Hiking is the perfect way to celebrate fall—until you return home with a red itchy rash all over your ankles, arms, and butt.
See, in the fall, poison ivy doesn’t look like the glossy green plant your middle school science teacher warned you about. Instead, as the temperatures drop, the leaves crisp up and turn yellow, red, or orange. So can poison oak and sumac leaves, which also come covered in the urushiol (say it with us, you-ROO-shee-all) antigen.
Here’s where it gets really fun: In response to coming into contact with urushiol, the body’s immune system launches a full-blown attack on the invader. The result: About 12 to 48 hours later, a red, blistery rash pops up wherever the plant brushed against you, says Robert T. Brodell, M.D., professor and chair of dermatology, at the University of Mississippi Medical Center.
It typically takes about a week for the rash—and insanity-provoking itch—to clear up, he says. But in some cases it can take even longer, and it may even require emergency medical attention, especially if you accidentally wipe the urushiol from your arms to your mouth or eyes.
Here’s how to avoid the whole thing:
Know It When You See It
In the northern and western United States and around the Great Lakes, poison ivy grows as a shrub. In the east, Midwest, and southern states, it grows as a vine. No matter where you’re hiking, though, its leaves are divided into three small, pointy leaflets. Some poison ivy plants grow green berries that turn off-white in early fall, according to the American Academy of Dermatology.
Poison oak, however, honestly just looks a lot like an oak leaf. Handy, right? If you don’t know what an oak leaf looks like, each one is composed of three rounded leaflets. While the plant most often grows as a shrub, it can grow as a vine out west. It sometimes has yellow-white berries.
Poison sumac is typically larger, growing out of pools of standing water as a tall shrub or small tree. Each leaf contains seven to 13 leaflets. Sometimes, you’ll see black splotches on the leaves. These spots are urushiol, which when exposed to air turns brownish-black, says Brodell.
Wearing gloves, a long-sleeved shirt, and pants that cover your ankles can go a long way toward keeping urushiol away from your skin, says Brodell. But let’s be honest: What you wear is really going to depend on the weather. Plus, if you’re a face-toucher, urushiol on your hands—whether they are covered in gloves or not—can easily wind up on your face.
Slather on a Shield
If you’re not digging the “cover up” strategy, using an ivy blocker, a bentoquatam-containing cream that goes on your skin to act as a barrier between your skin and the plant, can make a huge difference in whether or not you wind up with a rash, says Brodell. You can buy them online or OTC at your local drugstore.
Keep On the Trail
Fight the temptation to venture off of the path and go exploring—or to hide behind a tree or bush when nature calls. “You’d be shocked how many people get poison ivy on their genitals,” says Brodell. As long as you stay on the dirt path, you know you aren’t traipsing through or butting up against poison ivy.
No matter what you wear, you should take a warm, soapy shower the minute you get back home to remove any urushiol before it absorbs into your skin, says Brodell. This step is especially important if you come home from the trail with black spots on your skin. Just like on poison sumac, urushiol turns black on your skin when it comes in contact with the air. So if it’s on your skin, you’re going to see it within 15 minutes or so. “The shower might not keep you from getting poison ivy, but you won’t get nearly as much as you would otherwise,” he says.
Keep Your Gear Clean
“The gloves you wore hiking last fall can still have poison ivy on them,” he says. “So can your dog who went on the trail with you.” That’s why, post-hike, it’s important to wash off everything—and every furry friend—that was with you. Otherwise, you could wind up with a mysterious rash days, weeks, or months later.
Already Have It? Here’s What to Do
Since most cases of poison ivy will eventually clear up on their own, your biggest concern should be easing the itch. For that, Brodell recommends applying some one percent hydrocortisone cream, a low-dose topical steroid, to the rash as much as you need to keep from going crazy (this should be at least once a day).
While scratching won’t spread the poison ivy (that’s just a myth), it can cause extra irritation and allow for infections to take hold. If, after applying hydrocortisone, you still feel scratchy, try applying an ice pack. Applying heat may feel good at first, but it will actually make the itching worse in the long run, says Brodell.
If the rash is on your face, genitals, or a large portion of your body (read: more than a few square inches of skin), don’t try to treat it on your own. Brodell recommends going to your dermatologist, primary care physician, or an urgent care clinic. There, a doctor will likely prescribe you the oral steroid Prednisone to relieve your symptoms and help you achieve sweet, sweet relief. Docs also have access to stronger topical steroids than the hydrocortisone that you get over the counter.