Runner’s Toe – Symptoms, Treatments, and Prevention


For runners, a black and bruised toenail isn’t always a bad thing. In running circles, a black toenail is like a medal or a badge of honor! 

Once you’ve had your first runner’s toe, you can consider yourself a true member of the running community. Although it is unsightly, especially on those beach days.

If you are not sure what it is or what to do if you have it, here are the symptoms, treatment, and prevention of runner’s toe.

What is a Runner’s Toe?

Runner’s toe—also known as jogger’s toe—doesn’t affect the toe itself, but the toenail and nail bed.

Runner’s toe is when the nail turns black due to bleeding underneath the toenail—on the nail bed. The bleeding under the toenail is known as a subungual hematoma, which is when the nail bed is injured and blood vessels break open.

The toenail becomes discolored—black and blue—due to bruising, or from blood—like a blood blister—that pools under the toenail, which turns blackish as the blood dries.

Subungual hematoma can range from mild to severe, where the toe may feel tender to the touch or it may be very painful.

The main cause of runner’s toe

Runner’s toe is most often caused during the push-off phase of your gait, where your toes hit the front of the shoe—toe box—while the upper of the shoe places downwards pressure on the toenail, especially if you’re wearing ill-fitting shoes. This causes repetitive trauma—or microtrauma—to the toenail, which causes bruising or bleeding.

When running downhill, these microtraumas add up and often result in the nail plate separating from the nail bed. This leads to bleeding and the forming of a blood blister. There’s also an increase in blood flow and this can also cause your foot to swell. If you don’t have enough space in the toe box, your toes will be in constant contact with the front of the shoe; this can make the problem worse.

Wearing socks that are too thick can also place pressure on the toes, which can lead to a subungual hematoma.

Subungual hematoma can be made worse if a runner already has foot conditions like hammer toe. A runner may also experience runners’ toes if they don’t use the correct lacing techniques.

Runner’s toe usually occurs either in the big toe or the second and third toe. While it may sound like it’s painful, runners may not even feel it happening and only notice it when they take their shoes off.

What are possible complications?

In most cases of runner’s toe—black toenails—it’s often painless and the toenail will eventually fall off. But there are times when a blood blister will form under the toenail and around the toe.

This will push the toenail upwards, which can cause tears in the nail bed, leaving it vulnerable to infections. After all, fungi thrive in moist conditions like sweaty socks. It would be best to use topical cream on the toe before and after running to prevent any infections.

As the toenail starts to lift, you may be tempted to pull the nail off, but it’s best if you leave it to fall off naturally. If you pulled it off, you could damage the nail bed which can lead to scarring and your new toenail could be deformed when it grows back.

There are other reasons as to why a person could have a black toenail. Some reasons are because an individual has an underlying condition. A fungal infection could make the nail thicken and it can turn a very dark grey, blue or black color—not all fungal infections are going to turn the nail yellow.

If you’ve noticed a black spot—or black vertical line—close to the cuticle under your nail that doesn’t go away, then you may want to visit the doctor and have it checked out for melanoma.

If you’ve increased your mileage, running lots of hills or trails, then the most likely cause of your black toenail is running.

Symptoms of Runner’s Toe

While you’re running, you probably won’t notice any discomfort in your toes. But once the shoes and socks are off, you’ll notice swelling around the head of the toe.

The tip of your toe may feel tender and as the pressure of fluid builds up under the nail you may experience some pain, especially when pressure is applied to the toe. This should ease up over the next day or two.

Some runners may even experience sharp, throbbing pain under the nail bed, which is caused by the pressure of the blood pooling under the nail. Part or all of the nail will be discolored, which can range from red to black and blue—like a bruise—to a dark black-purple color.

The nail may start to lift up from the pressure of the blood underneath it, and in most cases, the nail will become thick and brittle before it falls off. You’ll start to notice that the nail does loosen over the next few weeks before it falls off.

If the redness and swelling around the toe head doesn’t go away after two or three days, then it could be a sign of infection. If an infection has developed then you may also experience sharp pain in the toe, a bad smell, and swelling as well as oozing pus. Some people may even feel feverish from the infection.

To prevent infection, make sure that you run with socks that are moisture-wicking and soak your feet in saltwater for 5 to 10 minutes a day. Also, make sure that your feet remain dry throughout the day.

When Does Runner’s Toe Heal?

It can take 1 to 5 months for the toenail to fall off and then it can take up to a year for the new nail to grow out.

This doesn’t mean that your running has to come to a halt; you can still run with black toenails but you should take precautions that will help your toes to heal.

The first thing you should do is change the size of your running shoes and go up a half size. This will accommodate your feet when they swell, while giving your toes some wiggle room.

Make sure that your socks are thin and that they do a great job of drawing moisture away from the skin, as this will prevent your foot from sliding in your shoes.

You can also reduce your mileage, as this will reduce the amount of repetitive microtrauma that your toenails will be experiencing with each foot strike.

Pay attention to your running mechanics, as you may find that your toes are hyperextended during the push-off phase. This could be putting more stress on your toes, which can lead to black toenails.

How to Treat Black Toenails

1. Mild cases

In mild cases, the blood blister under the nail may be smaller and won’t cause any pain or lifting of the nail—it would be more cosmetic. There would be no need for treatment and you can let your nail grow out, which could take between six and nine months.

2. Worse cases

In more severe cases of runner’s toe, there will be more blood under the nail which places more pressure on the nail bed, leading to sharp, throbbing pain.

In this case, you may have to release the pressure, and it’s better to do this within the first 24 to 35 hours before the blood dries. That being said, it’s best to visit your doctor as they could recommend trephination.

The doctor will make small holes through the toenail so that the blood can be released. While there are runners who have done this by themselves at home, it’s always best to have your doctor do it. This will prevent any bacterial or fungal infections or any possible injury and scarring to the nail bed.

Sometimes having your doctor perform trephination can prevent the nail from falling off in a few months.

Preventing Runner’s Toe

There are steps you can take to prevent runner’s toe, and the first should be to keep your toenails trimmed. When you do cut your nails, make sure to do it in a straight line as this will also prevent ingrown toenails, which can cause pain.

Make sure that your running shoes have at least a thumb’s width of space—a half size up—between your toe and the front of the shoe. Your feet will swell when you run more, so on hot days having some space in the toe box will accommodate the swelling.

The arch support of the shoe should align with your arch, which will help keep the natural alignment of your foot as well as disperse your bodyweight evenly.

You may even want to try running shoes that have a smaller heel-to-toe drop, as this will place less stress on your toes and prevent your foot from sliding forward in the shoe. Wear socks that are thin and moisture-wicking. This will help prevent friction and pressure on the toes throughout the gait cycle.

With everyone’s foot being different, you may have to experiment with different lacing techniques like the runner’s knot—heel lock—to help keep your foot from moving forward when you run.

Runners can also use silicone toe pads—toe caps—that will prevent microtrauma to the toes when they come into contact with the toe box. Toe caps will also relieve the downwards pressure that the upper of the shoe may place on your toes.

What to do if your toenail falls or rips off

In most cases, the toenail will fall off without any pain or bleeding. But should your nail rip off, it will create tears in the nail bed, which will bleed. Should this happen, you should apply pressure to the toe until the bleeding stops.

Apply an antibiotic ointment to the toe and then bandage your toe. You can use the antibiotic ointment twice a day until the wound has closed. This will allow it to heal while preventing infection.

Even if the toenail falls off without any bleeding, you should apply antibiotic ointment to the exposed nail bed. This skin will be very sensitive for the first few days and to prevent any chaffing or irritation you can put a cotton wool ball over the toe and wrap it with a bandage or band-aid. This will prevent your socks and the tops of your shoes from rubbing against the nail bed.

Make sure to check your toe for any signs of infection on a daily basis. If you do experience severe pain, redness or swelling around the toe, a bad smell or even pus, then you should see your doctor. If an infection is left untreated, it could lead to more severe conditions like blood poisoning or even gangrene.

Photo of author


Ben is an avid road and trail runner, and has completed multiple marathons and ultras. A former running store owner, he now shares his knowledge and experience writing these articles.