Fungal infections of the nails are also known as onychomycosis and tinea unguium. The fungi in question are usually those that cause athlete’s foot – a common infection of the skin of the feet. In athlete’s foot the fungi live in the keratin that makes up the outer layer of the skin, but they can also invade the hard keratin of which nails are made. When this happens, the result is a fungal infection of a nail.
Fungi spreading from athlete’s foot (known as ‘dermatophyte fungi’) cause most fungal nail infections. Far less often a nail infection is due to other types of fungi, usually yeasts (eg. Candida) and moulds (e.g. Scopulariopsis), which do not cause athlete’s foot. These like to attack nails that are already weak, perhaps after an old injury. Fungal infections of toenails are common, those of fingernails far less so. Both are seen most often in the elderly.
No, but several family members may have them at the same time because they can catch them from each other.
At the start, there are usually no symptoms. Later the nails may become so thick that they hurt when they press on the inside of a shoe. They are then hard to trim. The look of an infected nail, particularly a fingernail, can be embarrassing.
When fungi invade a nail, they usually start at its free edge, and then spread down the side of the nail towards its base. Eventually the whole nail may be involved. The infected areas turn white or yellowish, and become thickened and crumbly. Less common patterns of infection include white patches or streaks on the nail surface. The nails most commonly affected by fungal infections are those on the big and little toes. When several fingernails are infected, they are usually on the same hand.
Many nail problems can look like a fungal infection – for example the changes seen in psoriasis, or after a bacterial infection or an old injury – however, long courses of antifungal tablets will not help them. This is why the diagnosis of a fungal infection may confirmed before treatment starts. Your doctor will take a piece from a crumbly area of your nail and send it to the laboratory to check if a fungus can be seen under the microscope or grown in culture. The right treatment may depend on knowing which fungus is causing the trouble but it can take several weeks for the final culture results to come through.
Yes – usually they can.
Fungal infections of the nail do not clear up by themselves, but not all of them need treatment. Many people with infected toenails are not bothered by them at all. In that case they can be left alone. On the other hand, if infected nails are embarrassing or uncomfortable then they are usually worth treating.
The aim of the treatment is to get rid of the fungus: the nail will then usually return to normal. However, if the nail was abnormal before it picked up the fungal infection, it will be hard to clear and may just go back to its former state. Nail infections caused by moulds and yeasts can be very resistant to treatment.
Treatments put on the nail do much less well than those taken by mouth. They work best if the infection is at an early stage, just on the free edge of one or two nails, or lying close to the surface of the nail. The preparations used most often are amorolfine nail lacquer and tioconazole nail solution. Alone, they may not be able to clear the deeper parts of an infected nail, though regular removal of abnormal nail material with clippers or filing can help with this. Used in combination with an antifungal remedy taken by mouth, they increase the chance of a cure. They may have to be used for a period of 4 to 12 months before a response is noted.
Three medicines are available for use in fungal nail infections:
Remember that the new normal nail will grow slowly outward from its base, and it may be 6 months to a year after the treatment has finished before the nails look normal again. Fingernail infections clear up more quickly and completely than toenail ones.
Sometimes very thick nails that are not likely to respond to tablets alone may have to be removed under a local anaesthetic.