Onychomycosis (nail fungus)

Onychomycosis is a fungal infection of the nails that occurs mainly on the toenails but also on the fingernails. It makes the nails brittle, discoloured and thickened and is often stubborn to treat.

Causes and risk factors

• infection with dermatophytes, yeasts or moulds
• warm, damp conditions (e.g. in shoes, swimming pools, saunas)
• injuries to the nail or nail bed
• weakened immune system (e.g. diabetes, circulatory disorders)
• sweaty feet or poorly ventilated footwear
• athlete’s foot that spreads to the nail

Symptoms

• thickening and discolouration of the nail (yellowish, brownish or whitish)
• brittleness and splitting
• separation of the nail from the nail bed
• unpleasant odour, possibly inflammation

Treatment

• topical: antifungal nail lacquers (e.g. amorolfine, ciclopirox), creams or solutions
• systemic: antifungal tablets for severe cases – over several weeks to months, prescribed by a doctor
• podiatric: professional thinning of the thickened nail, which helps active ingredients penetrate better

Prevention

• wash feet daily and dry thoroughly, especially between the toes
• breathable shoes and cotton socks
• disinfect shoes regularly
• always wear flip-flops in pools, saunas and gyms
• do not share nail scissors and files

More in our guide Nail fungus.