Trail Runners Guide To Poison Oak

Clark Kent has his kryptonite, I have poison oak.

If I even look at poison oak, I get itchy.

I also live in Northern California, where it is EVERYWHERE.

And I love trail running, where you often can’t avoid contact with poison oak.

It all adds up to me slowly mastering the art of minimizing contact with the plant and dealing with its after-effects.

Poison Oak: The Scourge of Hikers and Trail Runners Everywhere

Not everyone reacts to the urushiol oils of poison oak (urushiol is the stuff that makes you itchy). Up to 70% of the population doesn’t react to the oil.

If you don’t: consider yourself lucky.

If you do (like me): my sympathies.

Not sure? Act like you react. Best to take precautions and assume you’ll react.

And here’s something to keep you up at night: according to Tecnu’s website (the makers of the best poison oak prevention and remedies out there – we’ll come back to them in a second), with repeated exposure, you can develop a reaction to poison oak at any time.


Know Thy Enemy: Identification

Poison oak leaves look a lot like oak leaves and usually grow in clusters of three – ‘leaves of three let it be’ as the old saying goes. But some varieties have five, seven or nine leaves per cluster.

Often (but not always, mother nature wouldn’t make it that easy), the leaves are shiny.

A photo of poison oak from the Tecnu website

The Rash Plant app can be a great resource on identifying poison oak and other itch-inducing greenery.

The leaves turn bright red in the fall.

Poison oak has the most oil (and is therefore the most dangerous to us trail runners) in the spring, but you can still get a rash from the red leaves in the fall and even the bare plant stems in the winter.

Unfortunately, I can confirm it’s possible to get a bare-stem rash first hand.

Usually the plants are low shrubs close to the ground, but if left to grow for long periods of time they can get fairly large. In one particularly nasty incident for me, I ran through a bunch of greenery weighed down by the rain. Only later did I find out that some of those plants (coming at me from above) were poison oak that had overgrown into the trees.

It’s not often I have to deal with poison oak rashes on my arms and shoulders, but it is possible.


Avoiding contact with poison oak is the obvious, (but not always terribly helpful) answer on how to prevent a rash.

If possible, avoid running trails that have poison oak (which isn’t realistic in my neck of the woods- the plants are everywhere), or avoid running trails altogether, which is (for me at least) an equally unrealistic option.

If you will be running a trail that has (or might have) poison oak, wear long pants and long sleeves to cover bare skin. There is light, summer appropriate, long sleeve gear that can minimize exposure in the summer.

Another alternative (and the one I usually use in the summer) is to wear light arm warmers and calf compression socks or sleeves. Calf sleeves cover the most-likely exposed part of my body, but are a little more summer appropriate.

My poison oak one-two punch: 1. Minimize exposure with calf sleeves and 2. remove whats left with Tecnu

The oils can stay on your clothes for a long time, so wash any exposed (or potentially exposed) clothes ASAP.

Pro Tip: Be careful removing clothes after a run – assume the outer side of everything is covered in urushiol oil.


Removing the Poison Oak Oil

If you’ve been exposed (or think you’ve been exposed), you need to remove the oil as quickly as possible from your skin to reduce the chances you’ll start to itch.

Don’t let the fact you’ve been out on the run for a long time without getting a rash fool you, rashes can take hours or weeks to develop. I’ve had rashes appear up to two weeks after exposure.

My go-to product for removing poison oak oil is Tecnu.

Tecnu is a cleanser specifically designed to battle poison oak, poison ivy and poison sumac. It’s a liquid you apply directly to your skin, rub vigorously for two minutes and then rinse off. I keep a bottle of it in my car with baby wipes – always accessible for a post-run wipe down.

For maximum impact, Tecnu should be applied within 8 hours of exposure.

I also often use Tecnu Extreme, which is a scrub that’s used in the shower more like a body wash.

Pro Tip: Remove your socks before wiping down your legs with Tecnu. More than once, I’ve been left with a small rash around my ankle when I’ve rinsed off while wearing socks and missed spots just at the top of my sock line.

Surviving Once the Itching Starts

Note: I’m not a doctor, nor do I claim any medical knowledge other than dealing with my own (regular) exposure. If you are concerned about your rash, or if it’s affecting your throat, eyes, or breathing, contact a qualified medical professional.

A selection of my poison oak prevention and treatment collection

Poison oak creates a blistering rash with lots of itching and oozing.

I’ll spare you all the photos here, but the Tecnu website has photos of the aftermath of exposure if you are interested.

Once the itching starts, there is little you can do other than minimize the itching and oozing and wait it out.

Products like Calamine lotion and Tecnu’s Calagel help dry the oozing and minimizing the itching.

If your rash is particularly oozy, cover it with a sterile loose bandage. However, keeping the rash (and the ooze) exposed to the air will help dry it out and help speed healing.

Usually the rash will take about a week to clear up.

Personally, I’ve found old school pink calamine lotion works the best. Plus, the smell of it always reminds me of summer camp.

Secondary Exposure

Once you’ve starting itching and oozing, the ooze (while super-gross) doesn’t spread your rash, although it may seem that way if the rash (from your initial exposure) continues to develop.

However, it is possible to get a rash from secondary exposure if the oils got on tools, clothing, dog fur or running shoes that you later touch.

Wash down anything that was exposed to the urushiol oil with Tecnu to prevent secondary exposure.


Good luck staying itch and ooze free on those poison oak-infested trails


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