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Core Knowledge


How to Treat Runner's Toe


Runner’s toe is also called “tennis toe” or “skier’s toe” because it happens most often among runners, tennis players and skiers. Some people simply call it “black toenail” because of its ugly appearance. You’ll know you have it when you see that there has been bleeding under a toenail accompanied by pain. It’s not a serious injury, but it hurts. It can also prevent you from participating in some sports, and it can take days, weeks, or even months for the blood to work its way out from under the toenail. That makes the area under the toenail a perfect environment for infection.

tangywolf / flickr


How It Happens

This condition develops because of repeated pressure downward on the toenails or irritation between the toenails and the shoe. If your shoes are too tight, the constant pressure damages the toe and toenail. If they're too loose, the ongoing movement of the foot inside the shoe results in the same condition. If your toenails are too long, they're a target for getting banged around inside your shoes. Also, your feet may swell during hot weather and become more susceptible to shoe/toe friction. Finally, you may sustain runner’s toe by taking a blow on the top of the foot. But whatever the cause, the skin bruises and bleeds underneath the nail. If enough damage has occurred, part or all of the toenail may fall off. 

By the Numbers

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Less than one in one hundred athletes develop runner’s toe.

Percentage of marathon runners who sustain a lower extremity injury, but only a fraction of those injuries are diagnosed as runner’s toe.

Who’s At Risk

Runners are most susceptible, and distance runners are at a very high risk. Serious (fast) walkers, dancers, tennis players, and skiers are in a higher-than-normal risk group because they are constantly jamming the front of their foot forward and into the toe box of their shoes or boots.


  • Slight irritation is the best-case scenario
  • Pail (sore toe) is found in more serious cases
  • Bleeding under the toenail
  • Reddish, brown, black, or bluish appearance of the toenail
  • Loss or partial loss of the toenail in more serious cases
  • Separation of the toenail from the toe bed (skin)

Initial Treatment

  • In minor cases, the injury resolves itself within a day or two of rest.
  • Clip the toenail so it does not make contact with the shoe.
  • Wear a shoe with a bigger, wider toe box to prevent further irritation.
  • Tape a partially torn toenail (for protection) until a new nail begins to form.
  • Don’t pull the damaged nail off. It may fall of on its own.
  • A health care provider might have to drain blood through the toenail with a specialized instrument.
  • See a doctor if the pain persists or you see signs of infection like redness, swelling or pain that persist longer than a few days.


Comeback Strategy

“Don’t let your runner’s toe lead to a more serious injury,” warns Anna Hartman, a physical therapist at Athletes’ Performance in Phoenix, Arizona. “Be aware of the pain your toe is creating and try not to let it change how you walk or move. Often, a sore toe can lead to a change in gait pattern, which changes the force all the way up the kinetic chain. These changes can lead to knee pain, hip pain and back pain.”

  • Take at least a day or two off.
  • Keep the area as clean and dry (no cotton socks) as possible.
  • Return to training as soon as you can stand the discomfort, assuming you have made the necessary adjustments to prevent your toes from constantly rubbing against the top of your shoes.

How to Avoid It

  • Wear running shoes that are at least one-half size larger than your street shoes.
  • Trim your toenails regularly and straight across, but not so short that the remaining nail or nail bed is exposed to shoe/toe irritation.
  • Keep your feet as dry as possible (wear socks than wick moisture away from the skin).
  • Lace your shoes more tightly if you run downhill regularly to prevent excessive movement and friction.

Jim Brown, Ph.D. has written 14 books on health, medicine, and sports. His articles have appeared in the Washington Post, New York Post, Sports Illustrated for Women and Better Homes & Gardens. He also writes for the Duke School of Medicine, UCLA School of Medicine, Cleveland Clinic and Steadman-Hawkins Research Foundation.

Tags: Triathlon, Foot Pain, Injury, Running


  1. Anna Hartman, MS, ATC, CSCS, Manager, Performance Physical Therapist, Athletes’ Performance, Phoenix, Arizona
  2. American Running & Fitness Association
  3. Running Injury Free, by Joe Ellis
  4. TheRunningAdvisor.com
  5. University of Michigan Health System