blisters. The rash may form an obvious pattern — like a circle around your ankle in the gap between your pants and socks. Other times the rash is diffuse, spreading at random.
— Redness
— Itching
— Swelling
— Blisters
— In some cases, difficulty breathing, if you’ve inhaled smoke from burning poison ivy
People contract a poison ivy rash when their skin comes into contact with urushiol, an oily resin present in the leaves, stems and roots of the ominously named plant. The substance is absorbed quickly into the skin.
Symptoms of poison ivy exposure typically occur within four to 96 hours after contact. A poison ivy rash progresses through several stages, including initial itching, redness, blister formation, fluid leakage and finally, crusting over as it heals. The entire process can take up to 3 to 4 weeks.
Identifying a rash as being caused by poison ivy can be straightforward, if you know what to look for. There are no laboratory studies — like a blood test — to practically diagnose a poison ivy rash. A doctor identifies the rash by looking at it.
Many people are unaware when they come into contact with poison ivy, which is most prevalent east of the Rockies. If poison ivy touches your skin, the odds are good you’ll get a rash.
Are some people more sensitive to poison ivy?
The medical term for poison ivy rash is allergic contact dermatitis. About 85% of people who come into contact with the oil develop a rash, according to the American Academy of Dermatology. Anybody can develop sensitivity to poison ivy, and that sensitivity can change over time.
“Patients who are highly sensitive or have a hypersensitivity reaction to poison ivy can develop severe blistering or even anaphylaxis,” says Dr. Seemal Desai, the medical director of Innovative Dermatology in Plano, Texas. Anaphylaxis is a severe, life-threatening allergic reaction.
“I have seen cases of severe poison ivy that persist several weeks,” Desai adds. That’s because oils in poison ivy stimulate the immune system, he says, causing it to go haywire.
Is poison ivy contagious?
A common misconception about poison ivy rash is that it’s contagious, says Dr. Susan Massick, a dermatologist at the Ohio State University Wexner Medical Center in Columbus, Ohio. “That is not correct,” she says. The rash and blisters caused by poison ivy aren’t contagious. Blisters do not contain poison ivy oil. Instead, blisters contain serous fluid formed by the body. The transparent, clear-colored or yellow fluid does not spread poison ivy.
It’s actually the oil from the poison ivy that causes the rash. So, coming into contact with clothing — yours or someone else’s — directly exposed to poison ivy oil can spread it.
The important part is to get the oils removed from the skin as soon as possible. Oils tend to sit on the skin’s surface.
“You can also get it from pets, pruning tools, power cords dragged through poison ivy and so on,” Brown says. After gardening or any possible poison-ivy exposure, launder your clothes with strong detergent. Similarly, hose off garden tools, golf clubs and other outdoor objects as needed.
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What to Do If You Come in Contact With Poison Ivy or Poison Oak
If you think you’ve come into contact with poison ivy, you can take these steps, says Dr. David M. Cutler, a family medicine physician at Providence Saint John’s Health Center in Santa Monica, California:
— Quickly wash off the resin with soap and water to try to prevent an allergic reaction.
— Launder clothes and shoes which may have come into contact with poison ivy.
— Once the rash begins, a number of over-the-counter products, like topical corticosteroid cream, can be helpful in treating your symptoms.
— If the area becomes infected, see your health care provider, who can prescribe antibiotics.
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How Long Does Poison Ivy Last?
Poison ivy lasts about one to three weeks. Rashes are usually self-limiting — they heal on their own. However, rashes can become infected, especially when scratching opens the skin. If blisters are oozing pus, if you develop a fever or the rash refuses to heal, those are signs of infection.
Remedies for Poison Ivy
Oatmeal baths, also called colloidal oatmeal, can ease the itching. Use lukewarm bath water and add the oatmeal preparation. You can buy oatmeal bath products from brands like Aveeno, or make your own using uncooked whole oats and a blender. Soak for a few minutes, but not too long, because the skin can actually get drier and itchier.
Short, cool showers may help, as well as cool compresses on the skin.
OTC medicines for poison ivy include calamine lotion and topical hydrocortisone creams.
If the rash is severe or these products don’t provide relief, your doctor may need to prescribe stronger medication.
“Systemic steroids are often needed to calm down acute cases of poison ivy,” says Desai, who advises seeking out a board-certified dermatologist if possible to avoid long-term poison-ivy consequences.
FAQs About Poison Ivy
Can dogs get poison ivy?
Dogs and other pets are not physically affected by poison ivy. However, by going outdoors and getting the oil on their fur, they can spread poison ivy to their owners and other people. Thoroughly rinse your exposed pet’s fur, leash and collar.
Is it OK to scratch poison ivy?
It’s so tempting to scratch — but don’t.
“I encourage patients to do their best possible not to scratch,” Desai says. “We know that chronic scratching can leave open wounds, and those wounds can sometimes get infected with bacteria or other organisms that live on the surface of the skin or in the environment.”
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How to Identify and Treat a Poison Ivy or Poison Oak Rash originally appeared on usnews.com
Update 04/22/25: This story was published at an earlier date and has been updated with new information.
