Nail fungus

Nail fungus (medically onychomycosis) is a contagious fungal infection of the finger- or toenails that thickens, discolours and weakens the nail. Toenails are affected most often, usually caused by dermatophytes (thread fungi).

Nail fungus develops when fungi enter under or into the nail through tiny injuries and feed on the nail keratin. Typical signs are yellowish-white or brownish discolouration, a thickened, crumbly nail and separation from the nail bed. It often starts harmlessly at the nail edge and spreads slowly. Because fungi thrive in warmth and moisture, they flourish in shoes, public showers, swimming pools and saunas.

Treatment depends on the extent and location. For mild cases, antifungal nail lacquers or solutions from the pharmacy are often enough, applied consistently over weeks to months. For more severe or multiple infections, a GP or dermatologist may prescribe tablets. Podologists can professionally remove the affected nail material, which improves the effect of topical treatments.

You should act as soon as a nail becomes permanently discoloured, thickened or detaches — the earlier, the better the chances of recovery. Patience is key: a healthy nail grows back slowly, and treatment often takes many months.

Make sure of a correct diagnosis, as not every discolouration is fungus. With diabetes, circulatory problems or a weakened immune system, nail fungus belongs in professional hands. Common mistakes: stopping treatment too early, continuing to wear the same untreated shoes, or sharing nail scissors.

Example

After the marathon season, a runner from Zurich notices that his big toenail has turned yellowish and thick — probably due to the moist warmth in his running shoes and visits to the indoor pool. He has the nail professionally reduced by a podologist and then consistently applies an antifungal lacquer. He also disinfects his shoes and always wears flip-flops in the changing room.

Frequently asked

How long does nail fungus treatment take?

Because a nail grows back only slowly, successful treatment usually takes several months — for toenails often half a year or longer. It is important to keep going consistently until a fully healthy nail has grown back and not to stop too early.

Is nail fungus contagious?

Yes, nail fungus can be transmitted — to other nails, to the skin and to other people. It spreads mainly via moist, warm floors in swimming pools, showers and saunas, and through shared towels, shoes or nail scissors.

When should I see a doctor or podologist?

For extensive or recurring infections, pain, or when topical products show no effect after weeks, a professional assessment makes sense. With diabetes, circulatory problems or a weakened immune system you should always have nail fungus treated professionally.

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