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Integrated Pest Management Program

Department of Plant Science and Landscape Architecture, Department of Extension

Fact Sheets > Turf Landscape > Weeds

Dealing with Poison Ivy

Anyone who has a brush with poison ivy may be tempted to buy an ocean of calamine lotion. An allergic reaction to poison ivy can be uncomfortable, to say the least. According to estimates, about 70 percent of people are sensitive to it. Here are some tips on dealing with the plant.

Appearance

The best way to avoid that itchy feeling you get from a poison ivy rash is to avoid contact with the plant. The best way to avoid the plant entirely is to know what poison ivy looks like.

Poison ivy (Toxicodendron radicans) is an adaptable, woody perennial weed that forms vines. The way it grows and looks and its location may vary. Some plants may carpet the ground while others climb tree trunks, stone walls, fences, and posts. The edges of the leaflets may be lobed, smooth or toothed. Poison ivy grows in the open, in deep shade, or along path and road edges. When it grows among other vines, it is more difficult to recognize.

Poison ivy plants have a compound leaf arrangement made up of three leaflets on a leafstalk. Two leaflets grow on opposing sides and the third stands by itself at the end of the stalk. Poison ivy leaflets sometimes have hairy undersides. Its stems are woody. The aerial rootlets make the stem look like a fuzzy rope. 

Each season, poison ivy has a slightly different color and appearance. New springtime growth is often reddish and especially shiny. After the leaves emerge, the plants may develop a cluster of greenish flowers. Poison ivy fruit has a white, waxy appearance, a smooth surface and looks like mistletoe. Summertime foliage is either dull or glossy green. Fall foliage can be yellow, red or orange.

Dissemination

Poison ivy is persistent. Birds can eat the fruit and drop seeds, which germinate easily. In addition, the plant is spread by creeping rootstocks that extend from the parent plant. New plants can sprout from a small, buried root section that escapes cultural control attempts.

Allergen

Poison ivy leaves, stems, fruit, flowers, and roots contain a toxic substance called urushiol. It is released onto the plant surfaces when poison ivy is bruised or damaged. If a sensitive person’s skin touches such a plant, an allergic reaction can result. In addition, poison ivy can contaminate people indirectly when they touch clothing, garden tools, or pets, which came in contact with the poison ivy, or inhale the smoke from a burning plant. The oil remains potent for a couple of weeks, longer in very dry conditions.

Urushiol is present in all plants in the Anacardiaceae family, at all times of the year, in about the same strength. However, it is easiest to get allergic contact dermatitis from poison ivy in the spring or early summer when leaves are tender and easily bruised.

Even a small amount of urushiol can cause a severe reaction in some people. How much oil gets on the skin, the sensitivity of the person who contacted the poison ivy and how quickly it is washed off may affect the severity of the symptoms. Thicker skin, such as that on the palms, is less susceptible than the thin skin on the face. Hairy and/or dark color skin is more resistant. A person is more susceptible to an allergic reaction when they are sweating because the pores of the skin are wide open and easily absorb the urushiol. According to Karl Hempel, a medical doctor in Florida, children become susceptible by age 3 and are highly susceptible by age 12.

Not everyone has an allergic reaction the first time he or she comes in contact with the plant. The body does develop an immune response on first contact that builds each time a person is exposed. Usually, repeated exposures result in increasingly severe reactions. A few people appear to be immune but, in fact, may react only to large amounts of urushiol.

Symptoms

Symptoms usually appear hours to several days after exposure. The skin itches intensely and may burn and swell. A rash with watery blisters develops. The rash may appear in streaks. Sometimes a secondary infection may develop in the open lesions.

A person who touches the actual rash or the fluid in the blisters cannot contract poison ivy. It will not spread from one part of the body to another that way. However, urushiol that remains on the skin or clothing, or on your pet’s fur, can be transferred to another person, which may result in a rash. Urushiol may be transferred from one unwashed spot to a different body part, which results in re-exposure.

Treatment

Wash the oil off exposed skin and under the fingernails with plenty of soap and water. Speed is important. “As little as ten minutes of exposure may produce the allergic reaction,” Dr. Hempel said.

Washing with cold water is best because hot water opens the skin pores and aids in absorption of the oil. An alkaline soap is supposed to be more effective than a pH-neutral soap in breaking down the toxin.

For minor cases, an over-the-counter lotion or cream may ease the itching and dry up the blisters with limited success. Oatmeal or cornstarch baths and cold compresses are soothing. An over-the-counter antihistamine or anti-inflammatory can lessen the discomfort. Total healing may take a week or two.

Severe cases of allergic reactions to poison ivy require a doctor’s attention. Watch for fever, headache, widespread rashes and swelling or signs of infection. A doctor may prescribe oral, topical or injected steroids for serious cases. If the patient experienced severe cases in the past, he/she should consult with a doctor right after a known exposure to poison ivy.

My research failed to show any scientific studies of over-the-counter products that claim to prevent people from getting a rash once they are exposed to urushiol. However, the Food and Drug Administration approved bentoquatam 5%, which is available without a prescription. It provides a protection barrier when applied at least 15 minutes before exposure and reapplied every four hours. It should not be used if the individual already has a rash from the plant. Bentoquatam 5% is contained in a lotion and manufactured under the trade name, Ivy Block.

A superstitious story recommends eating poison ivy or rubbing it on the skin as a sort of immunization. Such a practice is not advised; it could result in a fatal reaction.

Weed Control

Control poison ivy culturally, biologically or chemically. Cultural methods, which may not be very appealing, include constantly mowing or cutting young shoots until the plants die. Vines that are climbing trees may be cut and pulled away from the trees. When the soil is wet, the roots can be dug up and pulled out of the soil. Any root sections left in the ground can sprout. Therefore, the whole plant must be removed to make the eradication effective. Dispose of plants where they cannot contaminate people or animals.

Remember the plant can be toxic at any time of the year. Cover as much skin as possible with protective gloves and clothing, such as rubber gloves, long pants, socks and shoes and a long-sleeved shirt. These items and tools that have come in contact with poison ivy must be cleaned to prevent the spread of urushiol. Clothes should be laundered in a washing machine with detergent.

Sheep and goats will eat poison ivy. They can be tied in the area of poison ivy infestation. Local laws and the neighbors’ disapproval may prohibit such a practice.

Do not destroy poison ivy with fire. When a poison ivy plant is burned, poisonous particles go into the air on the smoke. They can produce an allergic reaction in the eyes and respiratory tract or on the skin. Note: Be careful not to burn wood that has poison ivy vines, in your woodstove or fireplace.

For control of poison ivy, contact your local Cooperative Extension Center.

Summary

Learn to recognize poison ivy. Always avoid it. Wear protective clothing when you are in areas where it is present. Keep pets away from the plants. If you have a brush with poison ivy accidentally, wash it off right away. If you resort to chemical weed control, apply it from late August to October for best effectiveness. However, do not stockpile oceans of calamine lotion to treat the rash. As my own doctor said, “The pink stuff is no good.” Try other products for better relief.

More Information

The Home and Garden Education Center, at the University of Connecticut College of Agriculture and Natural Resources, posted a poison ivy Fact Sheet with photos and a discussion of poison ivy.

Patsy Evans, Publicity/Marketing Administrator, CANR Office of Communications, Patsy.Evans@uconn.edu

Updated: Patsy Evans, 2012

References

Hamilton, G. Let it Be, Poison Ivy!  2001.

Hempel, K. Health Gazette. August 7, 2002.

Kemper Center for Home Gardening, Missouri Botanical Garden. Poison Ivy.  August 19, 2002.

Marrotte, E.L. Personal communication. July 2002.

Information on our site was developed for conditions in the Northeast. Use in other geographical areas may be inappropriate.

The information in this document is for educational purposes only.  The recommendations contained are based on the best available knowledge at the time of publication.  Any reference to commercial products, trade or brand names is for information only, and no endorsement or approval is intended. The Cooperative Extension System does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available.  The University of Connecticut, Cooperative Extension System, College of Agriculture and Natural Resources is an equal opportunity program provider and employer.