Onychomycosis accounts for up to half of all nail disorders. It is the most common nail disease, affecting about one in seven North American adults. Less commonly, children may also develop it. The risk increases with advancing age, affecting about one half of people over 70 years.
Toenails are more often involved than fingernails. Infection of both at the same time is not common. Onychomycosis is uncommon in developing nations where open footwear is worn.
Certain factors make onychomycosis more likely. Advancing age, being male, having a weakened immune system, wearing tight footwear, and using shared shower areas can all increase risk.
Contrary to popular belief, those with diabetes are not particularly at risk. However, diabetes may affect the course of infections once they start.
Fungi can pass directly from one person to another. It can also transmit indirectly on objects. Some spores can survive in the environment and cause infection for up to five years. For this reason, it is wise to avoid walking barefoot in locker rooms and shared shower areas.
Fungus infects the nail in different ways. Most commonly, it spreads from skin to invade the under-surface where the nail meets the nail bed. Sometimes the fungus attacks the nail’s surface, then the nail bed.
Onychomycosis generally does not cause any symptoms. People usually see their family doctor or dermatologist because they do not like the way their nails look. Toenails sometimes become painful, making it hard to walk. Rarely, diseased nails may cause other infections.
The pattern or effect of a nail infection depends on the part of the nail and the fungus involved. Most often, diseased nails are discoloured and look white to brownish-yellow. They become noticeably thicker, and debris collects under the nail. Sometimes the nail may rise from the underlying nail bed. It may also roughen and crumble easily.
Once in place, the infection does not usually clear up by itself. Instead, it may spread to involve many nails.
Since other conditions can affect nails, your doctor will want to confirm fungal infection before starting therapy. Many other non-fungal skin conditions affect nails, including psoriasis and lichen planus. Elderly people often develop thickened nails. Since this thickening is not caused by infection, medication will not help, so treatment can be costly and cause possible side effects. It is important for your doctor to confirm a fungal infection before starting treatment.
Diagnosis of onychomycosis can be made by scraping the nails to look for fungal infection under the microscope. This takes only minutes and usually confirms whether it is present. (However, sometimes the fungus can be missed.) Since seeing it under the microscope does not tell the actual type of fungal species involved, the doctor often needs more detail to treat it.
Fungal infections are also diagnosed by culture. Your doctor sends a scraping of the diseased nail to the lab. This test identifies the exact species of fungus causing the infection. A culture result usually takes about four weeks, although repeated cultures may be needed to prove an infection.
Treatment depends upon the pattern and type of infection, the thickness and number of involved nails, and on the patient. Fungal infection is treated for both cosmetic and medical reasons. The goal of antifungal therapy is to make nails look normal again. This may take as long as 12 to 18 months for toenails.
Good nail hygiene includes keeping feet cool and dry, trimming nails, and wearing footwear that fits properly. Using topical antifungals and antifungal powders can help prevent further infections once the nail infection is treated.
Topical treatment only helps mild infections, although those unable to take oral medications might also try them. Ciclopirox (Penlac™) is a topical anti-fungal that looks like clear nail polish. It is applied nightly for 48 weeks after trimming the nails. It is seven per cent effective in curing and clearing up nails when used for a mild or moderate disease. Users avoid the side effects of oral medications and possible drug interactions. Most people do not have problems with it. However, the cure rate is low. Although Penlac™ is fairly expensive, it is covered by some drug plans.
Several different oral antifungals are available to treat nail infections. The medication your family doctor or dermatologist will prescribe depends upon the type of fungus involved. Treatment usually lasts for three to four months, at which point new, normal nail growth should appear. These medications are generally well tolerated.
Terbinafine (Lamisil™) is taken daily for three to four months. Side effects, which may affect about 10 per cent of users, can include nausea, diarrhea, mild abdominal pain, and taste changes. Side effects will disappear when the medication is stopped. In rare cases, liver toxicity can occur. For this reason, liver function tests may be done every four to six weeks during treatment.
Itraconazole (Sporanox™) is an alternative oral antifungal. It can be taken either daily or as a double dose daily for a week each month for three months. Side effects are uncommon, but include minor stomach upset and headache. Less than one percent of the time, liver function tests can go up, so again, liver function will be monitored during treatment. This medication is generally not as effective as terbinafine.
Sometimes, nails that resist treatment can be surgically or chemically removed.
Fungal infection of the nails is common. Proper diagnosis is essential. Several treatment options are available, depending upon the severity of the condition and on your preference.