Onychomycosis is a fungal infection of the nail unit, more common in toenails than in fingernails. This infection is caused by a variety of fungi such as dermatophytes, non-dermatophyte moulds and yeasts (mainly Candida species). Onychomycosis leads to discoloration and deformation of the nails. In patients with complicating factors, deformed nails can lead to surrounding tissue damage and may lead to a secondary bacterial infection.