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A fungal infection of the nail (onychomycosis) usually affects toenails, a few nails at a time. It’s less common in fingernails. It can also appear on the soles of the feet and between the toes.

One in ten Finnish adults has nail fungus. It’s very rare in children but becomes more common with age. Nail treatment results are poorer among the elderly than young people.

Nail fungus often begins at the top of the nail and spreads along the side of the nail towards the cuticle. It makes the nail thicker and looser and causes colour changes, finally damaging the nail entirely. A correct fungal culture technique and interpretation are important in deciding the appropriate treatment and to avoid treatments that would be ineffective.


  • Trim your nails once a week.
  • Dry the areas between toes carefully, as moist toes attract fungal infections.
  • Monitor the condition of your skin. Try putting lamb’s wool or linen cloth strips between your toes if there is skin maceration.
  • Wear protective footwear in wet communal areas.
  • Let your shoes breathe for a few weeks after treatment to get rid of any mycelium.
  • Change your socks every day and wash them at 60°C.
  • Wear breathable socks and avoid tight-fitting shoes. The toe of the shoe should be comfortably wide and high, and there should be about 0.5 to 1 cm space in front of the longest toe. Heels that are too high change the position of the foot and push the toes against the toe of the shoe. This results in toe damage and predisposes to nail fungus, as damaged nails attract the fungus.
  • Over-the-counter products seldom cure nail fungus.

When should you seek treatment?

Contact a healthcare professional to see if you need treatment if your nails are thick, brittle or fall off, the tip is worn, or there are colour changes.


  • Nail fungus very rarely heals on its own. Treatment is individual and depends on the severity of the symptoms. Nail fungus often requires oral medication.
  • Antifungal medication is effective only in about half of those taking it.
  • Topically applied amorolfine lacquer is only effective in nail fungus affecting the top of the nail, and in children. It should be used 1 to 2 times a week. As it’s not very effective alone, it’s used in conjunction with medication taken by mouth. In addition, the affected part of the nail must be cut off and the thick part filed down.
  • Terbinafine is the most effective antifungal medicine. Treatment lasts 3 to 4 months. Typical but rare adverse effects of terbinafine are taste disturbances and even loss of taste for 1 to 2 months. Drug-induced rash is also possible. If the medication includes itraconazole and fluconazole, drug interactions must be taken into account. Remember that antifungal medication must not be taken during pregnancy or breast-feeding.

Information sources: The Finnish Medical Society Duodecim: Terveysportti, Lääkärin tietokanta database

FSHS General Practitioner / 29 March 2022

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