Fungal nail infection

Last updated:

Reviewed by:

Dr Bryony Henderson

, Lead GP at Livi

Medically reviewed

Fungal nail infection (FNI) is a common infection that typically happens under the toenail or fingernail. Learn the symptoms and how it’s treated.

What is a fungal nail infection?

Fungal nail infection (FNI), also known as onychomycosis, is a common fungal infection. It’s most common on the toenails but can also affect the fingernails. Though it’s not serious, it can take a long time to treat. 

What are the symptoms of a fungal nail infection?

  • White or yellow streaks and discoloration at the edge of your nail – this tends to be an early symptom

  • Changes in colour that spread to the middle of your nail

  • Thickening of your nail

  • Flaky patches

  • Loosening of your nail

If the infection isn’t treated and becomes more severe, you may feel some swelling and pain as the infection starts to lift the nail off your toe or finger. Your nail may then break and fall off.

If your nail falls off, it can take up to a year for the new nail to grow back to its full size.

How common are fungal nail infections?

Fungal nail infections are more common in the older population.

The infection tends to be more common in men, swimmers and people with other health problems like diabetes, HIV infections and peripheral vascular disease.

What causes a fungal nail infection?

The infection can be caused by several microscopic beings, like:

  • Dermatophytes, like Trichophyton rubrum or Tinea unguium

  • Yeasts, like Candida albicans

  • Moulds, like Scopulariopsis brevicaulis

These fungi are contagious and can be found in carpets, public showers and near public swimming pools. The fungus can settle on little breaks in the nail and with the dampness and warmth inside your shoes, it can rapidly grow and damage the toenail. They can also grow after other skin infections, like tinea pedis or tinea manuum.

How are fungal nail infections diagnosed?

When you see a GP, they will:

  • Ask you a few questions about your symptoms and have a closer look at the nail

  • Take a sample of the nail and send it off to the laboratory, which will tell them what type of infection you have under the nail and what type of treatment is best

  • They may refer you to a foot specialist if more attention is needed, especially if you have diabetes or another health condition

How is a fungal nail infection treated?

If your nail is starting to bother you or is causing pain, you can try:

  • Antifungal nail lacquer– this can treat your infection, but can take up to 12 months and doesn’t always work

  • Tablets for nail fungal infections – these are effective for fungal infections but may have side effects 

  • Removal of the nail – in severe infections, a small procedure can be done to remove the nail under local anaesthetic.

A doctor can advise you on the best treatment for your fungal nail infection.

How to prevent fungal nail infections

It’s always best to try to prevent fungal nail infections so you don’t need treatment. You can do this by:

  • Keeping your feet clean and dry

  • Wearing clean socks every day

  • Wearing flip-flops if you’re using public showers or going to public swimming pools

  • Throwing out old shoes

  • Keeping a close eye on your feet and make sure you get help if you notice any changes, like symptoms of Athlete’s foot

  • Not sharing towels, shoes or nail clippers

When should I speak to a doctor?

Make sure you see a GP if your infection:

  • Is getting worse and treatment has not worked

  • The nail is deformed and really damaged

  • Has spread to other nails

Last updated:
Reviewed by:
Dr Bryony Henderson, Lead GP at Livi