Runner's Toe/Black Toenail - Because of repeated trauma -- such as the toenail repeatedly hitting or rubbing against the top of the shoe, the front of the shoe, or both -- a toenail can take on a black or deep purple appearance when blood collects under the nail. Black toenails are usually caused by shoes being too tight and/or too short. Also, bruising can occur if your foot slides back and forth inside the shoe. Properly fit shoes are essential.

Recommendation: Consider any shoe that matches the shape of your foot. Footwear must be long enough and deep enough to avoid repeated pressure on the toes.