Poison ivy: an oily menace that's getting nastier

Newsday.com
Kathy Wollard
September 8, 2008

Why does poison ivy make us itch, and is it true that it's getting more poisonous? asks a reader.

Itching all over after a hike in the woods or an afternoon of weeding? It's probably those "leaves of three" (let them be), aka poison ivy. At least 80 percent of us break out in an itchy rash when poison ivy oil touches our skin. And it's not just those shiny leaves we need to worry about. The whole poison ivy plant is a menace, from the bottom of its roots to the tip of its stems.

The culprit is urushiol, a yellow oil that sneakily smears on your skin when you brush against any part of the plant. Because a microscopic amount of urushiol (one nanogram, or a billionth of a gram) can cause a reaction, you'll never notice it's there. Until, that is, hours later ... when a red, itchy, blistering rash sprouts on arms, legs or face. Just as some react to ragweed pollen by sneezing and sniffling, so do most of us react to urushiol as an attacking foreign body.

So if you think you've come into contact with poison ivy, rush to the nearest sink and wash your skin well with cool or lukewarm soapy water (or a scrub product such as Tecnu). The idea: Remove the poison ivy oil before it bonds to skin proteins. Touching a poison ivy blister can't spread the rash, but urushiol left behind on clothes and shoes can cause a brand new outbreak.

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