Updated August 23, 2012
Written or reviewed by a board-certified physician. See About.com's Medical Review Board.
Our nails are thickened extensions of the top layer of our skin and are made of the same tough protein, called keratin. The nail grows out from an area below the skin known as the matrix and is intimately connected to the blood vessel and nerve-rich nail bed beneath it.
Our toenails are subject to a great deal of stress, whether it's rubbing against shoes, a stubbed toe, or the constant presence of bacteria and fungi (picture the environment inside a shoe). In light of these conditions, there are three common toenail problems that we often see.
Toenail fungus, or onychomycosis, is a slow-growing infection of the nail and skin beneath it. It is usually caused by the same type of fungi that causes athlete's foot; in fact, people who are prone to athlete's foot may also be susceptible to toenail fungal infections.
Toenail fungal infections are characterized by a white, brown, or yellow discoloration of the nail along with eventual thickening and debris. It can be a difficult infection to treat because of its location beneath the nail. The most successful treatment option has been oral antifungal medicine, which has the downside of possible side effects. Other treatment options are available and are continually evolving.
An ingrown toenail occurs when the edge of the toenail, usually the big toe, grows into the skin next to it (lateral nail fold). This results in pain at the side of the toe and often redness, swelling, and discharge characteristic of an infection. The ingrown aspect of the nail is usually unseen because it is below the skin. Risk factors include improperly fitting shoes or socks or abnormal toe shape.
Treatment involves having the ingrown aspect of the nail removed, which often results in quick relief from pain. It can be a recurring problem, however.
Injury to the nail's growth center, or matrix, can result in a number of possible changes to the nail. Trauma to the toenail can be chronic and repetitive, such as rubbing against the shoe when walking or running. It can also be an acute injury, such as stubbing your toe or dropping an object on it. Changes that can occur include blood and bruising beneath the toenail, toenail thickening, or toenail loss.
Toenail trauma can result in secondary bacterial or fungal infection if any part of the nail has come loose. Acute trauma may also result in a fracture of the bone beneath the nail, to which the nail is in close proximity.
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