Poison ivy rash is caused by contact with poison ivy, a plant that grows almost everywhere in the United States. The sap of the poison ivy plant, also known as Toxicodendron radicans, contains an oil called urushiol. This is the irritant that causes an allergic reaction and rash.

You don’t even have to come in direct contact with the plant to have a reaction. The oil can linger on your gardening equipment, golf clubs, or even your shoes. Brushing against the plant — or anything that’s touched it — can result in skin irritation, pain, and itching.

Here’s how to spot the danger, and what you can do if poison ivy gets too close.

The allergic reaction caused by poison ivy is known as contact dermatitis. It happens when your skin comes into contact with an irritant, such as urushiol.

Poison ivy exposure can result in thin red lines on the skin when you’ve brushed against the edge of the leaves directly. If you touch pets that have the oil on their fur or touch clippings when emptying the mower bag, the rash can cover a larger area.

Classic symptoms that you’ve come into contact with poison ivy include:

The rash may begin appearing within 12 hours; it can take a few days to fully develop. Its severity depends on how much urushiol you get on your skin.

If you know you touched poison ivy leaves, you won’t need to see a doctor for an official diagnosis. If you do decide to visit your doctor, they can diagnose a poison ivy rash by looking at your skin. No other tests, such as a biopsy, will be needed.

Your doctor may order tests to help identify the cause of your symptoms if they’re not sure poison ivy caused the rash. Several common skin issues can cause red, itchy rashes.

For example, a common skin condition called psoriasis can be confused with a poison ivy rash. Psoriasis can cause a red rash with whitish-silver scales. This rash can be itchy, and it may even crack and bleed.

Psoriasis, unlike a poison ivy rash, will likely come back after it disappears. That’s because psoriasis is a chronic autoimmune disorder. Learn how to tell the difference between the two conditions so you can decide which you may be experiencing.

If you’ve gotten a rash despite your best efforts to avoid the plant, there are things you can do. You can usually treat the rash yourself at home. Poison ivy doesn’t have a cure, but even left untreated, it will eventually clear on its own within two to three weeks.

However, you should go to the emergency room for urgent medical care if:

Most cases of poison ivy don’t need to be treated by a doctor. Widespread poison ivy rashes may require treatment with a prescription corticosteroid. Rarely, you can also develop a bacterial infection at the rash site. If this happens, you may need a prescription antibiotic.

If you’ve come into contact with poison ivy, here’s what to do:

Wash your skin and clothes

Immediately wash any areas of your skin that might have touched the plant. This may help remove some of the oil and lessen the severity of your reaction.

Also, be sure to wash the clothes you were wearing, along with anything that may have touched the plant. Although the rash can’t spread, the oil that caused it can.

Take an antihistamine

Taking an over-the-counter (OTC) antihistamine can help relieve itching and allow you to sleep more comfortably.

Apply drying lotion

Apply calamine lotion or hydrocortisone cream topically to stop the itching.

Don’t scratch

Scratching the rash will only make things worse. While it may bring immediate comfort, scratching will only prolong symptoms. You may even develop an infection if you break the skin, causing itching to intensify.

Soothe your skin

Take frequent warm baths in water containing an oatmeal product or apply cool, wet compresses to help relieve the itch.

Some home remedies can help reduce irritation and itching while the rash is healing. These include:

Menthol cream

Organic compounds from peppermint have a cooling effect on irritated skin. You can buy OTC products with this ingredient, or you can make your own with peppermint essential oils.

Be sure to dilute the essential oil in a lotion or oil so it does not irritate the sensitive skin.

Several other essential oils, including calendula, chamomile, and eucalyptus may be helpful for reducing symptoms of poison ivy rash. Learn more about these oils and how to use them on irritated skin.

Aloe vera

The soothing burn treatment can also relieve itching and inflammation in skin affected by a poison ivy rash.

Colloidal oatmeal

Oatmeal baths are a popular home treatment for skin rashes and conditions. The finely ground oats can coat the skin and relieve itching temporarily.

Witch hazel

A liquid product of the Hamamelis virginiana plant, witch hazel may ease itching, swelling, and burning on irritated skin.

Apple cider vinegar

Apple cider vinegar is a popular alternative poison ivy treatment. Research isn’t clear why it helps, but anecdotal evidence suggests the vinegar solution helps dry up urushiol, which can speed healing.

No, poison ivy is not contagious. It cannot spread from person to person.

It can, however, be spread in a few other scenarios. For example, a pet that encounters poison ivy leaves can carry the urushiol oil in its fur. When you touch the animal, you may pick up the oil and develop a rash.

Clothing fibers can also spread poison ivy’s oil.

If you touch poison ivy with a pair of pants or shirt and do not wash it after contact is made, you could develop another rash if you touch the clothing. You can also spread the oil to another person, if they come into contact with clothes that have touched poison ivy.

A poison ivy rash cannot spread across your body either.

You may notice, however, that the rash develops over the course of several days. Poison ivy rashes can grow slowly, which may give the appearance of spreading. But a rash will only occur on areas of the skin that came into contact with the urushiol oil.

If you get a poison ivy rash after the initial exposure, consider everything you’ve touched that may carry the oil. Learn more about what these objects could be and what you can do to avoid sharing the oil with yourself or others again.

About 85 percent of Americans are allergic to poison ivy. These people will experience mild, but irritating, symptoms, such as a red rash, itching, and swelling. Of those who are allergic, about 10 to 15 percent will have a severe reaction. They may develop fluid-filled blisters that become infected.

Infants and toddlers can also develop a poison ivy rash. It may take several hours or days for the rash to fully develop. In severe cases, the child may also develop blisters.

The only way to know if you’re allergic to poison ivy is to touch it, which isn’t recommended. Instead, try learning what poison ivy looks like. This way you can work to avoid contact.

As with many other perennial plants, poison ivy changes with the seasons. The leaves of the poison ivy plant are green in the summer, but can turn red, orange, or yellow in the spring and fall.

The plant may flower with greenish-yellow blossoms and produce small, green berries that turn white in the fall.

Unfortunately, poison ivy can spread urushiol to skin in all seasons. Even in winter, when the leaves are gone, you can come into contact with the plant’s berries or aerial roots and pick up some of the sticky oil.

Older poison ivy shrubs or vines develop thin, hair-like roots above ground. These are the aerial roots, and they help identify the plant when the leaves have all fallen away for winter.

Poison ivy is native to every state except California, Alaska, and Hawaii and can be found in Central America, Mexico, and Canada as well. It’s been introduced to countries in Central America, Asia, and Europe and is found in Australia and New Zealand too. So, there’s a pretty good chance you’ll eventually cross paths with it.

Tips for identifying poison ivy

Learning how to identify poison ivy may help you avoid this highly irritating plant.

Poison ivy grows as a shrub in the northern and western United States.

The most commonly found type of poison ivy is known as western poison ivy. This type can grow to be anywhere from 6 to 30 inches tall. A second type, known as eastern poison ivy, grows as a trailing vine along the ground or clinging to trees in the East, Midwest, and South.

For both western and eastern poison ivy, the leaves are made up of three-pointed leaf clusters that have a glossy surface. This is where the old saying, “Leaves of three, let it be,” comes from. The edge of the leaflets can be toothed or smooth.

While certainly uncomfortable and irritating, a poison ivy rash doesn’t pose a serious risk to a pregnant woman or a developing baby.

Typical home remedies, including colloid oatmeal baths and topical anti-itch medicines are safe for pregnant women to use. However, it’s a good idea to talk with a doctor before taking any medications like Benadryl.

If you have any serious reactions during pregnancy, seek treatment right away and consult with your obstetrician as well.

Most Americans are allergic to poison ivy. More than 4 in 5 people will develop an itchy, red, swollen skin rash when they come into contact with poison ivy and its urushiol oil.

Of the people who are allergic to poison ivy, a smaller group are hypersensitive to the plant. These individuals are more likely to develop a severe reaction. About 10 to 15 percent of people with an allergy to poison ivy fall into this severe category.

A severe poison ivy allergy causes:

People with a severe poison ivy allergy should see their doctor as soon as a rash begins to develop. Treatments, including corticosteroids and antibiotics, may help reduce the severity of symptoms.

A poison ivy rash is bothersome. The itching and swelling can be irritating. Rarely, a poison ivy rash can be serious or fatal. When this happens, it’s often the result of complications caused by the reaction.

Complications of a poison ivy rash include:

Infection

A bacterial infection is a common complication of a poison ivy rash. Repeated scratching can cause microscopic breaks in the skin. Bacteria can make their way into the breaks, and an infection can develop. You will need antibiotics to treat this.

Poison ivy in the lungs

If you come into contact with poison ivy that is burning, you may inhale plant compounds. This can lead to irritation in the lungs, airways, and eyes.

Spreading

A poison ivy rash will only develop on skin that comes into contact with the plant’s oils. However, you can transfer the oil to other parts of your body if urushiol remains on your hands.

Also, the oil can remain on items like a pet’s fur, clothing, gardening utensils, and recreational equipment. If these items are not properly washed, you can pick up the oil again later, causing another rash.

Death

If you begin experiencing breathing or swallowing difficulties after coming into contact with poison ivy, seek treatment right away. This is an emergency situation that could become deadly without proper treatment.

An allergic reaction occurs when the oil comes in contact with your skin. Knowing what to look for is only part of the equation when it comes to avoiding the rash. The key is to prevent contact.

Prepare yourself before venturing into places where you might find the plant. This means covering your skin before gardening or doing other outdoor activities. You should also wear eye protection while mowing.

If you can’t cover your body completely, use an ivy blocking cream. There are several varieties that protect your skin from absorbing urushiol. They usually contain an ingredient called bentoquatam.

Apply it before going outdoors. Pack a supply of ivy blocking cream to take along with you if you’re hiking or camping.

Carefully clean items that have touched poison ivy to prevent exposure later. Gardening tools, sporting equipment, and camping supplies can all harbor urushiol.

A little prevention can go a long way. If you take precautions, you may never discover how uncomfortable the rash can be.