June 4, 2012
Poison ivy contains the chemical urushiol, which causes an itchy rash in 90 percent of people.
Photo by Sue Weaver
Avoid romping through poison ivy if you don’t want an itchy rash!

Have you ever had poison ivy? The itchy rash and blisters, not the plant. I haven’t had it—but I’m a goat! Most animals can’t get poison ivy, and to goats, poison ivy is just a tasty weed. However, according to the Poison Ivy, Oak and Sumac Factsheet published by the Texas Department of Insurance, approximately 90 percent of Americans are allergic to urushiol (pronounced oo-roo-shee-ohl), a chemical in the sap of poison ivy, poison oak and poison sumac plants. Ow!

Urushiol is so potent that 500 people could itch from the amount of urushiol covering the head of a pin. One-quarter ounce of urushiol could cause a rash in every person on earth. Only one nanogram (that’s a billionth of a gram) is needed to cause a rash in one person, and the average person is exposed to 100 nanograms each time they come in contact with it. Urushiol stays active for one to five years, even on dead plants and garments, like jackets and hiking boots. Specimens several centuries old have caused rashes in sensitive people. Urushiol is very potent stuff!

Poison ivy grows throughout the United States, southern Canada and northern Mexico, except at high altitudes and in arid desert climates. Identifying poison ivy can be tough. Sometimes it grows like a low shrub and sometimes it vines. It even grows up fence posts, walls and trees. Poison ivy has three somewhat shiny leaves on the same stem and they’re green during the summer months but turn red in the fall, often blending with the plants around it. Some people seem to be immune to poison ivy, but if that’s you, don’t be complacent. Sometimes immunity fades. It’s always best to avoid this plant.

So what do you do if you look down and you’re tramping through a patch of poison ivy? Urushiol can penetrate your skin in minutes, so wash yourself down as fast as you can. Water from a stream or water bottle can help, but get home as fast as possible and clean the area with lots of rubbing alcohol. Then take a shower with soap and warm water.

If you don’t get urushiol off in time, you’ll break out in a rash in four hours to up to four days. Poison ivy rash and blisters disappear in two to three weeks without any treatment, but it will itch intensely in the meantime. Try not to scratch! Scratching blisters open can cause infections, so soothe the itch and dry up them up using calamine or kaolin lotion, zinc oxide, baking soda paste or over-the-counter hydrocortisone products.

And be careful if your dog or goats stroll through a poison ivy patch. We can carry urushiol on our coats. If you think that’s happened, give us a warm, soapy bath and be sure not to pet us ’til you do.

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