Poison Ivy: Beware the Oils
As the temperature rises, so do your opportunities to commune with nature. Don't let poison ivy ruin your plans!
One beautiful summer day, Joanna recruited her two young children to help her work in the backyard. After working in the vegetable garden, she and her kids turned their attention to the patch of weeds growing at the back of the yard and along one side of the house.
The next morning, Johanna awoke to find a slightly uncomfortable rash erupting on her arms and lower legs. So did her daughters. Over the course of the day, their rashes grew progressively worse. By Monday morning the three were scratching furiously. By mid-afternoon, they were in the doctor's office. The diagnosis? Poison ivy.
Poison ivy, as well as poison oak and poison sumac, grows almost anywhere—deep in the woods, at the local park, or in your yard. Every year, 10 to 50 million U.S. residents are affected by poison ivy, oak and sumac.
The culprit behind the extremely uncomfortable allergic skin rash of poison ivy, oak and sumac is urushiol (pronounced "you-ROO-shee-ol"), an oily substance found in every part of the plant except the pollen. Upon contact with the skin, urushiol is almost immediately absorbed. If not removed quickly—within about 10 minutes—an allergic reaction (in most people) begins with redness and swelling followed by extreme itchiness, and then by blisters (filled with a yellowish fluid) that can break open, causing crusting and scaling.
The full-blown rash usually develops within 12 to 48 hours, but people who have never been exposed to poison ivy may not see a full blown rash for seven to 10 days. Although the itching and swelling can be treated and controlled, there is no cure per se for the rash itself, which usually takes 14 to 20 days to run its course.
"Catching" the Rash
Approximately 80% to 85% of the US population is allergic to urushiol. However, most people don't develop a rash upon first exposure, but rather after repeated exposures. In addition, sensitivity to urushiol often decreases with age, so children tend to be much more susceptible to urushiol-caused rashes than adults.
Despite what you may have heard, you can't "catch" the rash from someone who has it, nor can you "spread" the rash from one part of your body to another by scratching. You must have direct contact with urushiol yourself.
However, you can come into contact with urushiol in a number of ways:
- Touching the sap —contact with the sap of a poison ivy, oak or sumac plant exposes you to urushiol. And, since urushiol remains active for months, this includes coming into contact with dead plants.
- Carriers of the poison —anything that comes into contact with the oily urushiol will be a conduit, including skin, clothing, backpacks, tools, and carpeting. It's even possible to become infected by handling firewood that has lingering traces of poison ivy, oak, or sumac.
- Furry friends —pets are an especially good conduit for urushiol. While their fur protects them from getting the rash, the urushiol readily sticks to their fur, then spreads to anything that touches it—including you!
- Air transport —when poison ivy, oak or sumac is burned, airborne urushiol particles can come in contact with the skin and cause a rash. If inhaled, these particles can cause a rash in the lungs, a very serious condition. Accordingly, you should never try to remove or dispose of these poisonous plants by burning them.
Treatment at Home
It takes about 10 minutes for urushiol to be fully absorbed into the skin. So if you know you've come in contact with it, the best treatment is to wash the contaminated skin in cold water as soon as possible. Once the rash has developed, there are a number of treatments that will lessen its severity, including:
- Cold or lukewarm showers
- Baths mixed with oatmeal compounds
- Anti-itch creams and lotions
- Topical corticosteroids
If you cover the rash or blisters after applying cream or lotion, do so with a gauze pad, and cover them very loosely since contact with the air helps heal the rash. Avoid scratching the rash and don't break open the blisters caused by the rash. Though the liquid within the blisters will not spread the rash, bacteria on the fingers and under the fingernails can cause the rash and/or blisters to become infected.
When to See a Doctor
Although poison ivy, oak and sumac usually can be treated without medical attention, see a doctor if:
- The rash becomes severe.
- The itch cannot be controlled.
- The rash effects the eyes or mouth, especially if either area begins to swell shut or if previous bouts with poison ivy, oak or sumac have been extremely severe.
In such cases, your physician or dermatologist will generally prescribe prescription-strength cortisone creams, or in extremely severe cases, oral steroids, to control itching and swelling. In addition, since airborne urushiol particles pose an extreme health danger, seek immediate medical attention if you think you or your child has inhaled such particles, even if symptoms have not yet occurred.
The best way to avoid getting a poison ivy, oak or sumac rash is to avoid contact with urushiol.
- Cover up —when walking or working in areas where these poisonous plants may lurk, wear long-sleeved shirts and pants and tuck your pant bottoms into your socks. Next, become familiar with what these plants look like, and avoid them. Since they can grow in somewhat different configurations, the old adage of "Leaves of three, beware of me" tends to be of only limited help.
- Clean up —if any of your clothing, tools, furniture or carpeting comes in contact with urushiol, wash them thoroughly, being careful not to transfer the urushiol to your skin. Do the same with a pet that has been exposed to urushiol.
- Pull it up —it's best to hire a professional to remove poisonous plants from around your house or garden. However, if you decide to do it yourself, be sure to pull the entire plant (including the roots) and wear clothing protecting as much of your skin as possible. Never burn the plants.
American Academy of Dermatology
American Academy of Family Physicians
Canadian Dermatology Association
Canadian Family Physician
Outsmarting poison ivy and its cousins. US Food and Drug Administration website. Available at: http://www.fda.gov/fdac/features/796_ivy.html .
Poison plants: ivy-sumac-oak. American Academy of Dermatology website. Available at: http://www.aad.org/pamphlets/PoisonIvy.html .
Last reviewed November 2009 by ]]>Brian Randall, MD]]>
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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