An Itchy Nuisance for 85% of Americans

Poison ivy, poison oak, and poison sumac can ruin your summer. For many, direct content with this foul foliage triggers an immune response in the body resulting in blisters, burning, redness and swelling. Sensitivity to an oily sap called urushiol (u-ROO-she-ol) causes this reaction. The leaves, stems and roots of poison ivy, poison oak and poison sumac all carry this oil.

Urushiol packs a punch: According to the CDC, an amount equal to a grain of table salt can trigger the allergic reaction and cause a rash!

poison ivy

Credit: Paul Lowry via Flickr

Of all the plants that carry urushiol, the most common is poison ivy. Eastern and Western varieties of this hardy native plant can be found in virtually every state within the continental U.S. Poison ivy isn’t picky when it comes to setting up shop – it’s found on the edges of forests and fields, by the sides of highways, and often finds its way into neighborhood parks and backyards in cities and towns across the U.S. 


Eastern Poison Ivy States

poison ivy

Western Poison Ivy States

And while its leaves, berries and vines are toxic to humans, birds, bear and deer can munch on the plant with no ill effects. In contrast, about 85% of people are allergic to poison ivy.

How to Treat the Itch

  • Minor cases can treated with over-the-counter topical creams, of which Calamine lotion is perhaps the most famous.
  • If you’re allergic, consider keeping special poison ivy wipes and soaps on hand if you plan to spend time outdoors. If used immediately after contact, these products can help reduce the body’s allergic reaction to the oil.
  • More severe cases – especially those resulting from breathing in the smoke from burning poison ivy — may require a visit to the doctor or even the emergency room. These patients can be treated with prescription antihistamines and/or steroids.
Credit: Robert Benner Sr via Flickr

Credit: Robert Benner Sr via Flickr

If all of this weren’t bad enough, researchers are finding that poison ivy is not only becoming more widespread, its sap is becoming more powerful in the past few decades. That’s because, like many plants, poison ivy thrives when carbon dioxide levels rise.  In fact, scientists grew poison ivy under high carbon dioxide levels and found it produced more of the itch-inducing oil urushiol and grew twice as much – raising the possibility that this prolific plant could smother young trees that will become tomorrow’s forests. Read more about a study examining the effects of carbon dioxide on poison ivy.

Starting to itch yet? Here are the 3 facts from Harvard Health:

·         The rash is NOT contagious.  It looks unpleasant, but it won’t spread on you or to another person.

·         If you have the rash once, you can get it again.  One exposure doesn’t make you immune to it. In fact, if you get it once you’ll likely get it again if you come in contact with the oil.

·         You don’t have to touch a poison ivy plant to be affected by it.  Breathing in smoke given off by burning poison ivy can cause an allergic reaction in the lungs that may require immediate medical attention.

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