A fungus infection, or onychomycosis, is the most common type of nail disease. The infection causes nails to become thick, discolored, and brittle. Often, the nail crumbles or separates from the nail bed.
Studies suggest that as many as 8 percent of all adults—and 20 percent of adults over the age of 40—have fungal nail infections. Men are more likely than women to develop this unsightly and often painful nail condition, and individuals become more susceptible as they age.
Some 90 percent of nail infections are caused by a type of fungi known as a dermatophyte, although yeasts and molds can also infect and destroy nails. The most common dermatophytes involved in nail infections are Trichophyton rubrum, Trichophyton mentagrophytes, and Epidermophyton floccosum.
Fungi are microscopic organisms that like warm, moist, sunlight-free environments. They invade your skin through tiny cuts and spaces around or under your nail. They then live and grow in the layer of dead skin around the nail—or in the nail itself.
Some risk factors for nail infections are difficult, if not impossible, to change. You’re more likely to develop a nail infection if you’re over the age of 40, for example. Other risk factors include a family history of fungal infections and living in a hot, humid climate. Individuals with underlying health problems that weaken the immune system or that impair blood circulation, such as diabetes, cancer, and AIDS, are also at greater risk for nail infections.
But other risk factors can sometimes be avoided, including the following:
- Working in a humid or moist environment
- Wearing socks and shoes that keep the feet damp
- Walking barefoot in gym locker rooms and around community swimming pools
- Sustaining an injury to a nail or to the skin around the nail
- Sharing nail files, emery boards or nail clippers (including “sharing” your own nail implements by using them on both infected and non-infected nails)
- Having manicures and pedicures in nail salons that don’t properly sanitize their equipment