Your Toenails Know More Than You Do: The Hidden Health Clues Below the Surface

A black or dark brown toenail is most commonly caused by trauma, where blood pools under the nail plate, known as a subungual hematoma. This is usually harmless and grows out over time. However, if a dark streak runs from the cuticle to the tip and is not related to an injury, it must be evaluated immediately, as this can be a sign of subungual melanoma, a rare but serious form of skin cancer.