Onychomycosis

Onychomycosis is a fungal infection of the nails.

The fungus can be acquired by walking barefoot in public places or, most commonly, as part of an infection called athlete's foot (see Section 18, Chapter 212). Older people, people who have diabetes, and people with poor circulation to the feet are particularly prone to this type of fungal infection.

Mild infections may produce few or no symptoms; in more severe infections, the nails turn white to yellow-brown in color, thicken, and detach from the nail bed. Usually, debris from the infected nail collects under its free edge. A doctor may confirm the diagnosis by examining a sample of the nail debris under a microscope and culturing it to determine which fungus is causing the infection.

Fungal infections are difficult to cure, so treatment depends on how severe or bothersome the symptoms are. The nails should be kept trimmed very short to minimize discomfort. For mild to moderate infections of the nails, ciclopirox, an antifungal drug that is placed in a nail lacquer, may be effective. The person applies the lacquer directly to the nail; the drug penetrates the nail plate to reach the infected nail bed below. Because ciclopirox has minimal to no side effects, it may even be preferred to antifungal drugs that are given by mouth.

Other antifungal drugs, such as griseofulvin or terbinafine, are taken by mouth and may improve the condition; occasionally, these drugs completely cure it. Terbinafine acts more quickly than griseofulvin, is more effective, and causes fewer side effects. Alternative antifungal drugs include triaconazole and fluconazole.