A fungal nail infection affects the hard material (keratin) that makes up the nails.
Fungal nail infections can affect part or all of the nail, including the nail plate, nail bed and root of the nail.
The infection develops slowly and causes the nail to become discoloured, thickened and distorted. The toenails are more frequently affected than the fingernails.
Onychomycosis is the medical name for a fungal nail infection.
Signs and symptoms of a fungal nail infection
The most common sign of a fungal nail infection is the nail becoming thickened and discoloured. The nail can turn white, black, yellow or green.
You'll not usually feel any pain at first, but the nail can look ugly. In most cases, a fungal nail infection won't cause any further complications. However, it may cause pain and discomfort if the infection isn't treated, although this is rare.
What causes a fungal nail infection?
Most fungal nail infections are caused by dermatophyte fungi, which also cause athlete's foot.
Athlete's foot is a fungal skin infection that affects the skin between the toes. It can easily spread to the toenails.
Ocassionally, a nail infection can be caused by other types of fungi, such as Candida (a yeast that causes infections such as vaginal thrush).
Several factors increase the risk of a fungal nail infection developing. For example:
wearing shoes that cause your feet to get hot and sweaty
being in a humid environment
regular damage to the nail or skin
poor health or certain health conditions, such as diabetesor psoriasis
Treating a fungal nail infection
Treatment isn't always needed for mild fungal nail infections. Your GP may send a clipping of your nail for laboratory testing to discover the exact cause of the infection and rule out other conditions. They'll then discuss appropriate treatments with you.
Fungal nail infections can be treated and usually cured, but some treatments can take several months to work. Antifungal medicines include antifungal tablets and nail paint.
Antifungal tablets are usually effective, but they may cause side effects. You should discuss this with your GP before deciding which treatment to use.
Surgery to remove the nail may be recommended in very severe or painful cases. Laser treatment, where a high energy laser is used to destroy the fungus, is also an option. However, this is expensive and is only available privately.
During and after treatment it's important to look after your nails properly and practise good foot hygiene to stop the infection returning.
Media last reviewed: 13/03/20
Signs and symptoms of a fungal nail infection
The most common sign of a fungal nail infection is the nail becoming thickened and discoloured. The nail can turn white, black, yellow or green.A fungal nail infection is usually painless at first, and in most cases it won't cause any further complications. But if the infection isn't treated, it may cause pain and discomfort, although this is rare.If you have pain in the affected toenail, it can eventually make walking and wearing shoes difficult. You may have problems writing if your fingernails are affected.As the infection progresses you may experience other symptoms, such as the nail becoming brittle, with pieces of nail breaking off and coming away from the toe or finger completely.If left untreated, the skin around the nail can sometimes become inflamed and painful. White or yellow patches may also be visible on the nailbed, or you may have scaly skin next to the nail.
Causes of a fungal nail
The most common causes of fungal nail infections are a fungal skin infection or damage to the nail or skin.
A fungal infection in the toenail is often caused by a fungal skin infection such as athlete's foot. About a third of people with athlete's foot also develop a nail infection. Athlete's foot usually affects the skin between your toes, causing it to become red, flaky and itchy.
Fungi grow and thrive easily in warm, damp environments, so an infection is more likely to occur after wearing trainers for long periods or if you often have hot, sweaty feet.
Fingernail infections are most often caused by a yeast called candida, which causes infections such as vaginal thrush.
You're more likely to develop a fingernail infection if your job involves a lot of handwashing or your hands are in water for long periods of time. This is because the skin at the base of your nail can become damaged and is more likely to become infected.
Your risk of developing a fungal nail infection is also increased if you have certain health conditions or health issues, such as:
diabetes or psoriasis
a weakened immune system
poor general health
Other factors that can increase the risk of nail infections include:
using artificial (cosmetic) nails
constant nail biting
living in a warm and humid climate
Nail infections are more likely to occur with increasing age. Sometimes there's no obvious cause for an infection.
Treating a fungal nail infection
Treatment may not be necessary in mild cases of fungal nail infection.
But if you don't treat the infection, there's a chance it will spread to other nails.
Using simple self-care methods may be effective in some cases. For example, not wearing footwear that makes your feet hot, keeping your nails short and maintaining a high level of foot hygiene can help prevent fungal nail infections.
Medication may be recommended if your fungal nail infection is more severe. Antifungal medicines, such as tablets and nail paints, are the two main treatments.
Your GP and pharmacist will be able to advise you about whether you need treatment and, if so, recommend the type you need.
Your nail's appearance may not return to normal after the infection has cleared. However, a sample of your nail should be tested if it still looks infected.
Taking antifungal medication in the form of tablets means that the treatment reaches your nail through your bloodstream.
Terbinafine and itraconazole are the two medicines most commonly prescribed for fungal nail infections and they can be very effective.
However, you may have to take the tablets for several months to ensure that the infection has completely cleared up. If you stop taking the medication too early, the infection may return.
An advantage of using antifungal tablets is that they'll also clear up any associated fungal skin infections, such as athlete's foot, at the same time.
However, side effects of antifungal tablets can include:
loss of sense of taste
Antifungal nail paint
If you prefer not to take antifungal tablets, your GP may suggest you try antifungal nail paint instead.
Nail paint isn't considered to be as effective as tablets because it's painted onto the infected nail and has to work its way through to the infection. It can often be difficult to reach all of the infection.
A fingernail may need around six months of treatment, and a toenail may take up to 12 months.
Chemical nail removal
The abnormal infected nail plates can be removed using a paste containing 40% urea (a chemical that occurs naturally in the body which can also be manufactured). The paste is available over the counter from pharmacies.
You carefully apply the paste to the affected nails, which are covered and left overnight. You then wash the paste off in the morning and repeat the process each night after filing down the nail as instructed. It usually takes about two weeks to dissolve the nail plates.
Chemical nail removal is a painless treatment that gradually removes the abnormal nail plate and the fungus. It allows you to avoid taking tablets for several months and avoid surgery, which can be painful.
Once the nail plates have been dissolved, antifungal nail paint should be applied to the nails twice a week to prevent the nails being reinfected as the new nail forms.
Surgery and laser treatment
Surgery to remove the infected nail may be recommended if your infection is very severe or painful and other treatments have proved ineffective.
If your nail is surgically removed, a new nail should eventually grow back in its place. However, it could take a year or more for the nail to grow back completely.
Laser treatment is another possible option if you have a fungal nail infection that's particularly stubborn. The laser emits high doses of light energy, which are used to destroy the fungus.
Research shows that laser treatment is a safe and effective procedure, with some studies reporting a success rate of up to 90% at three months.
However, there's currently little evidence to show that laser treatment provides a long-term cure, as most studies only follow patients up for a period of three months.
To achieve these high success rates, you need to be treated every three months for up to a year. As laser treatment is only available privately, this could prove expensive.
Foot care during treatment
During your treatment, you should see a new healthy nail start to grow from the base of your nailbed. This is a sign that the treatment is working. The old infected nail should begin to grow out and can be clipped away over the course of a few months.
Speak to your GP if a new nail doesn't start to grow after two to three weeks of treatment. Keep using the treatment until your GP says you can stop. Stopping too early could result in the infection returning.
Foot care tips
There are some things you can do to help keep the infection at bay during and after treatment. These are listed below.
keep your feet cool and dry, and wear shoes and socks that allow your feet to breathe
wear clean cotton socks and avoid wearing trainers
treat athlete's foot with antifungal medicine as soon as possible to avoid the infection spreading to your nails
clip your nails to keep them short
use a separate pair of clippers or scissors to cut the infected nail to avoid spreading the infection to other nails
wear well-fitting shoes without high heels or narrow toes
maintain good foot hygiene
wear clean shower shoes when using a communal shower
consider seeking treatment from a podiatrist if thickened toenails cause discomfort when walking
consider replacing old footwear as it could be contaminated with fungal spores