Medical information for patients

Fungal nail infections (Onychomycosis)

Fungus infection of the nails of your hands or feet is known as onychomycosis. Fungal nail infections come on slowly and become visible as the infected part of the nail grows out from the near end of the nail where the nail is formed. The infected nail is usually abnormal looking, often yellower or whiter than normal, thicker and more brittle or softer than usual.


Usually the only symptom is that the nails affected by fungal infection look unsightly. Occasionally people find the affected nails ache. Probably this is because the thickened and sometimes deformed nails are putting pressure on the underlying nail bed or the neighbouring toes. The abnormal toe nails are slightly more likely to allow bacterial infection into the underlying toe.


Onychomycosis or fungal nail infection is an infection of the nail caused by fungus. Fungal spores (the seeds or eggs of fungi) are everywhere, and whether you get infected is more a question of whether you are susceptible at the time rather than that the fungi are particularly infectious. Fungi tend to particularly affect us in warm, moist parts of our bodies.


The look of the toenail gives a major clue. It tends to be thickened, perhaps crumbly at the edge, and different in colour to normal nail, often yellow or brown, sometimes white. However, other conditions (such as psoriasis) can cause these sorts of changes in the nail, as can previous trauma or damage to the nail. Therefore ideally the doctor (or nurse or podiatrist) will take clippings from the affected nail and send them to the laboratory for examination.

At the laboratory they will be examined under a microscope to look for fungi, and then the lab will try to grow any fungi that may be there, even if not enough to be seen when first examined (this is called culturing). The lab is likely to send two reports, the first to confirm whether or not fungi have been detected straight away, and the second, a few weeks later, to confirm whether they have managed to grow (culture) fungi from the scrapings.


Fungal infection is slow to fully develop in a nail, and as new nail grows very slowly, it is slow to eradicate. There are treatments available that can be applied to the surface of the nails, for example tioconazole lotion and amorolfine nail lacquer (which does not need to be applied so frequently), but these tend not to be as effective as treatment taken by mouth, such as terbinafine or an older medication, griseofulvin. If you embark on any treatment you will need to continue for at least three months for a toe nail or six weeks for a finger nail. You need to continue until normal nail has grown from the base of the nail at least half way towards the tip of the toe.

The other factor to bear in mind, when deciding on what to do, is that this is a fairly non-serious and superficial problem, but that medications can have major side effects. One of those that was used, by mouth, to treat fungi and thrush in the early 1980s actually led to liver inflammation and death in a number of patients (and was removed from use immediately)! Having said that, however, we now have oral medication available that has stood the test of time and proven to be very safe.

In addition to these medical treatments there are various other treatments which people use, such as tea tree oil.

You should weigh up how you wish to approach your onychomycosis in consultation with your doctor.

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