Many people develop a fungal nail infection at some point in their life. It's not usually serious, but can be unpleasant and difficult to treat.
The infection develops slowly and causes the nail to become discoloured, thickened and distorted.
Toenails are more frequently affected than the fingernails.
The medical name for a fungal nail infection is onychomycosis.
This page covers:
Symptoms of a fungal nail infection
A fungal nail infection may not cause any obvious symptoms at first.
As it progresses, the infection can cause:
- discolouration of the nail – it may turn white, black, yellow or green
- thickening and distortion of the nail – it may become an unusual shape or texture and be difficult to trim
- pain or discomfort – particularly when using or placing pressure on the affected toe or finger
- brittle or crumbly nails – pieces may break off and come away completely
Sometimes the skin nearby may also become infected and be itchy and cracked or red and swollen.
Causes of fungal nail infections
Most fungal nail infections occur as a result of the fungi that cause athlete's foot infecting the nails.
These fungi often live harmlessly on your skin, but they can sometimes multiply and lead to infections. The fungi prefer warm, dark and moist places like the feet.
You're more likely to get a fungal nail infection if you:
- don't keep your feet clean and dry
- wear shoes that cause your feet to get hot and sweaty
- walk around barefoot in places where fungal infections can spread easily, such as communal showers, locker rooms and gyms
- have damaged your nails
- have a weakened immune system
- have certain other health conditions, such as diabetes, psoriasis or peripheral arterial disease
Fungal nail infections can be spread to other people, so you should take steps to avoid this (see below) if you have an infection.
Treatments for fungal nail infections
Treatment isn't always needed for a mild fungal nail infection because it's unlikely to cause any further problems and you may feel it's not worth treating.
Whether you decide to have treatment or not, you should still practise good foot hygiene (see below) to stop the infection getting worse or spreading to others.
Speak to your GP or pharmacist if you're bothered by the appearance of the affected nail, or it's causing problems such as pain and discomfort. They'll probably recommend:
- antifungal tablets – tablets taken once or twice a day for several months
- antifungal nail paints – special paints applied directly to the nail over several months
- nail softening kits – where a paste is used to soften infected parts of the nail, before they're removed with a scraping device
A procedure to remove the nail completely may be recommended in severe cases. Laser treatment, where a high-energy laser is used to destroy the fungus, is also an option. But this is only available privately and can be expensive.
Read more about treating a fungal nail infection.
Preventing fungal nail infections
You can reduce your risk of developing a fungal nail infection by:
- keeping your hands and feet clean and dry
- wearing well-fitting shoes made of natural materials and clean cotton socks – these will allow your feet to "breathe"
- clipping your nails to keep them short – don't share clippers or scissors with other people
- not sharing towels and socks with other people, and ensure your towels are washed regularly
- not walking around barefoot in public pools, showers, and locker rooms – special shower shoes are available to protect your feet
- replacing old footwear that could be contaminated with fungi
- treating athlete's foot as soon as possible to avoid the infection spreading to your nails
Nail salon equipment can sometimes be the source of fungal nail infections. If you regularly visit a salon, make sure any equipment used is properly sterilised between uses.