Typically, fungal foot infection first appears as athlete’s foot – experienced as itching and maceration of skin between the toes – and later as fungal nail infection (onychomycosis). Treatment with antifungal agents can eliminate athlete’s foot but it often returns. The reservoir for infection is usually on the soles of the feet. Very dry skin on the soles with white chalky lines is indicative of chronic fungal infection.

Dermatophyte infection of the feet is often transferred to the groin where it causes a fungal infection commonly known as jock itch. Particles of skin debris are thought to be carried to the site when underpants are put on.

Fungal foot infection is an important risk factor for cellulitis – a bacterial infection – of the legs because the broken skin between the toes provides a portal for infection. 

Treatment options

Fungal foot infection can be treated effectively using an azole for four weeks or a terbinafine for one week. Azoles are fungistatic but terbinafine is fungicidal for dermatophytes. When treatment is started the itching and inflammation subside in a few days but treatment should be continued for one to two weeks after this to ensure the infection is completely eradicated. The most common problem in the management of athlete’s foot is poor adherence to treatment.

Antifungal cream, gel or spray should be applied to both feet, between and over the toes, the soles and the sides of the feet. A single-dose treatment (Lamisil Once) is also available, which needs to be left in place for 24 hours where it forms an invisible, water-resistant film on the skin that acts as a drug reservoir. High levels of terbinafine persist in the stratum corneum for 13 days. Overall, this treatment is as effective as a one-week treatment with terbinafine cream. The evidence for effectiveness of products based on undecylenic acid is weak. 

Fungal foot infection almost always returns, often as a result of reinfection from contaminated shoes or clothing. Throwing away old socks and shoes and spraying shoes with terbinafine can reduce the risk of reinfection.

In order to minimise the risk of fungal foot infection people should be advised to dry between their toes after washing, not share towels and try to avoid occlusive footwear. Keeping fungal foot infection at bay with regular prophylactic antifungal treatment (e.g. terbinafine) could help to prevent the development of fungal nail infection.