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Onychomycosis (Fungal Nail Infection)

Onychomycosis is an increasingly common disorder, accounting for 20% of all nail diseases. It occurs almost exclusively in adults and one in two people over the age of 70 suffers from it. The risk therefore increases with age and through underlying nail disease. 

Disease overview

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Onychomycosis is an infection of the nails caused by a fungus and is commonly referred to as fungal nail infection. Symptoms of the infection will vary depending on the type of fungus involved, but thickened nails and yellow discoloration (as pictured above) are common.

Approximately one half of all nail conditions are the result of fungus, making onychomycosis the most common nail disorder. A large survey estimated that as many as 16% of Europeans may have fungal nail infections. Onychomycosis can affect both the fingernails and toenails; however the toenails are more likely to be involved. The reasons for this are not entirely clear, but the slower growth of toenails, prior fungal infection of the feet (such as athlete’s foot) may make it easier for fungi to establish themselves and cause an infection of toenails. As well, fungi typically thrive in warm, moist conditions. Closed and plastic shoes are therefore ideal environments for these organisms, making it easier for them to infect the feet and toenails. Walking barefoot in locker rooms also increases the risk of infection, as this hot and humid environment is susceptible to fungal contamination. Fingernails can also be infected, often by another type of fungus. Often these types of infections occur in people whose hands have been exposed to water for long periods of time, for example dishwashers in restaurants or professional house cleaners. Wearing double gloves – cotton on the inside and latex or vinyl on the outside – when in contact with water helps to prevent against developing these types of infections.


Your healthcare professional will likely start an examination by simply looking at your nails. Different types of onychomycosis have characteristic features that suggest fungal nail infection, and these can be used to differentiate onychomycosis from other types of infection. There are additional laboratory tests that are used to confirm the diagnosis. Looking at sections of nail under a microscope can sometimes be used to directly visualise the fungi that cause the disease. As well, if fungi can be grown in the laboratory from samples and scrapings of nail, this is evidence that fungi are responsible for the disease. Often a healthcare professional will make a preliminary diagnosis based on examining the nails and confirm this in the laboratory using microscopy and culture techniques. It might be a few weeks before your healthcare professional gets the results of the laboratory tests.



  • Onychomycosis is a type of nail infection caused by pathogenic fungi.
  • Approximately half of nail conditions are onychomycosis, making it the most common nail disorder.
  • Both fingernails and toenails can develop fungal infections, but toenails are more commonly affected.
  • Healthcare professionals use a combination of clinical examination and laboratory tests to successfully differentiate onychomycosis from other types of disease.

Causes, Triggers and Risk Factors

Not everyone has the same risk of developing fungal nail infections. Studies have shown that there are several factors that increase the risk of common onychomycosis infections:


The risk of developing onychomycosis increases with age. This may be because older people have slower growing nails, have difficulties taking care of their feet and toenails and are more likely to have other risk factors for the disease (poor peripheral blood circulation, diabetes, weakened immune state).

Poor peripheral blood circulation

People with poor peripheral blood circulation are more susceptible to fungal infections.


Diabetes has several effects on the circulatory system, and has been shown to increase the risk of developing onychomycosis.


Onychomycosis is more common in people who have psoriasis than those who do not.


Some sports may increase exposure to pathogenic fungi and therefore increase the risk of fungal infection. People who swim, for example, are more likely to have onychomycosis than those who do not.


As with other types of infection a weakened immune system increases the risk of developing onychomycosis.

Genetic factors

Some people seem to be naturally more susceptible than others to fungal infections such as onychomycosis. The exact genes involved have not been identified, but some research suggests that you are more likely to develop fungal nail infections if you have a family history of the disease.

Cases of fingernail onychomycosis have a slightly different set of risk factors, including:

  • Prolonged contact with water
  • Prolonged wear of plastic gloves
  • Frequent or prolonged manipulation of sweet products (e.g. sweets, pastry)
  • Excessive use of detergents
  • Smoking
  • Repeated microtrauma to nails (e.g. through gardening)
  • Exposed profession (hairdresser, manicurist, podologist)
  • Other sites of fungal infection (e.g transfer of infection from toenails)


Treatments & Practical Tips

Below you will find some information on treatments that are available for onychomycosis, as well as considerations and practical tips for patients affected by the disease.  Speak to your healthcare professional for who will be able to advise the appropriate treatment for you.

Onychomycosis can be treated by removing as much diseased nail as possible. There are several different treatments for fungal nail infections. The different types of treatment include:

  • Mechanical
  • Topical
  • Systemic

Treatment may include one of the above options or a combination, depending on the severity of onychomycosis.  Your healthcare professional will be able to advise you on the most suitable treatment for you.  Each of these treatments has advantages and disadvantages for treating onychomycosis, depending on the type and the severity of your disease.

Keep in mind that treatment for onychomycosis (fungal nail infections) typically takes a long time to have an effect. Topical treatments applied directly to infected nails are usually prescribed for several weeks to months. Systemic treatments may be prescribed even longer, often half a year to one year in total. Some people may be frustrated with the slow changes when starting therapy, but remember that this is normal for onychomycosis treatment, and that sticking with the prescribed treatment dramatically improves your chances of clearing the infection.

As described above, onychomycosis can be treated by removing as much diseased nail as possible. There are several different treatments for fungal nail infections. The different types of treatment include:

  • Mechanical
  • Topical
  • Systemic

Treatment may include one of the above options or a combination, depending on the severity of onychomycosis.  Your healthcare professional will be able to advise you on the most suitable treatment for you. The below table describes the different treatment options commonly available.

Treatment Type



Mechanical treatment typically involves filing and trimming of infected nails. However partial or even complete removal of the nail may also be used in more severe cases.

Topical Treatment

Topical treatment involves solutions of antifungal agents that are applied directly onto the nails with the aim to kill the fungus and stop it spreading to healthy parts of the nail.

Systemic Treatment

Systemic treatment refers to capsules or tablets that are swallowed. These treatments also contain antifungal agents, but these agents are absorbed by the body and travel through the blood to the nails, where they become more concentrated. 

Your healthcare professional will help you to decide which treatment is best for you. In addition, you may want to consider the following factors when selecting an onychomycosis (fungal nail) treatment that is fight for you:

  • First, the treatment should never be worse than the fungal nail infection itself.
  • Consider your lifestyle, available time and the cost to help you decide among the options.
  • The treatment may need to be used for prolonged periods of time or continuously in order to keep your onychomycosis under control and stop it from progressing or coming back.
  • Keep in mind: treatment adherence strongly influences treatment effectiveness (if you don’t use it, it won’t work!)

In addition to treatment, there are several lifestyle measures that can help with onychomycosis. Most of these involve ways to limit exposure to the pathogenic fungi that cause the disease. This may help prevent the disease from coming back.

Avoid bare feet when possible

Using sandals in public showers or slippers in hotel rooms rather than bare feet can help limit your exposure to pathogenic fungi and reduce our chances of developing onychomycosis.

Rest shoes

Fungi grow preferably in warm, moist environments, and shoes can fit both of these criteria. Resting shoes (using a different pair of shoes) periodically can help reduce the chances of fungi growing within your footwear, where they have easy access to toenails and may cause infections.  Shoes can also be decontaminated with antifungal treatments.


Put clean, dry socks on everyday.

  • Socks should be washed at 60°C.
  • Wearing 100 percent cotton socks helps keeping your feet dry
  • Socks can also be decontaminated with antifungal treatments

Straight Nail Trimming


Trimming nails straight across rather than rounding them can help prevent fungal infections such as onychomycosis.

  • Don’t use the same nail trimmer or file on healthy and infected nails.

Prompt Treatment of Athlete's Foot

Athlete’s foot, also called tinea pedis, is a fungal infection of the skin on one or both feet. It sometimes occurs with onychomycosis. Quickly treating athlete’s foot if and when it appears can help prevent the infection from spreading to toenails, and reduce the chances of developing onychomycosis.

Dry Feet

Drying feet and the space between toes can help prevent recurrence. 

New Shoes After Cure

Buying new shoes after curing onychomycosis symptoms will help to prevent repeat recurrences from contaminated shoes.

Protect Fingernails

In case of fingernail onychomycosis, regularly drying hands and wearing a double pair of gloves (cotton plus latex or vinyl) will help protect fingernails from infection.


British Association of Dermatology

galderma.co.uk is focused on educating the public and patients about skin conditions and the different types of treatments that are available to treat and manage these diseases. This site is not intended as a substitute for medical advice from your doctor, dermatologist, or other healthcare professional and may include discussions about therapies or treatment options that are not suitable for your individual needs. We encourage you to use the information contained in this site to educate yourself about your disease and allow better communication between you and your healthcare professional.  Always consult a dermatologist or a healthcare professional for more information about your condition and the appropriate treatment / product that is right for your individual needs.

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