Nail Fungus (Onychomycosis): Symptoms & Signs

Medically Reviewed on 9/10/2019

The term fungal nails, medically known as onychomycosis, refers to a fungal infection of the toenails or fingernails. Fungal infection of the nails may cause changes in the nail itself and its appearance, including symptoms and signs such as

Fungal nails may appear brittle, broken, and lifted or separated from the nail bed. Changes in the nail appearance are typically the first signs and symptoms of fungal nails. The condition may also cause pain and disfigurement in some cases, although this is not common. In severe cases, fungal nails can cause problems with standing, walking, and exercising. Both oral and topical antifungal drugs may be used in treatment.

Causes of fungal nails

A number of conditions can increase the risk that fungi infect the nails. Fungus that is caught from moist, wet areas are common causes in healthy people. Communal showers, such as those at a gym or swimming pools, are common sources. Visiting nail salons that use inadequate sanitization of instruments (such as clippers, filers, and foot tubs) is another way that the infection may be spread. Living with family members who have fungal nails is another risk factor. Wearing tight-fitting, sweaty shoes associated with repetitive trauma to the toenails occurs in many athletes and increases the susceptibility to fungal nails. People with athlete's foot are more likely to have fungal nails, since the causative fungus may infect the toenails. The elderly and people with suppressed immune function are also at risk.

Trichophyton rubrum is the most common type of fungus to infect the nails. This fungus is a dermatophyte, meaning that it is a fungus that infects skin and nails.

Other nail fungus (onychomycosis) symptoms and signs


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Tosti, Antonella. "Onychomycosis." July 13, 2017. <>.