Identifying, Avoiding and Treating Poison Oak

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Leaves of three, let them be

Picture it: the birds are chirping; the bees are buzzing. The world outside your office window is turning green and sunny, luring you away after a long, bleak winter spent indoors. You head home to lace on your hiking boots or perhaps hop on your bicycle, and strike out into nature to celebrate the return of your old friend, spring. Maybe you ventured off the path or maybe your dog romped through the undergrowth, but a few days later you notice a slight rash and annoying itch. As soon as the red welts appear, you know the truth. You’ve been victim to one of Mother Nature’s oldest pranks: poison oak.

Poison oak, formally known as toxicodendron diversilobum, grows plentifully across the Western states of America. It mostly grows below 5,000 feet elevation in wooded areas, both shady and full of sunlight.

“Poison oak is abundant in Oregon,” says Molly Allen, environmental educational specialist at the Bureau of Land Management. “It’s native to this area and while we do try to keep it from encroaching on trails, it’s part of our natural plant life and we just have to be aware of it whenever we go outdoors.”

Although it grows year-round, poison oak is most potent in the spring, when it produces small white flowers and waxy leaves. It’s then that the plant produces the highest levels of urushiol, a toxic substance that often causes contact dermatitis.

“A great majority of people are allergic to the oil from poison oak,” explains Dr. Mary Murdoch of Southern Oregon Pediatrics in Medford. “You can often see the exact place where the plant touched, or linear rashes where it dragged across the skin.”

Poison oak rashes are most often red, bumpy and extremely itchy. They may also produce clear blisters that can become infected when the sufferer scratches and breaks the skin.

Poison oak is so concentrated that a sample the size of a grain of salt is enough to cause a reaction in most people. And the oil can stay around for days or even weeks, on shoes, clothes or even pet fur.

“If you know you have been exposed to poison oak, you need to think about everything you have come into contact with,” Murdoch notes. “Take a shower with a strong soap. Wash all your clothes and even car seats and furniture. Otherwise you risk re-exposing yourself every time you touch the contaminated surface.”

If you have the unfortunate luck to come into contact with poison oak and have a reaction, you can most likely treat it at home. “As soon as you are able, run hot water over the affected area,” advises Murdoch. This breaks down the urushiol and causes the body to generate its own histamine response. “After you moisturize well, you can apply an over-the-counter steroid cream like hydrocortisone,” she adds.

If the rash persists or is extremely uncomfortable, Murdoch recommends an office visit for a stronger prescription. “If you are miserable or suspect that you are developing an infection, we can prescribe an oral steroid such as prednisone,” she says.

Of course, preventing a poison oak reaction in the first place is the best course. Anyone who plans to spend time outdoors near trees or foliage should learn to identify poison oak first.

“The old saying ‘leaves of three, leave it be’ definitely applies to poison oak,” Allen says “If you see a plant with three leaves growing together, be aware. Poison oak can be green or red in fall, and grows on the ground like a shrub, up trees like vines, and even in thick sticks.”

As another saying goes, “an ounce of prevention is worth a pound of cure,” and when it comes to poison oak, the best prevention is to stay far away from any suspicious leaves.

“This time of year we see a spike in cases,” says Murdoch. “It’s definitely something you would prefer to avoid.”

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Critical 10 minutes: Reduce reaction by fast treatment

  • Wash affected area with warm water and soap. (Dish soap, like Dawn, can break down the oil).
  • Carefully remove any clothing that could be contaminated. You may need to wear gloves to avoid transferring oils by touch.
  • Apply moisturizer and a calming, topical agent such as calamine lotion or hydrocortisone.
  • Apply a cool compress for itchiness.
  • Consider taking an oral antihistamine.
  • Do not scratch or break any blisters that form.
  • Take warm baths with oatmeal or a cup of baking soda.
  • If your rash is not improving after a week, or if you think your rash may be infected, visit your health provider.

What to do in the woods

If you’re not near home, wash the affected place as soon as you can. If you have drinking water with you, use that or a stream or creek if nearby. Don’t scrub. Consider carrying outdoor skin cleansers, such as Tecnu or Zanfel, in your backpack.

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