Poison Oak + Poison Ivy: What You Need to Know

One of the worst ways to ruin fun in the outdoors is having a run in with poison ivy, poison oak, and poison sumac. These infamously itchy plants are a nationwide nuisance. They’re like a dastardly invention of science fiction: voracious vines that poison humans on contact. But they’re not made up, as many of us are already painfully aware. Fortunately, science explains why poison ivy irritates our skin and offers some ways to combat it.

Watch how elite ultra-runner Janessa Taylor beats the itch of poison oak and poison ivy, so she can keep doing what she loves: crushing miles out on the trail. 

The “Poison”

The itchy, red, and often blistery rash is not from a true poison, but from an allergenic oil called urushiol, which poison ivy and its relatives uniquely produce. It permeates into the skin, where it triggers an irritating immune response. The rash usually appears a day or two after contact, and lasts from a few days to a few weeks.

The telltale signs of contact with urushiol: red inflammation and raised bumps. Photo courtesy TecLabs Inc.

The oil easily transfers to anything that brushes the plant, and it can be transferred many times again. If you’re allergic, just a tiny bit can cause a reaction, so it will spread all over if you aren’t careful. You can get it by touching the plant directly or from fabrics, other objects, or pets that have come in contact.

Just how miserable the reaction gets depends on a lot of things. Each person differs in level of sensitivity, and the amount of exposure matters, too. Some people might barely touch it and break out all over, while others can trip face first into a big patch but only become mildly itchy, and a minority of people aren’t allergic at all. In part, the molecular arrangement of urushiol explains this variability: Technically a fat, the more unsaturated urushiol is, the more virulent is the allergic reaction, and in studies of such cases up to 90% of participants reacted after contact. Still, your sensitivity can even change over time. You might be highly susceptible as a kid but not as an adult, or vice versa.

• The bad news: Most people are allergic to urushiol, about 80% of the people in the U.S.
• The really bad news: Even if you’ve never had a reaction, it’s possible to develop the allergy after repeated contact.
• The good news: Urushiol takes some time to absorb into the skin, and you can cleanse it shortly after contact to minimize or even eliminate your reaction.
• The really good news: There’s a line of products made by Tec Labs known as Tecnu that’s super effective at removing the oil, even without water.

Poison ivy's notorious leaves of three are nice to look at, but contain an irritant known as urushiol in leaves, stems, and vines. Michael Battey.

The Plants

Of course, the best way to prevent a rash is to simply avoid the poison plants. Even though that’s not always possible if you spend a lot of time outside, knowing a bit about them can help you prevent contact in many situations.

Each of the poison plant cousins occupies a slightly different habitat, but collectively they are found in every contiguous U.S. state and nearly every Canadian province, from sea level to about 5,000 feet elevation. Poison ivy is most common in the Eastern and Central U.S. while poison oak is mostly in the West, but their ranges overlap in places. They most often grow in forest areas with a mix of sun and shade. In arid environments, they are usually confined to damp, shady spots. Poison sumac is a shrub or small tree that grows only in disjunct pockets of the Eastern U.S. and favors swampy soils.

Poison ivy and poison oak look similar; they are small shrubs or vines with leaves in groups of three. The exact appearance varies quite a bit with geography and season, however, and they can be confused with a few other three-leaved plants that are nontoxic. If you aren’t savvy on plant identification, it’s best to follow the old saying: Leaves of three, leave it be.

More bad news is that all parts of the plant contain urushiol, however, and they lose their leaves in winter. Even defoliated or dead plants can cause a reaction, though it’s much rarer. No matter the time of year, avoiding the itch-inducing plants can be tricky. Luckily, there are several ways to minimize your contact when playing or working outdoors.

The three species of urushiol-bearing plants: poison ivy (top), poison oak (middle), and poison sumac. Photo courtesy TecLabs Inc.

Prevention Tips

• Stick to the trail.
• Wear sturdy shoes, long socks, and long pants. The plants can sometimes overhang the trail and be unavoidable.
• Wear gloves, long sleeves, and eye protection if working with brush.
• Camp in formerly used, clear sites away from dense understory.
• Avoid firewood with vines attached. They could be bare poison ivy or oak, which is still toxic when burned and can even affect your lungs.
• Try to avoid touching parts of your body that might have come in contact with urushiol to keep the oil from spreading before you have a chance to wash.
• As soon as possible, wash everything that might have come in contact, and keep contaminated clothes separate from others before they are washed.
• Even if you get a rash, wash all over with Tecnu to eliminate lingering oils before it gets worse.

Treatment

The key is to wash as quickly as possible and keep the oil from spreading. Even if you aren’t sure you touched poison ivy, poison oak, or poison sumac, it’s best to wash anyway. By the time you start itching a day or two later, you’ve probably unknowingly spread it to other parts of your body that will soon break out as well. There are a few ways to remove the oil. Soapy water is one of them, but it’s not always practical.

A better alternative to soapy water, Tec Labs has created a line of wash products specifically designed to neutralize urushiols. Its Tecnu Original Outdoor Skin Cleanser is a gentle wash that breaks the bonds of proteins formed when urushiol comes into contact with bare skin. Simply rub Tecnu on the affected area, let it sit for 2 minutes, then rinse or wipe it off. Do this within 8 hours for the best chance of stopping the rash. Tecnu works even without water, and it’s the perfect quick fix, even in the backcountry. At home, it also works on fabrics (soak your clothes in a bucket with Tecnu Original Outdoor Skin Cleanser added to water prior to laundering), objects, and even your dog. They also make a Rash Relief anti-itch spray to use if you get a reaction.

Watch how elite ultra-runner Janessa Taylor beats the itch of poison oak and poison ivy, so she can keep doing what she loves: crushing miles out on the trail. 

For complete instructions on using Tecnu, plus tons more information about the science of poison ivy and treatment, visit Tec Labs.