Fungal nail infection (onychomycosis)
Onychomycosis is a fungal infection of the nail. It is very common, especially in toenails, and its distinguishing practical feature is the patience it…
On this page
Medicines commonly prescribed for Fungal nail infection (onychomycosis)
For informational purposes only. Always consult a doctor before using any medicine.
Dosage form: CAPSULE, 100 mgActive substance: itraconazoleManufacturer: Esteve Pharmaceuticals S.A.Prescription requiredDosage form: CAPSULE, 100 mgActive substance: itraconazoleManufacturer: Viatris Pharmaceuticals S.L.U.Prescription requiredDosage form: CREAM, 10 mg/gActive substance: terbinafineManufacturer: Towa Pharmaceutical S.A.Prescription required
Onychomycosis is a fungal infection of the nail. It is very common, especially in toenails, and its distinguishing practical feature is the patience it demands: the nail grows slowly and treatment is measured in months, not weeks. People who abandon it halfway end up back where they started, and that is the most common reason for "it never clears".
How it presents
- the nail changes colour: yellowish, whitish, brown or blotchy;
- it thickens and becomes hard to cut;
- it crumbles at the free edge;
- it lifts away from the nail bed, leaving a gap underneath;
- whitish crumbly material builds up beneath it;
- it can become deformed and painful in shoes;
- sometimes there is an unpleasant smell;
- it almost always starts at the free edge and advances towards the root;
- in most cases there is athlete's foot on the skin as well.
What makes it more likely
- untreated athlete's foot — the commonest origin;
- older age, because the nail grows more slowly;
- diabetes, circulatory problems, reduced immunity;
- repeated nail trauma: sport, tight footwear;
- prolonged moisture: closed footwear, sweating, working with water;
- shared damp floors: pools, changing rooms, saunas;
- nail psoriasis, which is also confused with fungal infection;
- manicure and pedicure with unsterilised instruments;
- gel nails and long-worn semi-permanent polish.
Why it should be confirmed before treating
This is the key point of the article. Only about half of nails that look "fungal" actually have a fungus. The rest are psoriasis, repeated trauma, lichen planus, circulatory changes or age-related change. Since oral treatment lasts months and requires blood monitoring, it is not started blind: a nail sample is taken for microscopy and culture, or for PCR.
There is also one situation that cannot wait: a dark longitudinal band in a nail, or a colour change in a single nail with no history of injury, must be assessed to exclude nail melanoma.
When to see a doctor
- a nail has changed colour, thickness or shape;
- it hurts when walking or in shoes;
- you have diabetes, neuropathy or circulatory problems — always seek advice rather than self-treating;
- the surrounding skin is red, swollen, hot or discharging;
- there is a dark band in the nail or a mark that is enlarging;
- several nails are affected;
- over-the-counter treatments have not worked in three months;
- there are lesions on the elbows, knees or scalp — this may be psoriasis.
Treatment
- antifungal lacquers and solutions — amorolfine, ciclopirox: useful where less than half the nail is affected and the root is spared. Applied for 6–12 months;
- oral antifungals — terbinafine, itraconazole: far more effective for extensive involvement. Three to four months for toenails, six to twelve weeks for fingernails. They require liver function monitoring and a check for interactions with other medicines;
- filing or reducing the nail — thins it and helps the product penetrate;
- chemical or surgical nail removal in selected cases;
- laser — results are inferior to oral treatment and the evidence is limited;
- treat athlete's foot at the same time: without this, reinfection is only a matter of time.
About timescales: a toenail takes 9–12 months to grow out completely. Even if the fungus is dead by the second month of treatment, the damaged part of the nail will still be there until it has grown out entirely. An ugly nail does not mean the treatment has failed.
How to prevent recurrence
- dry your feet thoroughly, particularly between the toes;
- breathable socks changed daily;
- alternate footwear and let each pair dry for 24 hours;
- disinfect footwear with antifungal powder or spray during and after treatment;
- flip-flops in showers and changing rooms;
- cut nails straight across with your own instruments;
- do not share clippers or files, and ensure salon equipment is sterilised;
- treat any skin fungal infection as soon as it appears;
- take breaks between semi-permanent manicures;
- if you have diabetes, check your feet daily.
Common questions
Is it contagious? Yes, via shared damp floors, towels and manicure equipment, and also within the same household.
Can I paint the nail? During treatment it is better not to: polish hides the progress, and medicated lacquers do not work underneath it.
Do vinegar or tea tree oil work? They do not eradicate the infection. At best they improve the appearance slightly.
Are the tablets dangerous? Terbinafine has been in use for decades; blood monitoring and an interaction check make it safe for most people.
Can I leave it untreated? If it does not bother you, that is a reasonable option to discuss. But the infection advances, spreads to other nails and, in people with diabetes, can lead to complications.
Online consultation
In an online consultation the doctor reviews photographs of the nails, explains why it is worth confirming the fungus with a sample before months of treatment, reviews your medicines for interactions, chooses between lacquer and oral treatment, and sets out realistic timescales for improvement.
This material is for information only and does not replace a medical consultation.
Medically reviewed by
Reviewed on Jul 23, 2026
Online doctors for Fungal nail infection (onychomycosis)
Discuss your symptoms and possible next steps for Fungal nail infection (onychomycosis) with a doctor online.








