What to Know About Runner’s Toe

Medically Reviewed by Tyler Wheeler, MD on February 28, 2024
3 min read

Athletes and runners often get a condition called runner’s toe, which is a blackened toenail caused by repeated strain on your foot. It's not dangerous, but it can be very painful, and there are ways to prevent it. 

Runner’s toe happens when your toenail turns black from the stress of running. When your toe repeatedly rubs on or slams into your shoe, it can cause stress to your nail. This leads to bleeding under your nail, which starts to look black.

You may also hear it called:

  • Runner’s toenail
  • Jogger’s toenail
  • Tennis toe
  • Subungual hematoma

Bleeding under your nail usually happens when you hit your toe hard or drop something on it. Runner’s toe is like lightly hitting your toe over and over again.

Runner’s toe often affects runners, as the name suggests, but you can also get it if you take part in activities like:

  • Rock climbing
  • Soccer
  • Squash
  • Racquetball
  • Tennis

In soccer, kicking the ball over and over again can stress your nail and cause blood to leak from the vessels underneath. Sometimes, kicking it too hard with the top of your toe can do this, too.

For tennis and squash players, the constant starting and stopping and the sudden thrust against your shoe can cause stress to your toe. If you play these sports often, over time, this can damage your toenail.

Rock climbers often wear tight shoes and repeatedly press their toes into holds. This pressure can cause runner’s toe.

Runner’s toe usually happens over time. Symptoms include:

  • Dark red toenail, which is usually new damage
  • Black toenail, a sign of an older damage
  • Loose toenail
  • Pain
  • Blood blisters
  • Pressure beneath your toenail
  • Loss of toenail
  • Trouble walking
  • Trouble wearing shoes

Runner’s toe often happens on your big toe, as it sticks out farther than your other toes, but it can affect any toe. Soccer players tend to have runner’s toe on their first and second toes. 

It’s common to have severe pain that makes it hard to be active. This is usually caused by the pressure building up under your nail. It can even cause your toenail to lift off the nail bed. 

If your toe and nail don’t hurt, you probably don’t need to do anything about it. The nail might fall off on its own and grow back.

If your toe starts to hurt or you have trouble walking or doing other activities, see your doctor to rule out broken toes or other problems. If you have runner’s toe, they will do a procedure called nail trephination.

Nail trephination involves draining the pooled blood by drilling a small hole into the nail with a heated needle or carbon dioxide laser. They will give you local anesthetic first so it doesn’t hurt. 

The nail might fall off after treatment, but this happens because of the blood collection rather than the needle. Your nail will grow back, but if you’ve had damage to your nail bed, it may be deformed. This can also happen if it falls out on its own.

If you’re an avid runner or athlete, there’s a good chance your black toenail is runner’s toe. Black toenails can be signs of other diseases, though, so it's a good idea to have your feet examined.

A black toenail can also be a sign of a:

  • Fungal infection
  • Chronic ingrown toenail
  • Benign bone tumor called subungual exostosis
  • Melanonychia striata
  • Cancerous tumor

Runners tend to have damp feet from sweat. This can make you more likely to get fungal infections.

Other causes like cancer and other tumors are rare.

The best way to prevent runner’s toe is to use the right shoes. Make sure they fit your foot properly and aren’t too tight on the toes. You should have a half-inch between your big toe and the end of your shoe.

You should also be able to freely wiggle your toes. If your toes are cramped in your shoes, you’re more likely to have problems.

It’s a good idea to find a shoe specifically designed for your sport. These shoes are designed with these problems in mind. 

You can also keep your toenail trimmed so they don’t rub on your shoe.