Dealing with Poison Ivy

poison ivy plantAnyone 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.

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.poison ivy - spring growth

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.

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.

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, 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 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 reexposure.

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.

Edmond L. Marrotte, former Consumer Horticulturist at UConn’s Home and Garden Education Center, recommends Glyphosate as a control for poison ivy. (Some of the brand names of Glyphosate are Rounduptm and Kleenuptm.) Glyphosate should be applied as a 1½ to 2 % solution to the foliage in late August to October. Marrotte said it is not necessary to get the whole plant. Leaves can also be selectively "painted" with the solution using a disposable brush or cotton rag.

Read the herbicide label to make sure that poison ivy is listed on the label. Do not use herbicides in windy conditions. They could blow onto landscape plants or the applier. Use gloves approved for use with garden chemicals and avoid getting herbicide on the skin and in eyes.

Confine Glyphosate to weeds and avoid letting it or the spray drift contact any cultivated plants. It can damage or kill all plants. Repeated applications may be necessary.

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 this web page Fact Sheet with photos and a discussion of poison ivy.

The Publications Resource Center store has a free Horticulture Fact Sheet posted on their site. ( Look for Poison Ivy – Toxicodendron radicans (No. 60). It is also available on the UConn IPM website or by calling (860) 486-3336 or stopping by the store at the W.B. Young Building, Room 2 on the Storrs campus. Business hours are 8 AM to 4:30 PM.

News Alert-Hogweed

Recent Connecticut media reports have discussed Giant Hogweed (Heracleum mantegazzianum), another poisonous plant that can cause health problems like skin blisters, rashes, burns and scarring. Giant hogweed is an invasive, non-native plant first confirmed in the State in 2001. Giant Hogweed has been found in nine towns in Connecticut to date.

An Extension Educator with the College of Agriculture and Natural Resources, Donna Ellis, and other members of the Connecticut Invasive Plant Working Group (CIPWG) are alerting the public about this weed. Readers can see photos and learn about giant hogweed on the Connecticut Invasive Plant Working Group website . Ellis, co-chair of the group, said the web site will be updated as new information becomes available.

Patsy Evans, Writer/Editor, CANR Resources, Communications and Information Technology,
October 2002

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.

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