Poison ivy on ankle


Poison Ivy

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Poison ivy is a plant that can cause an itchy rash when touched. Poison ivy, poison oak, and poison sumac all contain urushiol (yoo-ROO-shee-ol), a sticky, colorless, odorless oil. Urushiol is not poisonous. It’s considered an allergen because it causes an allergic reaction in most people who touch it.

What Are the Signs & Symptoms of Poison Ivy?

The allergic reaction to poison ivy includes a rash with blisters, itching, and sometimes swelling. The rash can look like straight lines if the plant brushed against the skin that way.

After a few days, the oozing blisters become crusty and start to flake off. The rash from poison ivy can start within hours of contact or as much as 5 days later. It may take 2 to 3 weeks to heal.

How Is Poison Ivy Treated?

If your child comes into contact with poison ivy/oak/sumac:

  • Remove and wash any clothing that touched the plant.
  • Gently wash your child’s skin and scrub under fingernails right away with soap and cool water.
  • Cut fingernails short to keep your child from breaking the skin when scratching. Broken skin can let bacteria in, causing infection.
  • Place cool compresses on the skin as needed.

For itching:

  • Add oatmeal to the bath.
  • Use calamine lotion on the skin (but not on the face or on the genitals).

For nighttime help: If your doctor recommends it, give your child an over-the-counter oral antihistamine (Benadryl or a store brand). This might not stop itching, but it can make your child drowsy and better able to ignore nighttime itching.

When Should I Call the Doctor?

Call your doctor if your child has any kind of rash, especially with a fever. Home treatment can manage most poison ivy/oak/sumac rashes. But get medical care if the skin looks infected (with increasing redness, warmth, pain, swelling or pus) or the rash:

  • covers a large part of the body
  • is on the face or genitals
  • gets worse despite home treatment

For more severe cases, doctors sometimes prescribe pills or creams with steroids (not the same type of steroids that bodybuilders use) to decrease itching and redness. If the skin looks infected, the doctor may prescribe antibiotics.

Is Poison Ivy Contagious?

The poison ivy rash itself isn’t contagious. Fluid from a blister can’t spread the rash. But it is possible to get a rash from poison ivy without touching a plant. Urushiol can transfer from one person to another from their skin or clothing. Kids also can pick it up from anything that’s been in contact with the oil, including pets. Urushiol can even travel through the air if someone burns the plants to clear brush.

How Can We Protect Kids From Poison Ivy?

Poison ivy can grow anywhere — from forests to backyards. And it’s hard to identify: The leaves of poison plants blend right in with other plants and brush. Plus, there are several types of poison ivy, and each one can look different depending on the time of year.

The leaves of poison ivy plants release urushiol when they’re bumped, torn, or brushed against. When the oil is released, the leaves may look shiny or have black spots. Then, it easily can get on skin.

Here are some tips to help kids avoid getting a rash from poison ivy:

  • Teach them how to identify poison ivy, oak, and sumac, so they can steer clear of them (they should be especially careful of plants if the leaves look shiny).
  • Tell them to avoid areas where you know there’s poison ivy.
  • Have them wear long sleeves and long pants when in areas where poison ivy might grow.
  • If your dog has been outside exploring the woods, give him a bath to wash off any urushiol oil that may be on his coat.
  • If your kids touch urushiol oil, have them try to wash it off their skin right away by taking a shower and using lots of soap.

Reviewed by: Elana Pearl Ben-Joseph, MD Date reviewed: August 2019

Poison Ivy – Oak – Sumac

Is this your child’s symptom?

  • A very itchy rash with blisters
  • Caused by contact with the poison ivy plant

Symptoms of Poison Ivy

  • Rash is shaped like streaks or lines.
  • Red streaks with weeping blisters.
  • Rash found on exposed body surfaces (such as the hands). Also, can be on areas touched by the hands. Areas that can be affected in this way are the face or genitals.
  • Very itchy.
  • Onset 1 or 2 days after child was in a forest or field.


  • Caused by oil from poison ivy, poison oak, and poison sumac plants.
  • The oil is found in the leaves, stems, berries and roots of the plant.
  • Oil may be carried on pet’s fur.
  • The oil from the plant causes the skin to itch, turn red and blister.

When to Call for Poison Ivy – Oak – Sumac

Call Doctor or Seek Care Now

  • Fever and looks infected (spreading redness or pus)
  • Your child looks or acts very sick
  • You think your child needs to be seen, and the problem is urgent

Call Doctor Within 24 Hours

  • Looks infected (spreading redness or pus) and no fever
  • Swelling is severe (such as the eyes are swollen shut)
  • Severe poison ivy reaction in the past
  • Rash covers more than one fourth of the body
  • Face, eyes, lips or genitals have a rash
  • Severe itching (such as can’t sleep)
  • Big blisters or sores
  • Taking oral steroids for more than 24 hours and rash getting worse
  • You think your child needs to be seen, but the problem is not urgent

Call Doctor During Office Hours

  • Rash lasts more than 3 weeks
  • You have other questions or concerns

Self Care at Home

  • Mild poison ivy or sumac rash

Seattle Children’s Urgent Care Locations

If your child’s illness or injury is life-threatening, call 911.

Care Advice for Mild Poison Ivy

  1. What You Should Know About Poison Ivy:
    • Poison ivy is caused by skin contact with the oil from the plant.
    • The oil can also come from the fur of outdoor pets.
    • Most poison ivy rashes can be treated at home.
    • Here is some care advice that should help.
  2. Steroid Cream for Itching:
    • To help with the itch, put 1% hydrocortisone cream (such as Cortaid) on the rash.
    • No prescription is needed.
    • Use 3 times per day.
  3. Cold Soaks for Itching:
    • Soak the involved area in cool water for 20 minutes.
    • You can also rub the rash with an ice cube.
    • Do as often as needed to help the itching and oozing.
  4. Allergy Medicine for Itching:
    • If itching persists, give an allergy medicine (such as Benadryl) by mouth.
    • Use every 6 hours as needed.
    • No prescription is needed.
  5. Try Not to Scratch:
    • Cut the fingernails short.
    • Help your child not to scratch.
    • Reason: Prevent a skin infection from bacteria.
  6. More Poison Ivy – Prevention:
    • New blisters may occur several days after the first ones. This means your child probably has ongoing contact with poison ivy oil.
    • To prevent it from coming back, bathe all dogs or other pets.
    • Wash all clothes and shoes that your child wore on the day of contact.
  7. Return to School:
    • Poison ivy or oak cannot be spread to others.
    • The fluid from the blisters or rash can’t cause poison ivy.
    • No need to miss any school or child care.
  8. What to Expect:
    • Most often, the rash lasts 2 weeks.
    • Treatment can reduce the severity of symptoms.
    • Treatment does not change how long they last.
  9. Call Your Doctor If:
    • Poison ivy lasts for more than 3 weeks
    • It looks infected
    • You think your child needs to be seen
    • Your child becomes worse

And remember, contact your doctor if your child develops any of the ‘Call Your Doctor’ symptoms.

Disclaimer: this health information is for educational purposes only. You, the reader, assume full responsibility for how you choose to use it.

Last Reviewed: 02/01/2020

Last Revised: 03/14/2019

Copyright 2000-2019 Schmitt Pediatric Guidelines LLC.

THURSDAY, April 23, 2015 (HealthDay News) — Itchy, blistering rashes from poison ivy, oak and sumac are common and are caused by an oil in the plants called urushiol.

Usually, you can deal with these rashes at home, the American Academy of Dermatology (AAD) says. But you should go to the emergency room immediately if you have any of the following symptoms:

  • Trouble breathing or swallowing,
  • The rash covers most of your body, you have many rashes or blisters, or the rash develops anywhere on your face or genitals,
  • You develop swelling, especially if an eyelid swells shut,
  • Much of your skin itches, or nothing eases the itch.

If you don’t have any of these symptoms, you can probably treat the rash at home, according to the AAD.

If you know you’ve touched poison ivy, poison oak or poison sumac, immediately rinse your skin with lukewarm, soapy water. This may remove some of the oil from the plants. Thoroughly wash all the clothes you were wearing when you came into contact with plant. The oil can stick to clothing and cause another rash if contaminated clothing touches your skin.

You also need to use warm, soapy water to wash everything that might have the oil on its surface, such as gardening tools, golf clubs, leashes and even your pet’s fur.

Avoid scratching, which can cause an infection. And, leave blisters alone. Taking short, lukewarm baths with an oatmeal preparation you can buy at a drugstore, or with one cup of baking soda added to the water, can help ease itching. Short, cool showers may also help.

Other ways to relieve itching include putting calamine lotion or hydrocortisone cream on your skin. Applying cool compresses may also help ease itching. Make a cool compress by wetting a clean washcloth with cold water and wringing it out so that it does not drip.

Antihistamine pills can also reduce itching, but use them with caution, the AAD noted. Do not apply antihistamines to the skin. Doing so could worsen the rash and itch, the AAD said.

See a doctor if the rash does not improve within seven to 10 days, or if you think you may have an infection.

More information

The U.S. National Library of Medicine has more about poison ivy, sumac and oak.

The Truth About Poison Ivy

Picture it: It’s 1948. You’re 12, and you’re itching. Then a rash develops. Your mother says you probably have poison ivy—and sure enough, you’ve been thrashing about in the woods where they told you not to go (but you didn’t listen). It never hurt you before, but now the blisters are coming, in long streaks, on your legs and arms. There’s no sleeping and no holding still, not even in church. The itching is so bad, and vinegar and the pink stuff they put on you don’t help at all; they only call more attention to your rash. Everyone, even your own family, is giving you a wide berth, because they all believe poison ivy is contagious.

Six weeks later, the rash and itching are finally gone—but not the memory of this common condition, for which no effective treatment will exist until topical corticosteroids are introduced in 1951.

All these years later, many myths about poison ivy persist. Some are such powerful misconceptions that many people cannot be swayed from them, even by facts. For example, poison ivy is not in the least contagious. Nor is it caused by any kind of “poison.”

The culprit is an oleoresin known as urushiol. This oily resin is contained in the stems, leaves, and flowers of plants from the Toxicodendron genus, which includes poison ivy (by far the most common source), poison oak (found almost exclusively west of the Rockies) and poison sumac (found in limited areas of the southeastern United States). Similar reactions can be caused by exposure to other botanicals, including ficus, fern, fig, mango, and Japanese lacquer trees. (Another member of the Toxicodendron family is the Rhus tree, found mostly in Australia, where it is notorious for causing rashes.)

A history of recent exposure to the great outdoors can therefore usually be obtained, although exposure can also occur through contact with pets or with the clothing of family members who have been exposed. A live plant is not necessary. Many a victim has acquired poison ivy from clearing brush or handling firewood in the dead of winter. (The antigen can also be acquired through an airborne route, such as from the smoke generated by burning brush—even at a considerable distance.) Repeated exposure to poison ivy over several years’ time is required, which explains why children and city-dwelling adults may appear to be immune.

Typically, the blisters begin to appear within 12 to 48 hours of exposure (with some notable exceptions). Much to the consternation of the patient and family, new lesions can continue to manifest for up to two weeks after initial exposure, which is probably why so many people think poison ivy is contagious. The truth is, there is no urushiol in the fluid from the blisters, nor is the antigen “poison” in any way. In short, poison ivy cannot be transmitted from one person to another.

Poison ivy rashes manifest in several different ways. The most common is a type IV delayed hypersensitivity reaction, with pathognomic linear streaks of erythematous patches of edematous, blistery skin. Figure 1 shows a classic linear lesion on the face of a 69-year-old woman who had cleaned out her fence line a few days previously. This particular patient had a similar rash on her chest.

Figure 2 shows a more atypical form of poison ivy, entirely lacking linear lesions or even blisters. The patient’s rash was widespread, but concentrated on popliteal and antecubital areas and medial thighs. It comprised large sheets of highly erythematous skin, in the centers of which were targetoid reddish blue patches. This is a variant of erythema multiforme, which is by definition a secondary condition usually triggered by bugs (strep, herpes simplex virus) or drugs (sulfa, tetracycline, aspirin, penicillin) but occasionally by an exaggerated reaction to antigens such as poison ivy. In this case, this 185-pound 47-year-old woman and her family acquired poison ivy while picking wildflowers in wet weeds—bringing a rapid end to the family vacation.

The most effective treatment for severe, symptomatic poison ivy is the use of systemic glucocorticoids (eg, prednisone) and/or intramuscular injection of a corticosteroid (eg, triamcinolone). Patient 2’s condition was so severe that she couldn’t sleep, eat, or even drive a car. (Interestingly enough, she was the only one who sought medical evaluation. The rest of her family was content to clean out the local pharmacy’s supply of calamine lotion and diphenhydramine capsules.) Severity of this nature demands serious medication—in this case, a two-week taper of prednisone (from 60 mg down to 20 mg) plus an IM injection of triamcinolone (60 mg).

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Leaves of three, let them be! You’ve probably heard that little rhyme about poison ivy. But did you know that the plants poison ivy, poison oak, and poison sumac all contain the same rash-causing substance? It’s called urushiol (pronounced: yoo-ROO-shee-ol), a colorless, odorless oil (called resin) found in their leaves.

Urushiol is considered an allergen because it causes an allergic reaction. The poison ivy reaction takes the form of a rash, itching, and sometimes swelling. Not everyone gets a reaction to urushiol, but most people do. This reaction can start within hours of coming into contact with urushiol or up to 5 days later.

Typically, the skin becomes red, itchy, and swollen and blisters will appear. After a few days, the blisters may become crusty and start to flake off. The rash that people get from poison ivy can take 2 to 3 weeks to heal.

It’s a good idea to call your doctor if you have any kind of rash, especially if you have a fever too. If your rash is from poison ivy or a similar plant, the doctor may tell you to take cool showers and to use a soothing lotion, such as calamine lotion.

In more severe cases, doctors may prescribe pills or creams that contain antihistamines or steroids (not the same type of steroids that bodybuilders use!) to decrease itching and redness.

The poison ivy rash itself isn’t contagious. Fluid from a blister can’t spread the rash. But it is possible to get a rash from poison ivy without touching a plant. Urushiol can transfer from one person to another from their skin or clothing. Urushiol can even travel through the air if someone burns the plants to clear brush.

How Can I Protect Myself From Poison Ivy?

Poison ivy can grow anywhere — from the woods to your own backyard. And it can be hard to see: The leaves of poison plants blend right in with other plants and brush. Plus, there are several types of poison ivy, and each one can look different depending on the time of year.

The leaves of poison ivy plants release urushiol when they’re bumped, torn, or brushed against. When the resin is released, the leaves may look shiny or have black spots. Then, it can get on a person’s skin.

Here are some tips to help you avoid getting a rash from poison ivy:

  • Learn to identify poison ivy, oak, and sumac, so you can steer clear of them. (Be especially careful of plants if the leaves look shiny.)
  • Avoid areas where you know there’s poison ivy.
  • Wear long sleeves and long pants when you’re in areas where poison ivy might grow.
  • If your dog has been out exploring the woods, give him a shower to wash off any urushiol oil that may be on his coat.

If you come into contact with urushiol oil, try to wash it off your skin right away by taking a shower and using lots of soap. Don’t take a bath — the oil can get in the bath water and spread to other areas of your body.

Reviewed by: Elana Pearl Ben-Joseph, MD Date reviewed: August 2019

What Is Poison Ivy?

Jump to: Signs and symptoms | Causes | Poison ivy rash pictures | Poison ivy plant pictures | Diagnosis | Treatment | How long does it last? | Home remedies | Is it contagious? | Prevent it from spreading | Dogs and poison ivy |Get rid of poison ivy plants

Poison ivy is a poisonous plant that can cause a skin rash in people who come into contact with the leaves, stem, or roots. This rash, known as contact dermatitis or rhus dermatitis, is actually an allergic reaction to the urushiol oil (which is found in poison ivy, poison oak, and poison sumac plants) produced by the toxic vine. You can also get a poison ivy rash from touching an object (such as a piece of clothing) that has urushiol oil on it. And if you inhale smoke from burning poison ivy, you can experience a reaction in your respiratory passages.

Up to 85% of people will develop this rash if they come into contact with poison ivy. The hallmark poison ivy rash is red, itchy, and swollen, and can also have hives or blisters. You’ll likely know what it is when you see it, although a doctor can tell you if the rash is caused by something else. Most cases of poison ivy rash go away on their own within a couple of weeks. Over-the-counter creams and lotions can help ease the itch. In rare cases, poison ivy can cause more serious complications that may require medical treatment.

RELATED: Is It a Poison Ivy Rash? How to Tell-and How to Treat It

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Signs and symptoms of poison ivy rash

About 15% of people are immune to urushiol oil and wouldn’t know if they had a close encounter with a poison ivy plant. The remaining 85% will certainly know it, though perhaps not right away. Evidence that you’ve tangled with poison ivy can take hours or days to appear, depending on how sensitive you are and how much urushiol oil came into contact with your skin.

The main sign of poison ivy is a raised red rash where your skin has touched urushiol oil. The rash may show up in patches, lines, or streaks, which follow where the poison ivy came in contact with your skin. A poison ivy rash is usually also accompanied by swelling, hives, and bumps or blisters that can be either large or small. A few days after they first appear, the blisters can crust and burst, letting loose a clear liquid. The rash may show up on different parts of the body at different times depending on how much oil came in contact with that particular area of the skin.

In more severe cases, poison-ivy rash can spread to your eyes, mouth, or genitals, and blisters may get infected with pus. (If the oil is on your hands, you can spread it to other parts of your body.) If you’ve inhaled urushiol soot, you may have trouble breathing.

Signs and symptoms of poison ivy should usually resolve within a few weeks. Anything longer than this probably needs a doctor’s attention.

In milder cases:

  • Raised red rash
  • Swelling
  • Hives
  • Bumps or blisters
  • Itchiness

In more severe cases:

  • Difficulty breathing
  • Eyes swollen shut

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What causes poison ivy rash?

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A poison ivy rash is caused by urushiol oil from a poison ivy plant coming into contact with skin. The skin quickly absorbs the oil, which then causes the hallmark rash. Contact with any part of the poison ivy plant—the roots, stem, or leaves—can cause this rash. You can come into contact with urushiol oil either by touching a poison ivy plant directly, or by touching something else that has oil on it, such a gardening tool, a pair of shoes, or a pet’s fur. Urushiol oil doesn’t stay on the skin for very long, but it can stay on objects for years—which means you can easily develop a rash after touching anything that has urushiol oil on it. If the oil is still on your fingers, you can spread the rash to other parts of the body.

You usually cannot get the rash by touching another person who has touched a poison ivy plant because the oil is absorbed into the body so quickly. You also cannot get a rash from liquid out of a burst blister.

In some cases, you can inhale urushiol particles—or get them on your skin—from poison ivy plants that are burning nearby.

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Poison ivy rash pictures

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Poison ivy rash can appear anywhere your skin has come into contact with the plant. The rash is red and can be irregularly shaped, or can appear as a line or streak (essentially, the rash will be an imprint of where you brushed against leaves or any other part of the plant). It’s usually accompanied by swelling, hives, and bumps or blisters.

Image zoom John Kaprielian/Getty Images

A few days after the rash first appears, the blisters will crust over and burst, releasing a clear liquid.

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The rash may appear on different parts of the body at different times depending on whether that area touched a little or a lot of oil. In severe cases, the rash can spread to your eyes, mouth, or genitals. If this happens, contact your doctor.

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Poison ivy plant pictures

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Poison ivy grows either as a vine or as a shrub in most parts of the U.S. with the exception of Alaska, Hawaii, and certain areas along the West Coast. The plant is known for the three leaflets that grow on each leaf, a trait that gave rise to the famous warning phrase, “Leaves of three, let them be.

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The leaflets can be rounded or have multiple jagged edges. The plants are usually green around a red stem but may also be red, brown, or green with black dots (this is urushiol) depending on what time of year it is and where they’re located. Poison ivy may sport berries—yellowish white, orange, red, or yellowish green depending on the season.

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How is poison ivy rash diagnosed?

Most cases of poison ivy are obvious just by looking at the rash, and if you know that you have come into contact with foliage. The rash will be red, swollen, and itchy and usually has hives and small or large bumps or blisters. The blisters usually last a couple of days before they burst, giving off a clear liquid. Don’t be surprised if the rash looks different on various parts of your body at different times. This is normal and doesn’t necessarily mean the rash is getting worse.

A doctor, particularly a dermatologist, can provide a more definitive diagnosis. He or she can also help you rule out other causes.

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Poison ivy treatment

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There is no cure for poison ivy rash. It will usually go away on its own, even if you do nothing. Fortunately, there are treatments to relieve symptoms, the most bothersome of which is itching.

If you develop a rash, don’t scratch it. Instead, try one of many over-the-counter products that are available to tame the itch, such as calamine lotion or hydrocortisone cream. Oral antihistamine pills can also reduce itching and may help you sleep.

If your rash doesn’t show signs of abating after a week or 10 days, contact your doctor. He or she may prescribe a stronger steroid ointment and, if you have signs of an infection (swelling, pain, pus around the rash, or a rash that is warm to the touch), an antibiotic.

Contact your doctor or go the ER if you develop a temperature over 100 degrees, the rash spreads to your genitals, eyes or mouth, you have trouble breathing, your tongue or throat starts swelling, or the rash covers more than a quarter of your body.

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How long does poison ivy rash last?

It’s hard to know how long symptoms from poison ivy will last. It usually depends on how sensitive you are and how much oil got on your skin. A poison ivy rash that lasts one to three weeks is not unusual. The first signs (red, swollen, itchy skin along with blisters) can develop hours or days after first contact with a poison ivy plant. A few days later, the blisters will get crusty and drop off. A poison ivy rash may also show up on different parts of your body at different times depending on how much urushiol oil landed on certain areas. The skin usually absorbs the oil quickly, but it can linger on objects for years. If your rash doesn’t go away in a couple of weeks, contact your doctor.

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Poison ivy rash home remedies

Simple home remedies can help ease itch from a poison ivy rash. Bathing in cool water can be a huge help, as can pressing a damp cloth (make sure it’s cool as well) on the itchy area for 15 or 30 minutes at various times throughout the day. Avoid hot water, as that can worsen the rash. Many people find that soaking in a colloidal oatmeal bath (you can make your own or buy a product at the drug store) also does the trick. Some experts recommend easing blisters with a solution of one or two Dome-Boro tablets (available at most drug stores) dropped in a pint of water.

Poison ivy rash medications

  • Calamine lotion to relieve itch
  • Hydrocortisone cream to relieve itch
  • Oral antihistamines such as Benadryl to relieve itch
  • Antibiotics to heal a bacterial infection around the rash
  • Steroids in more severe cases to reduce swelling, redness, and itching

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Is poison ivy contagious?

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You can’t get poison ivy from another person unless the person still has urushiol oil on their skin. This is unlikely, though, since skin absorbs the oil very quickly. You can also spread poison ivy on your own body if oil is still on your fingers or under your nails and you then touch other parts of your body.

The real danger is getting a poison ivy rash from dogs that have urushiol oil on their fur, or inanimate objects, where urushiol oil can hang on for years. This can include clothing, shoes, gloves, garden tools, your dog’s leash, and more. Be careful when touching your dog after it has been rollicking in the woods. And if you suspect an object has urushiol oil on it, clean it with rubbing alcohol or soapy water.

You can’t get a rash from fluid coming out of a burst blister, although you can develop a rash after touching a dead poison ivy plant.

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How to prevent poison ivy rash from spreading

If you’re going outdoors and think you might come into contact with poison ivy, use an over-the-counter barrier cream as a buffer between urushiol oil and your skin. You can also protect yourself by wearing long pants, long sleeves, gloves, and boots.

If urushiol oil from a plant does gets on your skin, it could spread to other parts of your body if you touch the oil with your fingers then touch another part of your body. If you think you’ve been exposed recently, rinse your skin with lukewarm soapy water or take a cool shower (not a bath, as that could spread the oil further). Brush vigorously under your nails.

Urushiol oil can linger on inanimate objects such as clothes, shoes, rakes or other gardening tools. Wash clothes and shoes, and use rubbing alcohol or soap and water on tools.

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Can dogs get poison ivy?

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Although dogs usually don’t get poison ivy rash, they can easily get urushiol oil on their fur from being in the woods or backyard, or just going for a neighborhood walk. And you may get a poison ivy rash from petting a dog. If you suspect your dog has been in contact with poison ivy, wash him or her right away while wearing rubber gloves and goggles in case they shake off the water. If you dry your dog with a towel, throw it in the washing machine and let your dog dry off fully before petting him or her again. You should also wash your dog’s leash, collar, and any other objects that may have urushiol on it.

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How to safely get rid of poison ivy plants

If there are poison ivy plants in your yard, you can get rid of them yourself or hire a professional to do it for you. If doing it yourself, make sure you can accurately identify the plant first. When you’re ready to start the eradication, wear thick gloves, boots, long sleeves, and pants to make sure you don’t get it on you. Poison ivy can be pulled out of the ground like a weed, but make sure you get the roots. Some people use an herbicide as well. Bear in mind that you can still get poison ivy rash from dead plants. Don’t burn poison ivy—smoke from the burn will contain urushiol oil. Once you’re done removing poison ivy, or at least done for the day, wash all your clothes and anything that may have come into contact with the poison ivy. And wash yourself—especially your hands—and scrub under your nails even if you’ve been wearing gloves.

A stroll in the woods is nearly always an enjoyable endeavor; what’s not so enjoyable is discovering a red, itchy rash the next day. Each year, millions of Americans come in contact with poison ivy, poison oak, or poison sumac. While there are numerous other poisonous plants, these three are grouped together because they share a common irritant: an oily resin/sap called urushiol. This resin is potent — it only takes 1 nanogram to cause a reaction. And unfortunately, it coats all parts of these plants.

While some of the characteristics we describe below aren’t necessarily unique to these plants, we’ll get you enough information to avoid these poisonous foes and confidently walk your favorite trails (or create your own!).

Identifying Poison Ivy

The old saying is true: “Leaves of three, let them be!” While there are other plants which have leaf clusters in threes, both poison ivy and poison oak share this trait, making it best to avoid plants with this feature altogether. What you’ll most likely encounter with poison ivy is a stem with a larger leaf at the end, and two smaller leaves shooting off the sides. The leaves can be notched or smooth on the edges, and they have pointed tips. The plant is reddish in the spring, green in summer, and yellow/orange in the fall. It’s not uncommon to see clusters of greenish-white berries on poison ivy through the spring and summer, as well as green/yellow flowers.

Poison ivy can take the form of a vine or a shrub. The plant’s appearance varies widely based on the region and specific environment where it grows, which is everywhere in the US with the exceptions of Hawaii, Alaska, and parts of the southwest deserts.

Identifying Poison Oak

Like poison ivy, this plant most often grows leaves in clusters of three, although some varieties display five or seven per cluster. The defining feature is that the leaves have a lobed, wavy appearance (also described as scalloped), similar to oak tree leaves, but more subdued. Another characteristic that sets it apart from poison ivy is that the tips of the leaves are rounded rather than pointed. Its leaves are bright green in spring, turn yellow-green or pink in summer, and finally turn yellow into dark brown in the fall.

Poison oak is generally a shrub, averaging about 3 feet tall, but shoots of it can also grow as a vine. Not commonly found in the middle part of the U.S., poison oak is primarily situated on the West coast, and the East coast/Southeast.

Identifying Poison Sumac

Poison sumac stems (which are generally red — another of the defining features) have 7-13 leaves, in pairs, with a lone leaf at the end. Leaves are oval, elongated, and smooth-edged, usually 2-4 inches long. They are bright orange in spring, dark green in summer, and red-orange in fall.

Poison sumac thrives in watery, swampy environs, present mostly in the Midwest and Southeastern U.S., where high humidity is common. It grows as a tree or tall shrub, 5-20 feet tall.

Allergic Reactions to Poison Ivy, Oak, or Sumac

An allergic reaction to poison ivy, oak, or sumac can occur when your skin makes direct contact with the plant, when you touch something that has been in contact with the plant, and even when the plant is burned, as particles of urushiol can make their way into your eyes, nose, and throat. Urushiol is very sticky and tenacious, so it easily adheres to firewood, dog fur, and gardening tools, and then transfers itself to your skin once you lift, pet, and pick up these things. Because urushiol is present in the plants’ roots, stems, and leaves, it remains potentially poisonous even in the wintertime.

Anyone can get an allergic reaction if exposed to urushiol in a large enough dose. But some folks are more sensitive than others. About 85% of the population is fairly to extremely susceptible to getting an allergic reaction, while 15% of lucky folks are resistant to reaction. One’s sensitivity/resistance is thought to be largely genetic in origin, so if your parents have had severe reactions to poisonous plants, take extra care to avoid contact yourself.

Sometimes you only get a rash after being exposed to the plant numerous times. So don’t automatically assume that you’re resistant because you touched poison ivy/oak/sumac once, and didn’t get a rash.

On the other hand, sensitivity to these poisonous plants can lessen over time. So if you had a bad reaction as a child, you may have developed more resistance over the years.

How to Treat a Rash From Poison Ivy, Oak, or Sumac

If you know you’ve touched one of these poisonous plants, you have about 10 minutes before the sap penetrates the lower layers of your skin and binds to its cells, at which point an allergic reaction will set in. So you can head off this reaction by immediately rinsing the exposed area with running water. Use a mild detergent soap if you have it; fatty soaps can spread the urushiol oil, creating a worse reaction. Rinsing with rubbing alcohol is also effective. If wipes are all you have to clean the area, that’s better than nothing.

If you don’t wash off the resin in time, and you’re sensitive to ivy/oak/sumac, then a rash will develop. Rashes from all three of these plants appear in the same form and are treated in the same way since the irritating agent in all of them is urushiol. If you’ve been outdoors and have the following symptoms appear, you may have a rash from one of these plants:

  • patches of swollen redness
  • outbreak of blisters
  • intense itching

These are the primary symptoms, and they generally appear within 12-72 hours of contact. Luckily, if the rash isn’t severe, it can be treated at home without having to see a dermatologist.

The American Academy of Dermatology recommends the following treatment plan:

  • Immediately rinse your skin with lukewarm, soapy water. Urushiol is an oil, so if not washed off, it can continue to spread. (Note: there are special washes out there that claim to remove urushiol more effectively and to lesson the severity of a rash once a reaction has set in; Zanfel is a popular one, but Mean Green Scrub uses the same ingredients/composition but costs way less per ounce.)
  • Wash your clothing and anything else the oil may have touched, including tools, pets, car seats, etc.
  • Do not scratch; doing so can open the skin and possibly cause an infection.
  • Leave blisters alone; do not peel overlying skin, as it protects the wound underneath from infection.
  • Apply calamine lotion or hydrocortisone cream/lotion.
  • Apply a cool washcloth to skin to ease burning and itching.

The rash should heal in about 1-2 weeks. Though it may look gross, it’s not contagious. If the rash is particularly large or painful, or doesn’t heal in that timeframe, it’s best to see a dermatologist who may prescribe a round of oral steroids or other treatments.

Above all, wearing long clothing when you go out is recommended — especially pants to guard against brushing these plants while wandering around. Be sure to wash these clothes right when you get home.

You’re now equipped to head out to the woods and avoid these itchy fiends!

Poison ivy, oak, and sumac: Who gets a rash, and is it contagious?

Avoid areas where poisonous plants grow

So many people develop a rash from poison ivy, oak, or sumac that it’s important to avoid areas where these plants grow.

Poison ivy, oak, and sumac all contain an oil called urushiol (yur-oo-shee-aal). If you have an allergic reaction to this oil, you can develop a rash. Because most people are allergic to this oil, just about everyone who comes into contact with it develops a rash.

The more exposure you have to these plants, the more severe your allergic reaction tends to be. Some people who work outdoors must leave their jobs. Others need to stop a favorite outdoor pastime because they develop such a severe allergic reaction.

You’ll also find a few people who seem immune. They never develop a rash. That doesn’t mean that they will never get a rash from one of these plants. Our bodies change, so it’s always wise to avoid touching these plants.

Can babies get a rash from poison ivy, oak, or sumac?

Anyone can have an allergic reaction to one of these plants, even a baby.

The rash looks the same in children and adults.

If you’re seeing a poison-ivy type rash on your child’s skin for the first time, dermatologists recommend that you take your child to your healthcare provider. Some health conditions can cause a rash that looks similar to a poison ivy rash.

Can you get a rash from one of these plants in the winter?

Yes. These plants are poisonous year-round. Touching any part of these plants, including the roots, can cause a rash, even during the winter.

Can you get a poison ivy rash from someone else?

The rash isn’t contagious. If someone has a rash, touching that rash won’t cause a rash on your skin. You can develop a rash, if you touch the person’s skin or clothing while oil from one of these plants is still on it.

Can you get a poison ivy rash from a dog or cat?

Yes, the oil that causes this rash can stick to just about anything, including fur.

If your pet has brushed up against one of these plants, you can get the oil that causes the rash on your skin when you touch your pet. This could lead to a rash.

To prevent getting a rash this way, bathe your pet anytime you suspect it has been near poisonous plants. Just be sure to wear rubber gloves while rounding up and bathing your pet.

You don’t have to worry about your pet getting a rash. Most pets are not allergic to these plants.

If you live in an area where you or your pet comes into contact with these plants often, you can take steps to prevent a rash. You’ll find out what to do at: Poison ivy, oak, or sumac: How can I prevent a rash?

Getty Images

Centers for Disease Control (CDC). “Poisonous plants: Recommendations.” Page lasted updated 6/1/2018. Last accessed 6/5/2019.

McGovern TW. “Dermatoses due to plants.” In: Bolognia JL, et al. Dermatology. (second edition). Mosby Elsevier, Spain, 2008: 255-6.

Vaught CK, Mold JW. “Poison ivy: How effective are available treatments?” J Fam Pract. 2016;65(11):801-9.

Poison Oak photos and remedies – superbloom

Well, it’s 2019 and with record rains, the superbloom phenomenon of flowers is so vibrant it’s visible from satellite photos from space. Unfortunately, this life force of water and sun have boosted the poison oak harvest as well. It’s out in force and it’s about to explode as the warm weather arrives.

The single most important measure is avoidance. One needs to know where the local poison oak thrives and avoid that area for the first few months of spring. Then, coverage is key is as any barrier between the plant and human skin will pay dividends. Finally, when one touches the plant, proper cleaning, treatment should be performed meticulously. And when one gets a major outbreak. Absolutely consult with your physician as the most effective treatment, prescription steroids can only be safely prescribed by a doctor.

Prime mountain biking season for the warmer parts of the country. Mtbr is based in Northern California and we’ve had the driest January and February on record. Poison oak shoots are already exploding in their red, juicy glory. This is a good time to brush up on your poison knowledge as identification and prevention is key.

“Causes severe itching, evolves into inflammation, colorless bumps, and then blistering when scratched.”

We are not botanists but it is our business to understand this evil weed as it affects our mountain biking. No other trail hazard out there can be as damaging and bothersome to our riding. The problem is, it doesn’t have barbs or jagged edges that will cut us and let us know that damage has been done. It is like a seed that will incubate over the next day or two. And when it’s ready to do damage, it can fester for weeks and months. It is not just an itch. It is a burning, skin eating disease that can stop us from riding, getting out in the outdoors, drinking beer. Basically, it can land us in the hospital. So read on and be informed.

What is it?

Poison oak, poison ivy, and poison sumac are plants that contain an irritating, oily sap called urushiol. Urushiol triggers an allergic reaction when it comes into contact with skin, resulting in an itchy rash, which can appear within hours of exposure or up to several days later. A person can be exposed to urushiol directly or by touching objects — such as bike clothing, gardening tools, camping equipment, and even a pet’s fur — that have come into contact with the sap of one of the poison plants days or weeks earlier

Urushiol oil is found in all parts of these plants, including the leaves, stems, and roots, and is even present after the plant has died. Urushiol is absorbed quickly into the skin. It can also be inhaled if the poison plants are burned. The smoke may expose not only the skin to the chemical but also the nasal passages, throat, and lungs. Inhaled urushiol can cause a very serious allergic reaction and can surely land a person in the hospital as no topical cleaners or ointments can reach the body’s internals.

What does it look like?

Poison Oak is highly variable in appearance. It varies from shrub to vine. The leaves vary from red to green. It has long stems, leaves in threes, small greenish flowers, and smooth seeds that are about 1/4 inch across. It is often lush in coastal canyons but sparse in the mountain woodland. It is deciduous and often loses its leaves in late summer, leaving it hard to recognize. But the long, straight branches give a clue.

Poison-oak is usually a shrub, though it sometimes becomes a vine several inches in diameter that grows high into the oak trees attached by air-roots. The leaves DO come in threes. They are shiny, without prickers, and the middle leaf has a distinct stalk. It is harder to identify Poison Oak in the winter when it loses its leaves and looks like erect bare sticks coming from the ground. In the spring, it is easy to detect as the baby leaves shoot out in their full reddish glory. This is when the urushiol is most potent and the slightest contact with these reddish stacks will result in bad exposure.

Where is it found?

It is found in damp, semi-shady areas near running water and also thrives in direct sunlight, requiring water only in early spring. Any trail leading to a waterfall on California’s coast may likely be home to western poison oak; it can also be found in some inland mountain ranges, such as the Cascades.

It needs sunlight though so very shady places like redwood forests minimize the growth of these plants. Also, at higher elevation like over 6000 feet, they are not able to thrive.

The plant toxin produced by members of the genus Toxicodendron, called urushiol, is known for causing an uncomfortable, and sometimes painful, skin reaction. Urushiol is the main component of the oily resin that is found on the stems and leaves of poison ivy and several other related species (Hogan, 2008). It causes contact dermatitis — an immune-mediated skin inflammation (Kalish et al, 1994) — in four-fifths of humans.

What does it do?

Effects of poison oak are similar to those of poison ivy. It first causes severe itching, evolves into inflammation, colorless bumps, and then blistering when scratched. In late fall or winter, there are no leaves on the plants, so they can be difficult to recognize.

What do we do about it?

Read on for advice about poison oak.

Advice by Francois

1) Know what it looks like and where it lives – You need to get familiar with all its mutant forms and how to identify it quickly. In spring, it is fairly easy but when the red stalks are gone, you need to be able to tell just by leaf shape alone.

2) Do not go there – Once you know where it lives, just don’t go there when it’s peak season. Go somewhere else or go in that trail with a hazmat suit.

3) Dodge it – It takes years of training to ride singletrack at 20 mph, spot the poison oak and dodge it with full body english. You need to duck, hop, zig and zag. If you are going to make contact, slam on the brakes and walk. Do not touch it!

4) Wipe, wash, sterilize your gear immediately.

5) If you’ve made contact, you have a few hours to minimize the damage. This can be the difference between an itch for a day or a pure misery for weeks. Wash up with Technu Extreme, Turpentine, Dawn dishwashing detergent, a rough dry soap that breaks up oils.

6) Do not scratch. Do not sweat and don’t expose it to sunlight.

7) Do not experiment if you have a severe case. Don’t listen to the 1001 superstitions out there about sleeping upside down and eating honey from a poison oak honey bee. This is no time to risk failure.

8) If you are exposed. See a doctor and get the prescription for steroids. This is the only real cure. There is a cream, pills, shot for various severity of the exposure.

Advice by Sandra Baker

Oh my gosh, where to begin. I am a poison oak/poison ivy researcher.

After exposure to the plants, some of you actually go home or wait till you are in your car before you clean your skin. For the seriously allergic, you have only a few minutes before the oil starts being absorbed into your skin and the immune system is alerted. Others have more time. Why not have your skin cleanser of choice on your bike? For the unprepared—here is what you do. Did you see the post about mud? This writer was on the right path, except you don’t need water in the mixture. Dig down through the ground mulch to clay–real dirt. Clay attracts oil to itself. If the molecules are full of water, it can’t, and has to dry. So mud is okay if it has time to dry on your skin, but best is to take dry dirt and scrub your skin over and over with it.

You can smear your body with mud for your ride, but it will fall off. Easiest is Ivy Block, which is made from a special—yep—clay, and it does not show. It has been clinically tested and works pretty well supposedly.

Zanfel has been clinically tested, and can sometimes stave off a rash if you don’t wait too long to apply.

Bleach will dry the blisters up but can leave life long scars. Brake cleaner will get the oil off because it is composed of toxic petrochemicals. Tecnu has the least toxic petrochemical in it and works well.

For a rash, very hot water or a hairdryer moved in close, and removed before burning the skin works well. It too has been clinically tested and proven effective by acting on the itching nerve network. (yes itch has its own nerve network separate from the pain one. That’s why opiates will not touch itch). I used to get 6 hours of sleep from heat, but a hot shower doesn’t cut it. It has to be really hot, and you just put a limb under the water for a second or two.

My credentials: I wrote “The Poison Oak & Poison Ivy Survival Guide”

Advice by R3R3R

1) Avoidance: Learn to recognize it (that means during all seasons and at all speeds – I can even tell where it will usually grow and can identify it at speed on a mountain bike or a motorcycle). If you know it is there, avoids it. That can mean taking a different line on a trail, or even not taking a trail if you know it is overgrown.

2) Wash: Bring a water bottle with you (easier than rinsing with a hydration pack). If you know you have brushed against some, rinse with cool water as soon as possible. Do not rub, do not use soap, do not use chemicals. Rinse with cool water. If a stream is nearby, you might want to stick your arm/leg in or splash some water on the area of contact.

This is followed up by rinsing in a moderately cool shower as soon as possible after returning from a ride. Don’t forget to also wash all of your gear and even to wipe down your shoes and pedals (and any other parts that potentially came in contact). Otherwise, you will get contact exposure from those items later.

The reason why this method works is that water apparently neutralizes the urushiol oil (the toxin in poison oak/ivy/sumac) and also washes it off. The key is to wash before it penetrates the oil layer on your skin. Some folks can tolerate the urushiol on their skin for a long time. For me, it is about 3-6 hours (long enough for a ride). Some folks will get it, either way, esp. if the branch or leaves scratch your skin and break through the oil layer immediately. From what I’ve seen, keeping your oil layer intact is important (I also advise wearing full-length gloves and long sleeves if it is not too hot). If you use skin products or soaps before the ride that keeps your skin really dry (cleansers, alcohol, etc.) you could end up having less protection against poison oak.

I think that technu provides an additional barrier (the kind you put on in advance) but I don’t think it would stop a branch scratch. I think they also have a washing product as well. I don’t use any of that. I am careful not to touch the poison oak, and I rinse immediately if I think I have brushed it. After returning home, I rinse my gear and myself before soaping up or using any other products. I almost never get poison oak anymore (yet I ride around it all the time). The exceptions seem to be when it scratches me, or if I forget to wash my gear completely after a ride.

If you do get it, try not to scratch (it will spread, last longer, and may leave scars). I know, it is easier said than done…

Advice by Ebeer

Poison oak is spread by the oils in the plant. There are no great options for those are particularly sensitive, but these are some options that might “help”:

1) Wear long socks or pants

2) Use Ivy Block (supposed to create a chemical barrier that prevents or maybe discourages oils from absorbing into the skin)

3) Carry alcohol wipes or special Ivy wipes with you when you ride. Wipe down at breaks or when you think you may have been exposed

4) Wash immediately after rides. There are many options here: Maries Ivy Soap, Technu, etc. Many including myself report that Dawn dish soap is effective as any of the very expensive alternatives. The key is to wash quickly, wash with cool water, and get out of clothes that may have been exposed.

5) Do not scratch. EVER.

So share with us your unfortunate experiences. How badly have you been exposed? How do you combat this evil weed? What is your version of poison oak in your area?

Black-Spot Poison Ivy

Case Description

A 34-year-old otherwise healthy woman presented with a 10-day history of black “oil patches” on her left arm that began after exposure to her children’s toys, which had been left in an outdoor wooded area. Her first symptom was a severe burning sensation of the skin, which was followed by the development of black spots; she also noticed some small asymptomatic blisters. Six days after the onset of the black spots, she applied Neosporin ointment (Johnson&Johnson, New Brunswick, NJ) to the lesions. By the next day (day 7), the area had become quite painful, and she noticed erythema extending from her left wrist to her axilla. She discontinued Neosporin and started using topical hydrocortisone cream on the involved area. On day 8, she developed swelling in her left axilla and was treated at a local urgent care facility with oral prednisone (dose unknown). Because of concern for possible left-arm cellulitis, the patient was transferred to the University of Minnesota Medical Center, where she was seen in the dermatology department. On presentation, there were erythematous and edematous papules and plaques studded with vesicles on the left dorsal forearm. The left volar forearm had numerous black and erythematous plaques with edema, vesicles, and ulcerations (Fig 1). On the abdomen, left foot, bilateral legs, and right arm, there were focal target-shaped edematous erythematous blanching patches and plaques. There were also erythematous plaques in the pubic area and palpable lymph nodes in the left axilla. The next day, the urticarial eruption had spread to involve her back, neck, and periocular area. Her past medical history included seasonal allergic rhinitis and rhinitis in response to animal dander. She had no previous history of contact allergy. A skin biopsy specimen taken from a black plaque on the left volar arm showed dermal and epidermal necrosis, and a skin biopsy specimen from an urticarial plaque on the left arm was consistent with urticaria. Stains were negative for organisms. Blood, urine, and throat cultures were negative. Treatments included a methylprednisolone taper and diphenhydramine.

Figure 1.

Patient’s left volar forearm, with black spots and erythematous plaques with edema, vesiculation, and ulceration.

After discharge and 2 days after completing the oral prednisone taper, she developed immediate burning of the skin on the left face, neck, and arm shortly after handling her husband’s laundry, which may have been contaminated with poison ivy resin. On day 22 (10 days after discharge), the patient was seen at a local primary care clinic, where oral prednisone was reinitiated; however, the rash continued to worsen, and she was re-admitted to the hospital. On admission (day 23), she was observed to have periorbital erythema and edema with erythematous patches and small punctate black crusts on the anterior neck, abdomen, and left arm. Lyme antibodies and Coxsackie A virus titers were negative; erythrocyte sedimentation rate, C-reactive protein, and kidney function test results were within normal limits. A biopsy specimen from the abdomen demonstrated epidermal and dermal necrosis with a superficial and deep perivascular and periadnexal infiltrate of eosinophils.

Approximately 10 months later, the patient had a recurrence of her symptoms, this time with acute respiratory involvement. She was driving along the road near her property when freshly cut plant material blew in through the window. She experienced immediate intense burning of the left arm and anterior neck and developed difficulty breathing within a few moments. She injected herself with epinephrine and drove to the emergency room, where she was given another dose of epinephrine and intravenous steroids; however, she continued to have wheezing and became unable to phonate. She was immediately intubated and admitted to the hospital. She remained intubated for 4 days before discharge. During the hospitalization, erythema, blistering, and black spots developed in an airborne distribution on the arms and neck (Fig 2 and 3). She was treated with intravenous diphenhydramine, methyl prednisolone, and cimetidine.

Figure 2.

Black spots, erythema, and edema of the anterior neck.

Figure 3.

Black spots, erythema, and edema of the anterior neck.

Since the last episode, she has strictly avoided poison ivy exposure and has not had a recurrence of symptoms; however, she has developed significant scarring from the lesions on her arms and face (Fig 4). She declined further testing including patch testing with Neosporin.

Figure 4.

Scarring on left forearm at sites of black-spot poison ivy dermatitis.

Poison ivy (Toxicodendron radicans) is a toxic plant that causes an itchy and sometimes painful rash in most people when they touch it. A clear oil in the plant’s sap, called urushiol, causes the irritation. The reaction results in an itchy, red rash with bumps or blisters, according to the National Institutes of Health (NIH).


Poison ivy has several characteristic signs, according to About.com’s Poison Ivy Treatment Guide. Its leaves grow in clusters of three. The middle leaflet is longer than the other two, and the leaflets are wider at their base and are elliptical in shape, with small lobes. The plant’s stem has no thorns, but may have bunches of green or white berries. The stem may have aerial roots.

The almond-shaped leaves range in color from light green (young) to dark green (mature), but turn red, orange or yellow during the fall. Mature leaves are slightly shiny. Leaflets are typically about 1.2 to 4.7 inches (3 to 12 centimeters) long, but can be up to 12 in (30 cm). The leaves have a smooth surface with few or no teeth on their edges.

Where it’s found

Poison ivy grows throughout North America in all U.S. states east of the Rocky Mountains, the Canadian Maritime provinces, Quebec, Ontario, Manitoba and mountainous parts of Mexico, according to the USDA. It also grows in Asia in Japan, Taiwan, Russian islands and parts of China.

The distribution of Western poison ivy (left); and Eastern poison ivy (right). (Image credit: USDA)

Poison ivy is very common in suburban parts of New England, and in the Mid-Atlantic and southeastern regions of the United States. Poison oak, a similar plant species, grows in western North America, the West Coast of the U.S. and the U.S. Southeast, according to the Centers for Disease Control and Prevention (CDC).

The distribution of Pacific poison oak (left); and Atlantic poison oak (right). (Image credit: USDA)

Poison sumac (Toxicodendron vernix), which is related to poison ivies and poison oaks, is a woody shrub that grows primarily along the Mississippi River and boggy areas of the Southeast, in the United States, according to the CDC.

The distribution of poison sumac. (Image credit: USDA)

The poison ivy plant normally grows in wooded areas, especially in places where the sun shines through. It can also be found in rocky places or open fields.

Poison ivy flowers between May and June. Its yellowish- or greenish-white flowers grow in clusters slightly above the leaves. The plant has a grayish-white, berrylike fruit that matures in August to November. Not a true ivy, poison ivy can grow as a trailing vine, a climbing vine or a shrub.

This coarse, hairy growth on the trunk of a tree is a mature poison ivy vine. As indicated by the watch, the vine can easily grow to the size of a man’s wrist. The “hairs” allow the vine to grab onto the bark and grow up to the tops of even tall trees. All parts of the vine contain urushiol, including the hairs. Using a chain saw to cut down such a tree produces flying poisonous sawdust. (Image credit: New York Department of Transportation.)

Physical effects

Skin contact with poison ivy’s oils causes a red, streaky and patchy rash, extreme itching and red bumps that can form blisters. The rash is not contagious, but the oils can remain on clothing, shoes and other objects for a long time if not cleaned, and can cause rashes in the future, according to the NIH.

The inflammation of the skin is due to the body’s immune reaction to the plant oil, said Dr. Seemal Desai, a dermatologist and medical director at Innovative Dermatology in Plano, Texas.

“Usually you’ll see at the site of contact with the plant,” Desai told Live Science. “Sometimes it will be in a line, because the plant brushed by it in that pattern,” he said.

If you have a rash, you shouldn’t scratch it, Desai said. That will only help spread the rash.

Reactions to poison ivy range from mild to severe. The rash usually lasts a few days to a week, and is usually worst on days four to seven. On rare occasions, it can lead to hospitalization.

Poison oak and poison sumac also contain urushiol oil, and cause a similar skin reaction.

Poison ivy berries are a pale green when first formed, lightening to white as they mature. (Image credit: New York Department of Transportation.)


People exposed to poison ivy or related plants should wash the skin thoroughly with soap and warm water, ideally within half an hour, the NIH recommends. They should use a brush to scrub underneath the fingernails to prevent spreading the plant oil, and wash clothing and shoes with soap and hot water. Tools and other objects should be washed with a dilute bleach solution or rubbing alcohol.

The NIH says that heat and sweating can make itching worse, so exposed people should stay cool and use cool compresses on their skin. Calamine lotion and hydrocortisone cream may be used to ease itching and blistering. A lukewarm bath with oatmeal bath products or aluminum acetate may help with itching. Antihistamines may also be used.

“If children come in contact with work clothing contaminated with urushiol, a pediatrician should be contacted to determine appropriate dosage,” according to the CDC.

If the rash is severe, particularly around the face or genitals, a health care provider may prescribe steroids. The Food and Drug Administration (FDA) recommends contacting a doctor if you have any of the following symptoms: a fever above 100 degrees F; the rash shows pus, soft yellow scabs or tenderness; itching gets worse or keeps you awake at night; rash spreads to eyes, mouth, genitals, or to more than a quarter of your skin area; rash doesn’t improve in a few weeks; rash is widespread and severe; or you have difficulty breathing.

The left elbow of a man displays a rash that had been caused when he brushed against a poison ivy plant. (Image credit: CDC.)


To prevent poison ivy exposure, the NIH recommends that people wear long sleeves, long pants and socks in regions where the plant may be found. Applying ivy block lotion and similar products can reduce the risk of developing a rash if it is applied before exposure.

It may also be helpful to learn how to identify poison ivy plants. Remove (but do not burn) these plants if they are found near your home. (Smoke from burning poison ivy can also cause a reaction.) Pets can also carry the poisonous resins. If you are exposed to poison ivy, wash the area as soon as possible.

In some cases, there have been reports of people who have some resistance to the poison ivy oil, and don’t get a bad rash from exposure. But it’s best to learn how to recognize the plant and avoid it, experts say.

This article is for informational purposes only, and is not meant to offer medical advice.

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Can Poison Oak Leave Scars?

As poison ivy creeps up in the central and eastern U.S., poison oak is the bane of many an outdoor traveler or worker on the West Coast. Extremely common in some places, poison oak also comes in a diversity of growth forms, and its foliage easily blends in with brushy surroundings. Normally, the irritating allergic effect provoked by contact with poison oak in most people does not create permanent scars.

Poison Oak

Poison oak, or Toxicodendron diversilobum, is a common shrub or vine on the West Coast, growing from British Columbia to Baja, California. Its common name stems from the soft-lobed leaves that bear strong superficial resemblance to the foliage of white oaks –- and suggests the affinity poison oak shows for these trees, often growing tangled along their trunks or in their shade. The plant is deciduous; the leaves turn a rich crimson-burgundy in autumn before falling.

Contact Dermatitis

Most people are allergic to an oleoresin that poison oak and other members of the Toxicodendron genus called urusiol possess. Merely brushing the stems or leaves of a poison oak plant can provoke its secretion. While symptoms vary, most people develop a rash — frequently in linear flushes — within several days. The inflammation is exceedingly itchy, and scratching can exacerbate the blistering typically accompanying the rash. Individuals with more severe allergies may experience pronounced swelling, enough to force shut eyes or puff up a face, or widespread blistering, in which case they should seek medical attention. The rash eventually subsides over a week or two.


In most cases, rashes caused by poison oak do not leave lingering marks like scars as the redness clears up as the allergic response concludes. However, if blisters or sores are not kept clean and become infected, more serious effects may result — like abscessing and fever –, and in such cases, permanent scarring is possible.


Folk remedies for poison oak, poison ivy and the other Toxicodendron rogue’s gallery are legion, as are modern chemical products on the shelf 2. The main key to treatment is quickly — immediately, if possible — removing the offending urusiol oil. This may be done with cold water and gentle soap, or with specialized substances like Tecnu, an over-the-counter treatment. The effectiveness of washing decreases quickly over time, but still helps to restrict the spread of the oil. A good approach is to wash thoroughly any part of your body and anything else that may have been exposed to poison oak if you’ve been out in an area replete with the plants, even if you don’t see a rash.


To avoid poison oak, learn to recognize all its seasonal appearances: as a hard, rigid stalk during winter; bearing crimson leaves of spring or autumn growth; and in deep-summer glossy green. Recognize, too, its preferred habitat. In the Pacific Northwest, it tends to grow in drier, sun-sprayed lowlands, avoiding cool, dark mountain forests. In California, it is ubiquitous in many brushy hills, oak savannas and chaparral. Stick to trails where possible and, if working off-trail, avoid loose-fitting clothing and much dangling gear.

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