Poison Ivy, Part 2

by Food and Drug Administration (FDA)

(Page 2 of 2)

The rash will only occur where urushiol has touched the skin; it doesn't spread throughout the body. However, the rash may seem to spread if it appears over time instead of all at once. This is either because the urushiol is absorbed at different rates in different parts of the body or because of repeated exposure to contaminated objects or urushiol trapped under the fingernails.

The rash, blisters and itch normally disappear in 14 to 20 days without any treatment. But few can handle the itch without some relief. For mild cases, wet compresses or soaking in cool water may be effective. Oral antihistamines can also relieve itching.

FDA also considers over-the-counter topical corticosteroids (commonly called hydrocortisones under brand names such as Cortaid and Lanacort) safe and effective for temporary relief of itching associated with poison ivy.

For severe cases, prescription topical corticosteroid drugs can halt the reaction, but only if treatment begins within a few hours of exposure. "After the blisters form, the [topical] steroid isn't going to do much," says Epstein. The American Academy of Dermatology recommends that people who have had severe reactions in the past should contact a dermatologist as soon as possible after a new exposure.

Severe reactions can be treated with prescription oral corticosteroids. Phillip M. Williford, M.D., assistant professor of dermatology, Wake Forest University, prescribes oral corticosteroids if the rash is on the face, genitals, or covers more than 30 percent of the body. The drug must be taken for at least 14 days, and preferably over a three-week period, says FDA's Ko. Shorter courses of treatment, he warns, will cause a rebound with an even more severe rash.

There are a number of OTC products to help dry up the oozing blisters, including:

• aluminum acetate (Burrows solution)
• baking soda
• Aveeno (oatmeal bath)
• aluminum hydroxide gel
• calamine
• kaolin
• zinc acetate
• zinc carbonate
• zinc oxide

Desensitization, vaccines, and barrier creams have been studied over the last several decades for their potential to protect against poison ivy reactions, but none have been approved by FDA for this purpose.

Right now, prevention seems the best treatment, unless you plan to take lessons from Batman's bane with Poison Ivy's name.

Getting Rid of the Plants

Poison ivy, oak and sumac are most dangerous in the spring and summer, when there is plenty of sap, the urushiol content is high, and the plants are easily bruised. However, the danger doesn't disappear over the winter. Dormant plants can still cause reactions, and cases have been reported in people who used the twigs of the plant for firewood or the vines for Christmas wreaths. Even dead plants can cause a reaction, because urushiol remains active for several years after the plant dies.

If poison ivy invades your yard, "there's really no good news for you," says David Yost, a horticulturist (specialist in fruits, vegetables, flowers, and general gardening) with the state of Virginia. The two herbicides most commonly used for poison ivy — Roundup and Ortho Poison Ivy Killer — will kill other plants as well. Spraying Roundup (active ingredient glyphosate) on the foliage of young plants will kill the poison ivy, but if the poison ivy vine is growing up your prize rhododendron or azalea, for example, the Roundup will kill them too, he says.

Ortho Poison Ivy Killer (active ingredient triclopyr), if used sparingly, will kill poison ivy but not trees it grows around, says Joseph Neal, Ph.D., associate professor of weed science, Cornell University. "But don't use it around shrubs, broadleaf ground cover, or herbaceous garden plants," he says. Neal explains it is possible to spray the poison ivy without killing other plants if you pull the poison ivy vines away from the desirable plants and wipe the ivy foliage with the herbicide, or use a shield on the sprayer to direct the chemical.

If you don't want to use chemicals, "manual removal will get rid of the ivy if you're diligent," says Neal. You must get every bit of the plant — leaves, vines, and roots — or it will sprout again.

The plants should be thrown away according to your municipality's regulations, says Neal. Although urushiol will break down with composting, Neal doesn't recommend that because the plants must be chopped into small pieces first, which just adds to the time you're exposed to the plant and risk of a rash. "It's a health issue," he says.

Never burn the plants. The urushiol can spread in the smoke and cause serious lung irritation.

The American Academy of Dermatology recommends that whenever you're going to be around poison ivy — trying to clear it from your yard or hiking in the woods — you wear long pants and long sleeves and, if possible, gloves and boots.

Neal recommends wearing plastic gloves over cotton gloves when pulling the plants. Plastic alone isn't enough because the plastic rips, and cotton alone won't work because after a while the urushiol will soak through.

Identification Please

Unfortunately, poison ivy, oak and sumac don't grow with little picture ID badges around their stems, so you have to know what to look for. The famous rule "leaves of three, let it be" is good to follow, except that some of the plants don't always play by the rules and have leaves in groups of five to nine. To avoid these plants and their itchy consequences, here's what to look for.

Poison Ivy

• grows around lakes and streams in the Midwest and the East
• woody, ropelike vine, a trailing shrub on the ground, or a free-standing shrub
• normally three leaflets (groups of leaves all on the same small stem coming off the larger main stem), but may vary from groups of three to nine
• leaves are green in the summer and red in the fall
• yellow or green flowers and white berries

Poison Oak

• eastern (from New Jersey to Texas) grows as a low shrub; western (along the Pacific coast) grows to 6-foot-tall clumps or vines up to 30 feet long
• oak-like leaves, usually in clusters of three
• clusters of yellow berries

Poison Sumac

• grows in boggy areas, especially in the Southeast
• rangy shrub up to 15 feet tall
• seven to 13 smooth-edged leaflets
• glossy pale yellow or cream-colored berries

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.