Fungal nail infections, or onychomycosis, are more common on the toenails than the fingernails. Onychomycosis tends to run in families because of an inherited tendency, but not everyone is susceptible. It is rare in children unless one or both parents are infected.
A dermatologist may take samples from the nail in order to properly identify and treat the problem. A scraping of the nail is treated with a chemical called KOH which allows it to be examined under a microscope. Sometimes, the scrapings from under the nail can be used to culture the material to see what grows and identify it. Other conditions such as nail psoriasis or allergic reactions to nail polish, hardeners, or acrylic nails may look like fungal infections, but they are not. These tests help make the proper diagnosis.
Fungal infection of the nails is also important in people who have other diseases such as diabetes, and those who have had their immune system suppressed. Patients who are HIV+, have AIDS, cancer patients, particularly those taking anti-cancer medications, and transplant patients who are also taking drugs which suppress the immune system, should be treated to prevent future health problems.
Topical antifungal creams, lotions, gels, and lacquers may be used, however, it is difficult for them to penetrate the nail.
Oral medicines like itraconazole, terbinafine, and fluconazole are used, and may require monitoring with blood tests. These are usually avoided in patients with a history of liver problems such as hepatitis and are not given to pregnant or nursing women. These new internal treatments are very safe when monitored by the dermatologist. In general, toe and fingernail fungus usually requires pills except in very mild cases.
Debridement or removing the infected part of the nail may enhance the effectiveness of the treatment. Dissolving or surgically removing the nail if the nail is thick and deformed may be helpful in a few situations, and used only if the infection is very severe.