Painful, black toenails after running: this is 'runner's toe' and how you can prevent it

Runners toe, scientifically known as a subungual hematoma, is a common injury characterized by blood pooling under the toenail. Sports physician Sandra Chung explains that this condition typically results from repetitive trauma, such as feet sliding forward in shoes during long-distance running or soccer matches, causing the toes to strike the front of the shoe repeatedly. While often associated with marathon runners and athletes, it can also stem from direct impact injuries. Although the condition is generally harmless, the trapped blood creates significant pressure under the nail, which can be quite painful.

Prevention centers on ensuring proper footwear that avoids uncomfortable pressure points, though experts advise against using tape as it offers little protective benefit. Maintaining short toenails and improving core and leg stability may help athletes sustain better form and reduce stress on the feet. If pain persists, cooling the area or consulting a professional to relieve pressure through the nail may provide relief. Because the discoloration persists until the nail fully regenerates, recovery can take several months.