Nail fungus, or onychomycosis, is a condition that occurs when a microscopic fungus enters either a fingernail or toenail. Fungal infections occur in toenails more often than in fingernails.
Anyone can get nail fungus, but infections are more common in people over the age of 60. For people who have diabetes or a weakened immune system, nail fungus can present serious risks.
Usually, nail fungus occurs when fungus enters the nail through a small trauma (cut or break) in the nail. Nail fungus is not caused by poor hygiene. Nail fungus can be spread from person to person. It may be hard to determine exactly where or how a fungal infection is acquired. However, a warm, wet place (for example, a locker room) is a good place for a fungus to grow.