Onychomycosis

Onychomycosis is a fungal infection of the toenails.

Onychomycosis usually occurs in people with a fungal infection of the skin between the toes. Injury to nails or to the surface beneath nails (the nail plate) and moisture around the toes makes the development of onychomycosis more likely. Onychomycosis is common among older people, especially among those with diabetes.

Symptoms and Diagnosis

A nail affected by onychomycosis becomes white or yellow. It can thicken and develop a coarse, irregular surface. The nail can partly crumble or partly separate from the underlying nailbed. The nail may curl up or down (gryphosis).

Onychomycosis can usually be diagnosed on the basis of the nail's appearance. However, laboratory testing of material scraped or swabbed from the surface underneath the toenail may be done to confirm the diagnosis.

Prevention and Treatment

Keeping feet dry and treating athlete's foot may help prevent onychomycosis.

Although it rarely causes serious health problems, onychomycosis can trouble older people or their caretakers. The nails can become difficult or nearly impossible to trim. Using special clippers or other tools, a nurse, doctor, or foot doctor (podiatrist) can provide nail care. Onychomycosis is a special problem for people with diabetes or poor blood flow to the foot, for whom infections of the toes or feet can have serious consequences.

Most people do not need antifungal treatment. Antifungal drugs often fail to cure the infection, but the drugs may help to suppress the infection and improve the appearance of the affected nails. The two drugs that are used, itraconazole and terbinafine, are taken by mouth. Sometimes drug therapy helps in as little as 3 months, but for most people, especially people with poor blood flow to the foot, treatment must be continued until the nails grow out, which can take up to a year in older people. Because itraconazole and terbinafine may interact with other drugs and may cause side effects, treatment is worthwhile only if onychomycosis causes health risks or bothersome symptoms. Both itraconazole and terbinafine are available as less expensive creams, but they do not help when they are applied to the surface of infected nails.

A compromise approach, which is far safer but much less likely to cure the infection, is painting the nails daily with an antifungal (ciclopirox) solution. Most often, this treatment has little or no effect. When this solution does help, there is a very good chance that the infection will return soon after treatment is stopped. The spaces between the toes and the bottoms of the feet can be treated with an antifungal cream or powder to reduce the likelihood of reinfection of the nails.