What is a fungal nail?
A fungal nail (onychomycosis) is a nail infected with a fungus or a yeast, causing changes to the nail. Fungal nails are very common and can usually be treated well.
What does a fungal nail look like?
A fungal infection of the nail can present in various ways. Common features are partial lifting of the nail plate at the tip (distal onycholysis); horny build-up under the nail plate that pushes it upwards; and superficial white discolouration of the nail plate (superficial mycosis). In some cases the whole nail plate can eventually be lost.
How does fungal nail develop?
Most fungal nails are caused by the common skin fungus Trichophyton rubrum (about 70% of cases) and Trichophyton mentagrophytes (about 20%). The remaining 10% of causes include Candida species. It is thought that most fungal nails originate from a fungal skin infection that spreads to the nail plate. The great majority of fungal nails (about 98%) are found on the feet; fungal infections of the fingernails are rare.
Who gets it?
Older people are roughly 30 times more likely to develop a fungal nail than children. The reason is not entirely clear; the fact that children’s nails grow faster than adults’ nails may play a role. It is estimated that about 5% of the population has one or more fungal nails.
Is it worth treating a fungal nail?
In most cases fungal nails do not need to be treated, because medically they do little harm. In people with diabetes, generally reduced immunity or recurrent skin infections (erysipelas) of the leg, treating fungal nails can nevertheless be medically important.
How is a fungal nail treated?
Antifungal cream and lacquer. In a fungal infection the fungal threads grow through the whole thickness of the nail plate, so topical antifungal creams work insufficiently because the active ingredient does not penetrate the nail plate well enough. A special nail lacquer containing amorolfine has been developed that penetrates better to the fungus in the nail. For an optimal result, the nail must be prepared before each treatment, for example with a file.
Tablets. Fungal nails can also be treated with oral antifungal medicines: a choice between terbinafine tablets and itraconazole capsules. To combat the fungus effectively, a treatment of several months is often needed.
Laser. In recent years attempts have also been made to treat fungal infection with laser. The idea is that the laser heats the nail enough to kill the fungus. Although laser is already widely used and results from small studies are positive, more scientific research is really needed into how effective this treatment is.
When fungal nails cause purely cosmetic complaints, it is questionable whether prolonged treatment with oral medicines is justified. Although side effects of these antifungals are not very frequent, a good balance must always be found between the benefits and the risks. Most dermatologists will therefore only prescribe oral medicines for fungal nails at the patient’s explicit request.
What is the outlook?
When treatment has been carried out well, a healthy, fungus-free nail will emerge at the base of the nail. Since toenails grow at only about 1.5 mm per month, it can sometimes take a whole year before the infected part of the nail has grown out completely. Unfortunately, a new fungal infection can appear over time and the complaints can begin again.
When to see a doctor
See a doctor if a nail becomes thickened, discoloured or crumbly and it bothers you, or especially if you have diabetes, reduced immunity or recurrent leg infections, when treatment may be more important.