Nail fungus, known medically as onychomycosis, is a common infection that affects toenails much more often than fingernails. It develops slowly and is seldom painful at first, so it is often ignored for years. It does not clear without treatment, and several other conditions look the same, which is why a proper diagnosis is the first step.
Common signs
- A white, yellow or brown patch that starts at the tip or side of the nail and spreads.
- Thickening of the nail.
- A crumbly, brittle or ragged edge.
- The nail lifting from the nail bed, with chalky debris underneath.
- A distorted shape.
- Sometimes a slight smell.
- In later stages, discomfort when wearing shoes.
One or several nails may be affected. The big toenail is the most usual place.
Who is more likely to get it
| Factor | Why |
|---|---|
| Older age | Slower nail growth, reduced circulation, years of exposure |
| Athlete's foot | The same fungi spread from skin to nail |
| Sweaty feet, tight or closed shoes | Warm, damp conditions |
| Walking barefoot in communal showers, pools and gyms | Contact with fungi |
| Nail injury | Gives fungi a way in |
| Diabetes, poor circulation, reduced immunity | Lower resistance, slower healing |
| Family members with nail fungus | Shared exposure and susceptibility |
Why diagnosis matters
Not every thick, discolored nail is fungal. Conditions that can look very similar include:
- Nail psoriasis.
- Damage from tight shoes or repeated injury.
- Changes of aging.
- Eczema, and other skin conditions.
- A bruise under the nail.
- Bacterial infection, which is often green.
- Rarely, a growth or skin cancer under the nail.
Studies suggest that a large share of abnormal-looking nails are not caused by fungus. Antifungal tablets are taken for months and can have side effects, so doctors usually confirm the infection first. A clipping or scraping of the nail is sent to a laboratory. The test is quick and not painful.
Treatment options
Treatment is chosen by a doctor, pharmacist or podiatrist, depending on how much of the nail is affected.
- Antifungal nail lacquers and solutions are painted on for many months. They suit mild infections that do not reach the base of the nail.
- Antifungal tablets are more effective for wider infections. They are taken for several weeks to months, and your doctor may arrange blood tests.
- Softening and removing the infected part of the nail, with a special cream or by a podiatrist, can help other treatments to work.
- Leaving it untreated is sometimes reasonable for a mild infection that causes no trouble, after discussion with a professional.
Home remedies such as vinegar soaks and tea tree oil are popular, but good evidence that they cure nail fungus is lacking.
What to expect
- Treatment kills the fungus, but the damaged nail has to grow out. A toenail takes 12 to 18 months.
- A clear band of healthy nail growing from the base is the first sign of success.
- The infection can return. Prevention continues after treatment.
Looking after an infected nail
- Keep nails short, and file down thick areas gently.
- Use separate clippers and files for infected nails, and clean them after use. See How to Clean and Store Nail Tools.
- Dry your feet thoroughly after washing.
- Wear clean socks every day, and breathable shoes.
- Treat athlete's foot promptly.
- Avoid nail polish and artificial nails on the affected nail, unless your clinician says otherwise.
- Do not share towels, socks, shoes or nail tools.
Prevention
- Wash and dry your feet daily, including between the toes.
- Wear sandals or flip-flops in communal showers and changing rooms.
- Change socks daily and rotate your shoes.
- Keep toenails trimmed straight across. See Toenail Care: Trimming and Hygiene Tips.
- Choose nail salons that sterilize their tools. See Nail Salon Hygiene: What to Check Before Your Appointment.
- Replace old shoes that may harbor fungi, or treat them with antifungal spray or powder.
Managing sweaty feet helps too. See Foot Odor: Hygiene and Shoe Care Tips.
When to see a doctor promptly
- You have diabetes, poor circulation or a weakened immune system. Nail and foot infections can lead to serious complications.
- The nail or surrounding skin is painful, red, swollen or oozing.
- The infection is spreading to other nails or to the skin.
- A dark streak or patch appears under a nail. See Nail Discoloration: Causes and When to Get Help.
- Over-the-counter treatment has not helped.
Related on ArniSun
- Nail Discoloration: Causes and When to Get Help
- Toenail Care: Trimming and Hygiene Tips
- Foot Odor: Hygiene and Shoe Care Tips
- Nail Salon Hygiene: What to Check Before Your Appointment
- How to Clean and Store Nail Tools
Sources and further reading
Frequently asked questions
Is nail fungus contagious?
Yes, it can spread to other nails, to the skin and to other people through shared surfaces, towels and tools, though it is not highly infectious.
Can nail fungus go away without treatment?
It rarely clears by itself and usually worsens slowly. A mild infection that causes no symptoms does not always have to be treated.
How long does it take to cure a fungal toenail?
Treatment lasts from several weeks to many months, and the nail may need 12 to 18 months to grow out clear.