what makes toenails turn black
When Toes Turn Dark. Nails change colors for multiple reasons. The most common culprit for a black toenail is blood under the hard tissue. Damage to the end of the toe causes blood to leak through the nail bed and stain the keratin a dark color. This is also known as a subungual hematoma, or a bruise under the nail.
A Black Toenail Can Be a Big Problem. Abnormal color change is usually a warning sign of damage. Sometimes the problem is relatively minimal, like a light bruise on the surface of the skin. Other times, the discoloration warns of dramatic problems that need to be addressed, like someone turning blue when choking.