There are many different species of fungi and yeasts that cause nail infections. Some only infect nails, but others spread from skin to nails or vice versa. Dermatophytes are the most common (around 90%) fungal cause. They all feed off the protein ‘keratin’ that is found in nails and skin and are contagious, especially in those with damaged nails already. They hang around in warm, moist, dark places like inside shoes and around changing rooms and swimming pools. Prevention is better than cure for fungal nails require treatment with antifungals, Treatments can be topical (as for athlete’s foot) but oral medication is more effective (terbinafine, Itraconazole, fluconazole) but requires a prescription and careful monitoring of treatment.