4 Ways to Prevent Runner’s Toe (and What to Do If It Happens Anyway)

There’s a popular sign that you’ll often see spectators holding along the sidelines of marathons: “All Toenails Go to Heaven.” It’s a joke made at the expense of those racers who are no longer sporting a full set of 10, thanks to an all-too-common condition known as “runner’s toe” in which a toenail turns black and blue and might fall off entirely. Yep, racking up mileage can have unintended consequences for your pedicure. 

Fortunately, while runner’s toe may look somewhat unsightly when you’re wearing sandals, it’s not super serious and rarely comes with complications—as long as you treat it correctly. Here’s what podiatrists want you to know about this condition before you start doing your own bathroom surgery on your next black toenail from running. 

What Is Runner’s Toe?

Runner’s toe is what happens when you put a toenail under lots of pressure or expose it to incessant friction, causing microtrauma that leads to bleeding under the nail plate and dark discoloration. (The medical term for it is subungual hematoma.) It usually crops up on whichever of your toes is the longest—typically the big toe or second toe—but it can occur on any of the five.

Sometimes, this happens if you simply drop something heavy on your foot or stub your toe extra hard. But the condition gets its famous name from those long-distance runners who repeatedly hit their toenails up against the front edge of their shoes until they bruise. The more you run, and the longer you go, the more likely you are to get runner’s toe. 

The condition is especially common if your running shoes are too big, short, or narrow; if you have a long second or third toe; or if you’re running on steep downhill terrain that has your feet slamming up against the toe box in the front of your shoes. This might sound painful, but many runners say you won’t actually feel the damage you’re causing in the moment—only afterwards.

“You’ll start getting bleeding underneath the toenails or blisters,” says Mark Mendeszoon, an Ohio-based podiatrist who specializes in sports medicine. That blood can make the nail appear black. 

One 2019 review found that runner’s toe was one of the most common dermatological injuries among ultramarathoners in particular, and an older review from 2006 found that up to 14 percent of marathoners end up with toenail injuries on race day.  

But it’s not just runners who suffer from runner’s toe. Walkers can get it from putting in long miles in less-than-ideal shoes, too, while rugby, basketball, and soccer players can get it from stubbing their toes. Cyclists are also vulnerable, Dr. Mendeszoon says: “Those cleats are cut very narrow and they’re very unforgiving,” he says. “Your feet start taking a beating when you start swelling or if you’re always pushing down the pedals with the toes curling down.”

Common Symptoms of Runner’s Toe

When you get runner’s toe, the bleeding underneath the nail turns it black and may cause uncomfortable pressure. From there, a few different scenarios can happen, according to Seattle-based podiatrist J. John Hoy, who has extensive experience in sports medicine:

If you lose the nail altogether, another will grow back in its place, so long as there’s no damage to the cells in charge of regrowing your nail. But if you keep getting runner’s toe over and over again, eventually the nail that grows back in will be thickened and discolored. “And that can add more pressure to the underlying tissue,” Dr. Mendeszoon says, which makes runner’s toe even more likely to return for a repeat visit. “Once people start getting runner’s nails and traumatized toenails, it’s there for the long-term unless you stop working out,” he says.

How to Treat Runner’s Toe

Unfortunately, there’s not a ton you can do to treat black toenails from running other than giving it time. 

If the nail gets loose, Dr. Mendeszoon says many people will resort to bathroom surgery to take it off—but you’ll want to be careful if you try that route. “Make sure you clean your instruments with alcohol and do everything as hygienically as you can,” he says, warning that you could give yourself an infection if you try to just rip off the nail with an unsterilized clipper. It could also lead to additional trauma and slow your healing process, which is why experts discourage this method.

Rather, it’s safer to just leave the damaged nail alone, keeping any loose bits trimmed so they don’t catch on clothes or sheets. A new nail should eventually grow in one way or another.

In the meantime, Dr. Mendeszoon says it’s perfectly safe to continue running as long as it’s not causing you major pain (although it could lead to chronic runner’s toe).

When to Talk to Your Doctor About Runner’s Toe

If runner’s toe is causing you a lot of pain, you may want to check with a podiatrist to get the damaged toenail removed, which could help you find some relief.

You’ll also want to schedule a visit with the podiatrist if you suffer from repeat black toenails and they’re getting in the way of your workouts. Dr. Mendeszoon says there might be a structural reason that you’re prone to runner’s toe; a bunion, arthritis in the toe joint, super-long toes, or muscle imbalances could be the culprit. A specialist may be able to help you find a solution that keeps runner’s toe from coming back.  

Another reason to see the foot doc: continuous bleeding under the nail, as there might be cause for concern about blood loss or lack of circulation, Dr. Hoy says. In this scenario, a podiatrist might need to drain the blood or take out the nail. 

How Long Does Runner’s Toe Take to Heal?

Once you’ve got runner’s toe, you can expect to be dealing with an ungainly nail for about six to nine months. However, the healing process doesn’t always look exactly the same. 

That’s because a few things can happen to black toenails, Dr. Hoy says. Sometimes, the body will simply reabsorb the blood under the nail plate that’s causing the bruise, and it will slowly fade away or change colors to yellow or brown as it disappears. Other times, the bruised section grows out with the nail. Or, the pooled blood might put enough pressure on the nail bed that the nail separates from your skin underneath and falls off entirely—sometimes weeks or months later. Either way, Dr. Hoy reiterates that it’ll take some time to regrow a fresh, uninjured nail.

How to Prevent Runner’s Toe

Even if you’ve got a long toe that loves to bump up against the front of your shoes when you’re running, walking, or cycling, there are a few things you can do to prevent runner’s toe. 

1. Prioritize Properly Fitting Shoes

Dr. Mendeszoon says the most crucial factor in preventing runner’s toe is getting shoes that fit properly. You should have at least a thumb’s width of space between your longest toe and the front of the shoe, and enough room side to side to comfortably splay out your toes and give them a wiggle. (Pro tip: Shop for shoes near the end of the day when your feet are swollen to better mimic the size they’ll be at the end of a long run or ride.)

2. Wear the Right Socks

Dr. Mendeszoon also suggests avoiding socks with ridges on the tips of the toes for runs and long walks. That extra fabric can put excess pressure right on the nails. And make sure your socks are not so thick that they make your shoes too tight.   

3. Practice Good Foot Hygiene

Trimming your toenails short is a smart move so you don’t have excess nail that bangs up against your shoe. Dr. Mendeszoon recommends trying to keep your feet dry, too, since a hot, sweaty environment in your shoes can increase the risk of toenail injuries. If you know your feet naturally sweat a lot, he suggests trying to diminish the moisture by powdering your shoes or spraying your feet with an anti-perspirant, “just like you would with your armpits,” he says.   

4. Consider Tape

Dr. Mendeszoon adds that some people wrap their problem toes in duct tape for extra protection. “Wrap two layers around your toe and toenail, then do a ‘U’ on top and mold it together, making sure there’s no wrinkles,” he says. “That can reduce a lot of the friction and pressure.” Just be sure not to wrap the tape so tight that it strangles the toe and cuts off circulation.

Other Causes of Black Toenails to Know

Although runner’s toe is fairly innocuous, Dr. Hoy warns that melanoma can also cause a similar kind of dark spot underneath a toenail. But there’s a fairly easy way to tell the difference: “If it’s a bruise, it will just continue to move up as the nail grows. Whereas if it’s a cancer, it’ll stay there and it might get bigger or start changing in symmetry or borders or color,” he says. However, melanoma under the toenails is somewhat rare—it accounts for 3 percent of all melanomas in people with lighter skin and 30 percent in those with darker skin. 

Fungal infections can also sometimes cause blackened toenails. In this case, the nail might also get thickened or brittle. Treatment may not be necessary for mild cases, but the Centers for Disease Control and Prevention (CDC) recommends speaking with your healthcare provider about it so you get the right treatment. 

Remember, it’s never a bad idea to talk to your doctor about any concerns, including a black toenail.

The Takeaway

Runner’s toe (aka subungual hematoma) is the result of exposing your toenail to lots of pressure or friction, leading to a bruise under the nail. It’s common among long-distance runners, but can occur in other athletes, too (or simply when you stub your toe or drop something heavy on your foot).

If you’re prone to chronic runner’s toe, it might be something you have to deal with for as long as you continue to run, bike, or walk. But you can try bigger shoes, seamless socks, baby powder, or wrapping your toes with tape to help ward off the condition when you know you’ve got big workouts coming up. 

Fortunately, even though you might not love the aesthetic of bruised or missing toenails, that’s usually all the problem typically is: aesthetic. “The nail is really an archaic structure,” Dr. Mendeszoon says. “The reality is humans really don’t need toenails.” And for what it’s worth, some runners see black or missing toenails as a badge of honor, almost like a medal for all those hard miles they’ve run. Embrace it! 

However, in the instance that your runner’s toe is causing you major discomfort, if the bleeding just won’t seem to stop, or if the dark spot under your toenail gets bigger or changes in shape, book a visit to the podiatrist—they’ll likely be able to help you out so you can get back to your workouts pain-free.