Subungual Hematoma: What Causes Black Toenail in Runners?

What is Subungual Hematoma or Black Toenail?

Subungual hematoma also known as Black Toenail is a condition where direct trauma or injury to the nail bed causes blood to accumulate underneath the nail and results in black appearance of the nail. It is a frequent problem in runners due to recurrent rubbing or friction of the toe inside shoe. It is also known as “jogger’s toe” or “tennis toe.”

Black Toenail or Subungual Hematoma

What Causes Black Toenail in Runners?

Subungual Hematoma or black toenail is caused by trauma or injury to the toe, especially seen in runners. The downward pressure during running causes the nail plate to separate from the nail bed. As this pressure continues it causes more damage resulting in bleeding and accumulation of blood under the nail plate causing its black appearance. The nail becomes thick, brittle and disfigured. As the time passes, the affected nail grows out and is replaced by a new, normal nail plate. In some cases, there is extreme pain in the toe which warrants a surgical drainage. Subungual Hematoma or Black toenails are very common among runners, particularly those training for long-distance races. The toenail becomes black in color, thick and brittle and eventually falls off and a new nail grows back in. Runners doing a lot of downhill running are at higher risk for black toenails as their toes are continuously rubbing against the front of their shoes. Black toenails are more common in warm weather as the feet swell more in the summer.

Other Causes of Subungual Hematoma or Black Toenail:

  • Repeated rubbing of the toe against the anterior part of shoe.
  • Repeated trauma to the toe.
  • Ill-fitting footwear.

Signs and Symptoms of Subungual Hematoma or Black Toenail

  • The increased pressure beneath the nail due to accumulated blood causes throbbing pain in the toe.
  • Toenail is black in appearance due to pooling of blood between the nail and nail bed.
  • If redness is present, it is an indication of infection and doctor should be consulted immediately.
  • The nail becomes thick, brittle, and loose and ultimately falls off.
  • Toe Pain while running.

Treatment for Subungual Hematoma or Black Toenail

The Two Main Treatments Options for Black Toenail are Trephining and Nail Removal

  • Trephining the Black Toenail: Trephining is the process where a hole is drilled into the nail to release the accumulated blood and decrease the pressure. A small dressing is applied to the nail to ward off infection.
  • Complete Nail Removal Treatment for Subungual Hematoma or Black Toenail: In severe cases where the nail is disfigured or the toe is fractured, the nail is removed completely. Most of the times anesthesia is not used, but in some cases digital nerve blocks is used.
  • Subungual hematomas heal by themselves over the time and are generally not a serious condition.

Prevention of Subungual Hematoma or Black Toenail In Runners

  • Suitable running shoes of correct size should be worn.
  • Feet should be kept dry during running
  • Drymax sports socks or wicking socks should be worn instead of cotton socks.
  • The shoes should be laced tighter at the front part of the shoe in case of downhill running.
  • It is advisable to trim your toenails before running to prevent the nails from rubbing the inside of the shoes which can cause bleeding underneath.
  • Sudden changes to your training regime, like sudden increase in the distance run daily can trigger black toenail especially if you are a beginner in marathon running. Having a gradual increase can prevent Subungual Hematoma or Black Toenail.

Also Read:

Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:June 20, 2018

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