In the UK the most common type of fungi to infect the nails are called dermatophytes. These organisms are present throughout the environment, and once they infect the nails they live off of keratin which is a key component of nails.

These fungi thrive in damp conditions and are more common in swimming pools, gyms, spas and public showers. If you wash your hands or feet frequently, then this can also damage the nails and allow the fungus to enter.

Tight fitting shoes, spending too much time in warm shoes and socks, nail biting, trauma to nails from activities such as running can also increase your susceptibility to infections.

Another common way to get the infection is spread from neighbouring Athlete's foot, which is a fungal infection of the skin between the toes.

Some medical conditions can also make it more likely that you will suffer from this problem. These include diabetes, psoriasis, poor circulation or a generally reduced immune system.