As the weather warms up, and nature turns green again, now’s the time of year that we’re all dancing merrily through the woods, singing songs, and wearing our woven crowns of flowers and ivy. Or maybe that’s just elves. Anyway, we’re getting outside and pulling some weeds at least. And while it’s always fun to get into nature and enjoy the outdoors, we have to remember that there’s often danger lurking in plain sight. That’s right, I’m talking about that devilish bane of summer camps everywhere. I’m talking about Poison Ivy.

When we think about Poison Ivy, we should really expand our awareness to include its close cousins, Poison Oak and Poison Sumac. They’re all native to the Southeastern United States, and they can all cause one heck of an itchy rash. We all know these plants are toxic, but why? What is it about them that causes such a profound reaction in humans? The answer is urushiol. Urushiol is an oil that is produced by every part of the plant, including the roots, stems, leaves, and even berries. When our skin makes contact with this oil, it takes less than an hour for it to be absorbed into our cells. Once it gets inside, our skin cells start to display it on their surface and sort of wave it around for our immune system to see. A special type of immune cell, called a T-cell, sees it and goes, “OMG, that is NOT part of our body! Attack!” The T-cells proceed to attack the skin cells that hold the urushiol, and this inflammatory attack is what causes the rash.

What kind of rash?

The rash caused by poison ivy is usually red, bumpy, and intensely itchy. We’ll often see little clear fluid-filled blisters called vesicles, as well. A lot of times the rash will show up in lines, which shows where we have brushed past the poison leaves while walking. Sometimes, if the exposed skin area is large enough, there can be large patches of bumpy rash with vesicles. The rash should be well demarcated, meaning it should have clear, sharp borders instead of fading out slowly around the edges. If the rash has been scratched at, and it starts to feel tender and look hazy around the borders, this could mean a skin infection called cellulitis has developed from the bacteria under those dirty fingernails. 

So what do we do about it?

The first thing to do is wash it off! If you know you’ve had a poison ivy/oak/sumac exposure, try to wash the exposed skin with soap and warm water as quickly as possible. If you catch it soon enough, you may be able to wash the urushiol off before it has a chance to be absorbed into the skin. If you’ve already got the rash, the first thing to do is not scratch. Remember cellulitis? Don’t go there. The itch can be intense, so calamine lotion, cortisone cream, and an antihistamine like claritin or zyrtec can often help. Sometimes, if the rash is more widespread or isn’t responding to OTC treatments, your doctor may prescribe a stronger steroid cream, like triamcinolone. If the rash is very widespread, or involves the face or eyes, you may even need systemic steroids in the form of a shot or pills. Just remember, once that urushiol is absorbed into your skin, it sticks around for 1 ½ to 2 weeks, no matter what you do. So it’s important to continue treatment for that long or else risk a rebound rash if you stop medication too early. Also, remember that urushiol is an oil, just like olive oil, motor oil, or any other oil, and it will stick to just about anything! Make sure you wash any clothes, watches, shoes, belts, hats, backpacks, etc that may have been exposed to the plant. Use soap and water (do the best you can without ruining your stuff). You can be re-exposed by touching those objects. Same goes for pets! Dogs can carry urushiol around on their fur for days.

What’s this stuff look like?

You’ve probably heard the saying, “Leaves of three, let it be.” It’s a good reminder for Poison Ivy and Oak. Each of those looks like a small, thin vine with clusters of three broad leaves sticking off of it. We also sometimes see thick vines with hairy-looking projections running up trees or power poles. Poison Sumac, on the other hand, appears bushier, with clusters of whitish or light green berries that tend to sag downward.

Does Poison Ivy spread?

Yes and no. Once the rash has started, scratching it does not spread it to other parts of your body, and it is not contagious to other people. The fluid in the rash vesicles is harmless and does not contain urushiol. Poison Ivy does not spread through the bloodstream, and there is no such thing as blood-borne Poison Ivy. What can happen is what was mentioned above- repeated exposures to urushiol on clothes, hats, pets, etc. And if you get the oil on your hands, you can spread it around to any part of your body.

Are there people who aren’t allergic?

There may be a very small subset of the population that does not react to Poison Ivy. Small. Most people who think they aren’t allergic will get a rude awakening if they go and rub this stuff on their skin. Don’t try it.

The moral of this story is, have fun in the woods, but keep your eyes open. Stay away from poison plants, and if you do come in contact, wash it off as quickly as possible. If that big mean rash starts up anyway, come see us at ADPC. We’ll get you taken care of.

-Kyle Adams, MD

Dr. Adams practices Family Medicine at Auburn Direct Primary Care. He is actively accepting new patients, and we would love to have you join the ADPC family. If you’re ready to get started, click Here to enroll with us now!