Fungal nail infections

Also called onychomycosis

Fungal infection of the toenails or fingernails can cause discolouration and thickening of 1 or more nails.

Key points about fungal nail infections

  1. Fungal nail infections are common and usually affect toenails more often than fingernails.
  2. Most mild fungal nail infections are not serious and can be left untreated. 
  3. Some people are at risk of complications from nail infections and must seek medical advice, for example people with diabetes, peripheral vascular disease or connective tissue disease.
  4. Treatment for fungal nail infections include antifungal nail paints that you apply to the nail or antifungal tablets or capsules.

What causes fungal nail infections?

  • A fungal nail infection occurs when a fungus infects a fingernail, toenail or the skin under the nail (called the nail bed). 
  • You are more likely to get a fungal nail infection if your nail has been damaged through small cuts in the skin around your nail or through the opening between your nail and nail bed. 
  • You can get a fungal nail infection from sharing personal items such as nail clippers, or towels, walking barefoot in public showers or pools, or if you have athletes foot (a fungal infection between the toes), where the fungus spreads from your skin to your nail.  
  • Smoking, having have certain other health conditions, such as diabetespsoriasis or peripheral arterial disease  and taking medication that weaken your immune system can increase your risk of getting a fungal nail infection. 

What are the symptoms of fungal nail infection?

A fungal nail infection may not cause any obvious symptoms at first but as the infection progresses you may notice the following symptoms:

  • Change in colour of some or all of your nail — turns yellow, white, blue, purple or black.
  • Thickening and change in shape of the nail, making them 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.
  • The skin near the nail may itch, or crack.
  • Separation of the nail from the nail bed. 

When to seek help 

Most mild fungal nail infections are not serious and can be left untreated. See your pharmacist or doctor for treatment if:

  • The nail/s are painful or they bother you.
  • You are at risk of complications (such as cellulitis) from the infection, eg, if you have diabetes, peripheral vascular disease or connective tissue disorders. 

Many nail conditions can look like a fungal infection such as an old injury, a bacterial infection or psoriasis. Your doctor may take a small sample of your nail to confirm if it really is a fungal infection.

How are fungal nail infections treated?

Fungal nail infections can be difficult to cure. Your doctor or pharmacist can talk to you about your treatment options. Treatment includes applying medication to the nail such as an antifungal paint or taking antifungal tablets or capsules. Points to consider are:

  • Treatment with antifungals tablets or capsules is only successful for about 70–80% of people, and the use of antifungal paints is less effective. 
  • Even after successful treatment of the fungal infection, the nail may not look completely normal.  
  • There is a 1 in 4 chance that the fungal infection will come back.
  • Treatment is often needed for several months. It can take up to 12 months to confirm successful treatment, due to the slow growth of the nail unit.
  • Treatment is much more likely to work with good hygiene practices.

Antifungal nail paints (also called nail lacquer)

  • These treatments are applied directly to the nail, such as amorolfine (Loceryl®) and ciclopirox (Bactrafen®). 
  • They are less effective than taking tablets or capsules and are especially not effective for nails that have thickened.
  • They may be used when the infection is in 1–2 nails or when taking antifungal tablet or capsules are not suitable.
  • Applying nail paints requires good mobility and eyesight and time to file and cleanse nails before applying them. They will need to be used for at least 612 months. 

Antifungal tablets or capsules

  • Taking antifungal tablets or capsules are the preferred treatment for nail infections, especially if the entire nail is infected or if the nail is thickened. Examples of oral medications are terbinafine and itraconazole
  • Antifungal medication is taken for 6 weeks for fungal infections of the fingernail and for 3 months for fungal infections of the toenail.
  • They are not suitable for people with certain conditions like liver disease or if you are pregnant and they interact with many other medicines which can increase your risk of side effects. Tell your doctor about all medicines and herbal products you are taking so they can check for interactions (how they could react with each other).

How to practise good foot hygiene

Whether you decide to have treatment or not, you should still practise good foot hygiene to stop the infection getting worse or spreading to others.  

  • Keep your nails clean and trimmed.
  • If your fingernails are affected, avoid repeated hand washing and use of detergents and other chemicals. Wear protective gloves. 
  • If your toenails are affected, good foot care is important – wash and dry your feet well, and check them regularly for cuts and rubs.
  • Treat any other fungal infections such as athletes foot.
  • Keep your feet cool and dry by wearing breathable footwear and cotton socks as fungal infections like warm and damp places.
  • Wear clean socks every day.
  • Avoid high heels and shoes with narrow, pointy toes that may injure your nails.
  • When using shared showers, eg, at the swimming pool, wear protective footwear. 
  • If you need help from a podiatrist (someone who specialises in feet care), your doctor will be able to refer you to one.

Learn more

The following links provide more information about fungal nail infections. Be aware that websites from other countries may have information that differs from Aotearoa NZ recommendations.

Fungal nail infections DermNet NZ
Fungal nail infections NHS Choices, UK


  1. Management of Fungal Nail Infections BPAC, NZ, 2009
  2. Fungal Nail Infections DermNet NZ
  3. Fungal Skin Infections DermNet NZ
  4. Antifungal preparations NZ Formulary
  5. Terbinafine Safe prescribing Nail it Safer RX 
Credits: Sandra Ponen, Pharmacist. Reviewed By: Maya Patel, MPharm PGDipClinPharm, Auckland Last reviewed: 07 Dec 2021