Causes of Black Toe
The most common cause of black toe is repeated trauma from the toe banging against the end of the shoe. Since the big toe is usually the longest toe, the banging produces bleeding and bruising of the nail, causing it to become discolored (often blue and then black). The banging of the toe against the front of the shoe or boot is usually a sign that the shoes are too short, or that they fit too tightly and do not allow sufficient room for the feet to move dynamically during walking and running.
Other causes may include the following:
- Sudden trauma or injury to the toe or toenail.
- Fungal infection.
- “Morton’s toe,” a condition in which an individual’s second toe is longer than the big toe.
- Rarely, a subungual (occurring under the toenail) melanoma, a form of skin cancer.