A black toenail or Subungual Hematoma is a common problem resulting from direct trauma and impact to the toe or overuse. The toenail turns black from blood between the nail and the skin, which may cause pressure and a throbbing sensation under the nail. This toe injury normally heals by itself but if it is more severe, further treatment may be necessary.
A black toenail can also be caused by repetitive rubbing against the inside of a shoe, for example in the case of long distance runners, which is frequently known as Jogger's Toe. This is more common in ultra distance runners and soldiers who undertake long marches.
Signs and symptoms
The toenail appears black due to blood between the nail and the nail bed. The patient may feel a throbbing pain as the pressure increases under the nail with pulse. Eventually the nail may loosen from the nail bed and eventually fall off.
Treatment for a black toenail
There are two main treatments for a black toenail; trephining or nail removal.
Trephining is the process of making a hole in the nail, using a heated instrument about the size of a paperclip to pass easily through the nail.
The purpose of trephining is to relieve the pressure and pain under the toenail. The nail is then covered with a small dressing to prevent infection.
Nail removal is used in more extreme cases where the nail becomes misshaped or disrupted by the hematoma, or if there is a more serious underlying injury such as a fracture of the toe. Anaesthetic is not usually supplied, but sometimes nerve blocks are used.
Subungual Hematomas usually heal by themselves with little incident other than the pain, but can become infected or disrupt the nail.