How To Treat and Prevent Trail Running Blisters

How to manage this ongoing challenge for trail and ultrarunners

Photo: Getty Images

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Ah, the joys of trail running! The wind in your hair, the freedom in your stride, the beautiful views, and uggh, a blister on your foot. Those pesky little blisters that haunt us like clingy exes. We’ve all been there, my fellow runners, fighting the ultimate foot nemesis. But fear not, for we bear some tips and tools to guide you through this blister-filled journey.

What Causes Blisters While Trail Running?

In other words, why do we get blisters? Although they are one of the most common dermatologic and foot problems among ultra-endurance runners, factors such as where, how and why they occur are sometimes misunderstood. 

It turns out, friction between the skin of the foot and the running sock (assuming that you do run with socks) is the main culprit. Blisters are more likely to develop when there is greater pressure exerted on your skin due to friction. Various factors, such as calluses, bunions, improperly trimmed toenails, ill-fitting shoes, new shoes that haven’t been worn yet and trail terrain that causes a change in your repetitive gait pattern can all contribute to increased pressure on specific areas of your skin, which can inevitably lead to the formation of blisters. 

Additionally, foreign objects that find their way into your shoe, known as “particulate matter” (sand, mud, dust, or grass stubble), can also cause problems. When some of this material gets trapped between the skin and the sock or between the sock and shoe, it enhances friction and becomes a breeding ground for blisters.

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How To Prevent Blisters When Trail Running?

As much as we’d like to say these annoyances are entirely preventable, this isn’t so. Sarah Zimmer, PT, DPT of Boulder Sports Physiotherapy says blisters are sometimes inevitable depending on the time on your feet, if your socks and/or shoes get wet on the trails, and other various elements that increase friction within our socks and shoes. 

Zimmer’s best tips to prevent blisters include:

  • Take care of your calluses, the thickened sections of skin that typically form in high-friction areas “Many trail runners develop calluses between or underneath their toes, the ball of the foot, or on the back/sides of the heel,” Zimmer says. “The spots with calluses will likely be the spots you get a blister. Calluses can become painful, which may lead to changes in your running form or gait as a result.” 
  • Make sure your shoes are the right size (which sometimes means going up a half or full size). Shoes that are too tight can cause extra friction especially as your feet swell up during runs. However, shoes that are too big can also create excessive movement and friction, which can also translate to blister formation. (Keep in mind, too, that feet can swell a full size or more in hot, humid conditions during multi-hour trail runs.)
  • Wear moisture-wicking socks made with materials that wick moisture away from the skin to keep the skin as dry as possible, such as Merino wool,Coolmax or bamboo. One of Zimmer’s favorite brands of socks is Drymax, although Balega, Injinji, Swiftwick, Bambuwerx and Darn Tough are a few other brands that come out on top when surveying trail runners. Cotton socks can actually contribute to blister formation, as they hold in heat and moisture while increasing friction, creating a perfect storm for blisters.
  • Use KT Tape or a similar tape to cover your toes, heel, and the ball of your foot. The heel in particular is a spot that can be painful when blisters arise. Make sure to wrap tape firmly around the area and re-applying tape regularly (every couple of days) to ensure the wrap stays put.
  • Soak your feet in an Epsom salt bath after your run if you want to heal blisters quickly. Many experts suggest doing so for 10 minutes once or twice per day. Epsom salt contains magnesium, which reduces swelling and pain associated with blisters.

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How To Fix Blisters When Trail Running

Let’s face it: When we’re seeking out experiences that involve running long miles over numerous days and trudging through river crossings, we can’t keep ourselves entirely safe from an occasional blister or the hot spots caused by friction that can irritate skin before blisters arise.

Amelia Boone, an accomplished ultrarunner and obstacle course racer, is nicknamed the Queen of Pain, but really, she could be the Queen of Feet based on her experience managing blisters. She says she brings her own basic blister kit to ultramarathons in case blisters arise.

“The kit I have on me is super tiny—it’s a needle and a vial of tincture of benzoin wrapped in Rocktape/kinesio tape and an alcohol wipe,” she says. “The needle can be used to pop a blister on the fly, the tincture of benzoin makes skin super grippy for tape application, and then the tape covers up hot spots and blisters.”

In her mid-race drop bags, Boone generally leaves extras of those to replace/refresh if needed. She also recommends Leukotape as another great option for those who are really prone to bad foot issues as it is much more durable than Rocktape. While some people swear by duct tape, Boone says she uses  that as a last resort

She also carries a small container of lube (Squirrel’s Nut Butter) but recommends trail runners experiment with lube and other skin treatment products to find out what works best for their feet.

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“I find some lubes way too heavy and cause more issues, and I’m not a big fan of powders, but I know others are,” she says. “So if you use any of that stuff for your long runs and that works, then keep small tubes of those in your drop bag or on your person.”

In the world of running, blisters have become an all-too-familiar foe. These pesky companions can turn a blissful jog or a multi-hour adventure run into a painful ordeal. Although many things can cause blisters, friction between the skin and running sock is typically the primary culprit. Though blisters may be inevitable in some cases, there are measures you can take to minimize their occurrence. Taking care of your calluses, ensuring proper shoe fit, using moisture-wicking socks, and employing tape or wraps can add protection. While blisters may still sneak their way into your running journey, armed with these tools and tips, you’ll be better prepared to minimize this common foot nemesis and keep running with joy.



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