Poison-ivy season is upon us, and the scourge of summer is shaping up for one of its most virulent and unpredictable seasons. Public gardening advisers in many regions of the country say poison-ivy complaints this year are more plentiful than in recent memory.
Campers, highway crews, kids chasing baseballs into the weeds - all are at risk for an encounter with /Toxicodendron radicans/. "I think people are spending more time landscaping, growing vegetables and just being in their yards more," says Bob Ary, an agent with the University of Tennessee extension in Sumner County, who estimates poison-ivy queries from backyard gardeners are up about a third over last year. "There are some plants that look pretty similar to poison ivy, and inexperienced gardeners sometimes don't know how to tell the difference."
Exact numbers on poison ivy's rise are hard to pin down, because so many cases go unreported. More than 350,000 people each year suffer from poison ivy, according to a 2006 study published in the Proceedings of the National Academy of Sciences. Other estimates go higher, especially if taking poison ivy's toxic cousins, poison sumac and Western poison oak, into account.
 Poison Ivy |
 Poison Oak |
 Poison Sumac |
They all produce urushiol, a skin-irritating oil that combines with skin proteins to trigger the tell-tale allergic reaction---an angry red rash that itches badly enough to make a person miss a day or more of work or fun.
About 15% of the population is insensitive to urushiol and will never develop a reaction. For everyone else, repeated exposure tends to make the rash worse. "The dermatitis gets worse each subsequent time," says Dawn Davis, a dermatologist at Mayo Clinic in Rochester, Minn. On the other hand, a person's sensitivity tends to decline with age.
There's no shortage of theories on why poison ivy seems to be rising. Some veteran gardeners think the particularly brutal winter in many regions killed off many prized perennials and shrubs---leaving more room for weeds to flourish. Another theory: more novice gardeners are zealously digging out weeds to plant vegetable patches and making contact with poison ivy.
A study, published in the journal Weed Science in 2007, suggested that poison ivy is getting bigger, spreading faster and producing more urushiol as the result of increasing levels of carbon dioxide in the atmosphere. Lewis Ziska, a plant physiologist at the U.S. Agriculture Department who led the study, exposed poison ivy plants to different carbon dioxide concentrations---mirroring those that actually existed in the atmosphere at various times over several decades. The increased exposure levels produced bigger, hardier, and more irritating plants.
Poison ivy makes for an unpredictable allergen that has no comfort zone. Geralyn Caplan, an Evansville, Ind., biology teacher, says through many years of camping as a child, she never caught poison ivy. But in each of the past three years, she says, "I got nailed with it." She has been spending more time out in the yard clearing flower beds now that her kids are grown. She recently recovered from her worst case ever, when rashes and welts spread on her arms and legs.
"You might not be sensitive to it your whole life," says Dan Brown, a professor of animal nutrition and toxicology at Cornell University. "And then, Bingo."
After exposure, there is typically a 15- to 30-minute window in which you can avoid a reaction, by washing the urushiol off the skin. Several over-the-counter products can be used in this critical window and beyond, including Zanfel, a soapy wash that sells in a one-ounce tube for $39.99. Sales so far this year are running 10% to 12% ahead of the same period last year, says Steve Sisler, vice president of sales at Zanfel Laboratories Inc., of Clive, Iowa. "The season this year is moving appreciably faster than last year," he says. Washing with regular soap and warm water works, too, if done soon enough.
Prevention costs less than the cure: IvyBlock lotion, manufactured by Hyland's Inc., Los Angeles, claims to work like sun block, with a patented ingredient that absorbs urushiol before it can irritate the skin. The company says it has Food and Drug Administration approval to help prevent poison ivy, oak and sumac rashes; it retails for $12.99 for four ounces. Physicians stress the usefulness of socks and long sleeves.
If a rash develops---in most cases 12 to 72 hours after exposure---dermatologists say the first step is to try treating it at home (see "Itch Alternatives" on home remedies). An over-the-counter topical cortisone ointment, like Cortizone-10, can reduce the inflammation, and an antihistamine, like Benadryl, can relieve the itch.
If that doesn't bring relief, a doctor may prescribe cortisone injections or pills. "People can have extensive blistering in large areas of the body if they have enough contact,"says Joseph Fowler, a clinical professor of dermatology at the University of Louisville School of Medicine. "You can get blisters to the point of being oozy and itchy."
A very bad scenario would be to clear poison ivy from your yard and burn it in a campfire, since it is possible to develop respiratory inflammation from breathing urushiol-laced smoke.
Recognizing poison ivy isn't easy. It can grow as a ground cover, a vine or a small bush. The leaves grow in clusters of three---hence the adage, "Leaves of three, let it be"---but the leaves can be smooth or toothed, in which case identification becomes more difficult. Western poison oak leaves are deeply cut and resemble those of a true oak tree. Poison sumac's signature is its red stems.
Poison sumac is typically found in swampy areas, especially in the South. Western poison oak is common along the Pacific coast. Poison ivy typically grows east of the Rockies, although recent reports suggest it may be spreading to places where it didn't previously thrive.
One of poison ivy's quirks is that many animals can touch or even eat it with no ill effects. "Animals not only eat it, they love it," says Jacqueline Mohan, a professor of ecology at the University of Georgia and co-author of the 2007 Weed Science study.
Pets play an important role in the spread of poison ivy. A dog with urushiol on its fur will pass it along to friendly humans who pat or rub those places.
The same sort of thing happens with camping equipment. Denis Sasseville, director of the dermatology division at McGill University, in Montreal, recalls a patient who came in every week with a new poison ivy reaction. He repeatedly told the patient to stay out of the bushes and kept showing him photos so he would know what poison ivy looked like. It didn't help. It turned out the patient, who was camping, had a sleeping bag, chairs and a tent pole covered with urushiol.
The lesson, Dr. Sasseville says: "Everything needs to be washed, because the sap stays allergenic forever."
In Junction, City, Kan., the Geary County Extension service, affiliated with Kansas State University, says poison-ivy queries to its office were up by a third last year and are running at about that same level this year. Poison-ivy calls to the Cornell University Cooperative Extension in Voorheesville, N.Y., have doubled in the past five years, says Susan Pezzolla, community educator for horticulture. "I think it's getting more prevalent," says Randy Roloff, road supervisor for Outagamie County in northeast Wisconsin. "It's spreading and tough to kill."
"Business is good," says Umar Mycka, who started a landscaping company three years ago devoted entirely to poison-ivy removal. Based in Philadelphia, he has customers from Maryland to New Jersey. "I call our method hand-to-vine combat," he says. "We get down on our hands and knees and find them, search them down to the ground and dig them up."
And then there are those people who actually like poison ivy. It's a native of North America, and its berries are an important source of food for wildlife. That explains why there are few concerted efforts to eradicate it. "We keep it out of the garden beds but let it grow elsewhere," says Eleanor Cone, a retired photography teacher in Forest Hill, Md. "One reason we garden is to create and maintain a habitat for wildlife."
Write to Anne Marie Chaker at anne-marie.chaker@wsj.com and Anjali Athavaley at anjali.athavaley@wsj.com
Itch Alternatives: A Look at Home Remedies
A regular victim of botanical abuse, WSJ's "About the House" columnist Wendy Bounds discusses home remedies for poison ivy. Dishwashing detergent, cleaning solution with jewelweed, baking soda, oatmeal, teabags, buttermilk compresses, bleach, banana peals, watermelon rind, are some of the home remedies that Wendy says might be worth a try.
Itch Relief
A recent nasty case of poison ivy left me hunched over the laptop, searching—between scratching—for relief from the ugly, weepy mess. There, I discovered people swear by almost every kind of home remedy imaginable, from banana peels and watermelon rinds to bleach and gasoline.
What's the science behind the relief? And can some techniques (Clorox compresses?) do more harm than good?
Some doctors discourage kitchen-cupboard remedies, but others say many can be safe complements to traditional medical treatment. Here's the take of three physicians: Tim Berger, vice chairman of the dermatology department at the University of California at San Francisco; Maya Jerath, an allergist with the allergy and immunology clinic at the UNC Health Care System, in Chapel Hill, N.C., and Alan Dattner, a New York holistic dermatologist.
| Acorns | Some poison ivy sufferers boil cracked acorns in water, strain and cool the remaining liquid, and then apply to affected area. This may have a soothing, drying effect due to tannins, which are astringent, Dr. Dattner says. |
| Rubbing alcohol | It can work as a solvent to strip the oily allergen urushiol off skin. Best used immediately after contact. "It's like putting wine into your vinaigrette, which then dissolves the oil as you shake it," Dr. Berger says. It may provide cooling, to reduce itching, or antiseptic qualities. |
| Baking soda | It makes a soothing compress to help with inflammation. Sodium bicarbonate may pull the fluid out of blisters and help dry them. |
| Bleach | Diluted, it can help dry blisters and keep crusting and infection at bay. Dr. Berger's recommended dosage: half a cup in a full bathtub for soaking or a teaspoon in a pint of water for a compress. Dr. Dattner warns about possible negative reaction in places unaffected by poison ivy. |
| Buttermilk | Unless you are allergic to milk, this remedy's proteins may help by drawing out blister fluids. Yogurt, likewise, is sometimes used for a soothing element. |
| Dishwashing detergent, Jewelweed and Clay soaps |
Liquid dish soap, designed to cut grease and remove food oils on dishes, can do the same thing on skin. Some herbalists use the jewelweed plant to remove poison ivy oil or as a salve to reduce itch. Clay may help dry up weeping blisters. |
| Gasoline | Like rubbing alcohol, gasoline is an organic solvent that may dissolve urushiol on skin immediately after contact. It also may knock out the superficial nerves that cause you to feel the itch. None of the doctors, however, recommends this remedy because of its potential toxicity—and the "risk of catching fire," notes Dr. Jerath. An exception: extreme emergencies "like camping, where that's all you've got," Dr. Berger says. |
| Oatmeal | Known to be soothing in a bath or a compress, this is "one of the most harmless" treatments to try, Dr. Jerath says. It's a staple of some over-the-counter treatments. Like baking soda, it may help draw out serum in blisters, dry sores and soothe inflammation. |
| Tea bags | A bathtub filled with water and a dozen or so teabags might help dry blisters. Drs. Berger and Dattner note that teas such as chamomile may have anti-inflammatory properties. |
| Vinegar | Not harmful if diluted—but not a lot of sense behind this one, doctors agree. It may help ward off some bacterial infection; Dr. Dattner says some people's itching ebbs on contact from acidic liquids. "But it's going to sting," he warns. |
| Watermelon rind, Banana peel |
Watermelon rind may act as a cold compress, with the water content helping to dry out blisters. Neither doctor could guess why banana peel shows up on so many websites as a "miracle" cure "It's wet and gooey and a compress," Dr. Rattner guesses. |