What Causes Fungal Nail Infections? Signs, Risk Factors and Treatment

Fungal nail infections — medically known as onychomycosis — affect around 1 in 10 people in the UK. Despite being so common, they're often misunderstood, frequently misdiagnosed, and many people wait much longer than necessary before seeking treatment.

In this article we'll explain exactly what causes fungal nail infections, who's most at risk, how to recognise one, and what effective treatment looks like.

What Is a Fungal Nail Infection?

A fungal nail infection is an infection of the nail — and sometimes the surrounding skin — caused by microscopic fungi. The most common type is caused by dermatophyte fungi (the same group responsible for athlete's foot), though moulds and yeasts can also cause nail infections.

The infection typically starts at the edge or tip of the nail and gradually spreads toward the nail root. If left untreated, it can affect the entire nail plate, cause permanent nail damage, and spread to other nails or to other people.

What Causes Fungal Nail Infections?

Fungal nail infections occur when fungi enter and colonise the nail. This can happen through:

Direct Contact with Infected Surfaces

Fungi that cause nail infections thrive in warm, damp environments. Communal areas like swimming pool surrounds, changing room floors, shared showers and gym facilities are common sources of exposure. Walking barefoot in these areas allows fungi to come into contact with the nail and surrounding skin.

Spread from Athlete's Foot

Athlete's foot (tinea pedis) is a fungal infection of the skin, particularly between the toes. If left untreated, the same fungus can migrate into the toenail, causing a nail infection. This is why treating athlete's foot promptly is important even if it seems minor.

Trauma to the Nail

A nail that has been knocked, repeatedly compressed by tight shoes, or damaged in sport creates a vulnerable entry point for fungi. Runners and athletes with regular toe-nail trauma have a higher rate of fungal nail infection as a result.

Age

Older nails grow more slowly, have reduced blood supply and are more likely to have accumulated small cracks and damage — all of which make them more susceptible to fungal colonisation. Fungal nail infections are significantly more common in people over 60.

Weakened Immune System

Conditions or medications that reduce immune function — including diabetes, HIV, long-term steroid use or chemotherapy — can make it harder for the body to fight off fungal infections. Regular foot health checks are particularly important for these groups.

Circulation Problems

Reduced blood flow to the feet, common in diabetes and peripheral arterial disease, means the immune system is less effective at the nail site. This both increases the risk of infection and makes it harder to clear.

Signs of a Fungal Nail Infection

The signs of a fungal nail infection typically develop gradually and may affect one or several nails:

•       Yellow, white, brown or greenish discolouration

•       Thickening of the nail — making it harder to cut

•       Brittleness, crumbling or ragged nail edges

•       The nail lifting away from the nail bed (onycholysis)

•       White powdery patches on or under the nail

•       A faint, unpleasant odour from the nail

•       Debris under the nail

Early signs are often easy to dismiss — a slight yellowing at the tip, a little extra thickness. But fungal infections do not clear without treatment, and they tend to worsen over time.

Can You Treat a Fungal Nail Infection at Home?

Mild to moderate fungal nail infections can sometimes be managed with over-the-counter antifungal nail lacquers such as amorolfine (Loceryl). However, these treatments need to be applied consistently for 6–12 months and have limited effectiveness once the infection has reached the nail root.

It's also important to ensure the diagnosis is correct before starting treatment. Nail discolouration can be caused by psoriasis, trauma or other conditions — applying antifungal treatment to a non-fungal problem is ineffective.

 At our clinic in Shifnal, we can assess your nails and confirm whether a fungal infection is present. Visit our fungal nail treatment page for more details on what professional assessment and treatment involves.

 Think you might have a fungal nail infection? Book an assessment at Finest Feet Footcare in Shifnal →

How Are Fungal Nail Infections Treated Professionally?

Professional treatment focuses on two things: reducing the infected nail material and applying effective antifungal treatment to the site of infection.

At Finest Feet Footcare, this may involve safe mechanical reduction of thickened nail tissue (making the nail thinner and easier to treat at home), professional application of antifungal agents, and a tailored home care plan to support ongoing treatment.

Early treatment gives the best results. A nail that's only partially infected has a shorter treatment window than one that's been infected for years.

How to Reduce Your Risk

•       Dry your feet and toes thoroughly after bathing — fungi love moisture

•       Wear flip-flops in communal showers, changing rooms and pool areas

•       Don't share towels, socks or nail clippers

•       Change socks daily and choose moisture-wicking materials

•       Treat athlete's foot promptly before it can spread to nails

•       Cut nails straight across and file any rough edges

•       Allow feet to breathe — avoid wearing tight, enclosed shoes all day every day

Frequently Asked Questions

Is fungal nail infection contagious?

Yes. The fungi that cause nail infections can spread to other nails on the same foot, to fingernails, to the skin (causing athlete's foot), and to other people through shared surfaces and footwear. Prompt treatment reduces this risk.

Can fungal nail infections go away without treatment?

Very rarely, and usually only in very mild cases. In the vast majority of cases, fungal nail infections persist and worsen without treatment. The sooner treatment begins, the quicker and more complete the recovery.

How long does fungal nail treatment take?

This depends on the severity of the infection and which nails are affected. Toenails grow slowly — around 1.5mm per month — so even a successful treatment takes time to show as a clear new nail grows through. Most treatment programmes last 6–12 months. Patience and consistency are key.

Does having diabetes mean I'm more at risk?

Yes. People with diabetes are more susceptible to fungal nail infections and should seek professional assessment rather than attempting self-treatment. Nail infections in diabetic patients carry a higher risk of complications, including secondary bacterial infection. Regular professional foot care is strongly recommended.

Book Fungal Nail Treatment in Shifnal

Fungal nail infections are one of the most common conditions we treat at Finest Feet Footcare in Shifnal. With the right approach and consistent treatment, most infections can be successfully cleared.

We welcome patients from Shifnal, Telford, Newport and across Shropshire. Don't put it off — the earlier treatment starts, the better the outcome.

‍‍ ‍💚  Book your appointment at Finest Feet Footcare in Shifnal →  — clear nails are achievable.

‍ ‍Disclaimer:This article is general information and not a substitute for a clinical assessment.

Phone: 01952 872526
Email:finestfeetfootcare@gmail.com

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