Changes in the appearance of a fingernail or toenail are easy to dismiss as a cosmetic concern. However, persistent discolouration, thickening or crumbling can sometimes indicate a fungal nail infection.
Fungal nail infections are common and tend to affect the toenails more frequently than the fingernails. Although they are usually not dangerous in otherwise healthy adults, they can persist for months without treatment and may gradually spread to a larger area of the nail or to other nails.
Effective management depends on recognising the infection early, using an appropriate antifungal treatment where necessary and reducing the conditions that allow fungi to thrive.
What is a fungal nail infection?
A fungal nail infection develops when fungi infect the nail itself or the tissue underneath it.
The medical term for fungal nail infection is onychomycosis. Several different fungi can cause the condition, although dermatophytes are responsible for many cases.
These organisms favour warm and moist environments, which helps explain why toenails are particularly susceptible. Feet can remain enclosed in shoes for many hours and may be exposed to moisture from perspiration, communal showers, swimming pools and changing rooms.
An infection can initially affect a small area near the edge of the nail before gradually spreading.
The affected nail may become:
- White, yellow or brown in colour
- Thicker than usual
- Brittle or crumbly
- Rough or distorted
- Difficult to cut
Some infections remain relatively mild and painless. More extensive infections can make the nail uncomfortable and may create pressure when wearing shoes.
Not every abnormal looking nail is caused by fungus. Injury, psoriasis and other nail disorders can produce similar changes, which is why persistent or unusual symptoms may require professional assessment.
Why fungal nail infections can be difficult to clear
One of the main difficulties with fungal nail infection is the structure of the nail.
Unlike a superficial skin infection, the fungus can become established within and beneath the hard nail plate. This can make the affected area more difficult for topical treatments to reach.
Nails also grow slowly.
Even when an antifungal medicine is working, the damaged section does not immediately return to its normal appearance. Instead, healthy nail needs to grow from the base while the infected portion gradually moves towards the end and is trimmed away.
This process is particularly slow in toenails. It can therefore take many months before the appearance of the nail returns to normal.
A lack of visible improvement within the first few weeks does not necessarily mean that treatment has failed. The earliest indication that an infection is responding may simply be an area of healthier looking nail appearing at the base.
Consistency with treatment is consequently important.
Athlete's foot can spread to the nails
Fungal nail infections and athlete's foot are closely connected.
Athlete's foot is a fungal infection of the skin that commonly develops between the toes. Symptoms can include itching, flaking, cracking or sore skin.
If it is left untreated, fungi present on the surrounding skin can spread to the toenails.
Treating athlete's foot promptly is therefore an important part of preventing fungal nail infection and reducing the risk of reinfection after nail treatment.
Good foot hygiene also matters. Feet should be washed regularly and dried thoroughly, particularly between the toes where moisture can remain trapped.
Clean socks should be worn each day and shoes should ideally allow sufficient ventilation rather than keeping the feet continuously hot and damp.
How mild fungal nail infections can be treated
Treatment depends partly on how much of the nail is affected and whether there are other health considerations.
For some mild fungal nail infections, a topical antifungal medicine can be applied directly to the affected nail.
One option is amorolfine, an antifungal medicine supplied as a medicated nail lacquer. Amorolfine works by disrupting fungal cell membranes, which inhibits fungal growth and helps clear the infection as healthy nail gradually grows through.
Treatment requires patience because nail growth is slow. Depending on the product and clinical circumstances, amorolfine is normally applied regularly over a prolonged period rather than as a short course.
Before application, the affected area of the nail may need to be filed and cleaned as directed in the patient information leaflet. Files used on infected nails should not subsequently be used on healthy nails because doing so could help spread the infection.
Treatment should then be continued according to the instructions until the affected nail has grown out and been replaced by healthy nail.
For fingernails, this may take around six months. Toenail treatment can commonly require nine to twelve months.
Amorolfine is not suitable for every fungal nail infection. More extensive infections, infections involving several nails or cases affecting people with certain underlying medical conditions may require assessment by a healthcare professional.
Preventing the infection from returning
Treating the nail is only one part of managing fungal infection. Reducing exposure to the conditions that allowed the infection to develop can help prevent recurrence.
Keeping the feet dry is particularly important.
Socks should be changed regularly and shoes should be given sufficient time to dry between uses. Shoes that cause excessive sweating may create an environment in which fungi can thrive.
In communal areas such as gym showers, changing rooms and swimming pool facilities, wearing suitable footwear can reduce direct contact with potentially contaminated surfaces.
Personal nail equipment should also remain personal. Nail clippers, scissors and files should not be shared with other people.
When trimming the nails, keeping them reasonably short can make them easier to manage. However, cutting aggressively around the surrounding skin should be avoided because small injuries can create additional problems.
Any athlete's foot should also be treated rather than ignored, particularly if fungal nail infection has occurred previously.
Avoid covering the problem without treating it
Because fungal nail infection changes the appearance of the nail, it can be tempting to conceal it and otherwise ignore the condition.
Cosmetic nail varnish may be compatible with some forms of amorolfine treatment when used according to the product instructions. However, artificial nails should generally be avoided while using amorolfine because they can interfere with appropriate nail management.
It is also important to recognise that cosmetic improvement is not the same as clearing the infection.
Filing, polishing or covering a discoloured nail can make it look temporarily different, but these measures do not remove the fungus responsible.
The infection is considered to have cleared when healthy nail grows through from the base.
When medical advice is needed
Some fungal nail infections require more than self treatment.
A GP or other healthcare professional should assess an infection that is severe, continues to spread or has not responded to appropriate pharmacy treatment.
People with diabetes should seek professional advice about fungal nail infections because foot problems can have greater consequences when diabetes affects circulation or sensation.
The same applies to people with a weakened immune system.
Where the diagnosis is uncertain, a sample of the nail may sometimes be tested to establish whether fungus is genuinely responsible.
For more significant infections, a doctor may consider oral antifungal medicine. These treatments act throughout the body rather than being applied directly to the nail and may require additional assessment because they are not suitable for everyone.
Unexplained pain, swelling around the nail or significant changes that do not resemble a typical fungal infection should also be assessed rather than treated repeatedly without a confirmed cause.
Healthy nails require patience
Fungal nail infection is usually manageable, but treatment can take considerably longer than many people expect.
The main reason is not necessarily that the fungus is unusually resistant. Nails simply grow slowly and the damaged portion has to grow out before the nail can look completely healthy again.
Starting treatment when the infection is relatively limited can make management more straightforward. Good foot hygiene, prompt treatment of athlete's foot and avoiding prolonged damp conditions can then help reduce the chance of the infection returning.
The most important measure of improvement is not an immediate change in the old damaged nail. It is the gradual appearance of healthy nail growing from the base.
With appropriate treatment and consistent nail care, that process can eventually replace the infected nail with healthy growth.
