Onychomycosis refers to the fungal infection of the toenails. It is not a life-threatening condition, but it still may cause physical and occupational limitations, pain, discomfort, and embarrassment. As the nails thicken, they press against the shoe, causing pressure and pain. About 10% of Americans (23 million people) and as many as 90% of elderly people suffer from toenail fungus.

Once the common fungi that infect toenails become entrenched in the nail plate, they have a tendency to spread to adjacent toes in many individuals. Thickened fungal nails also have a tendency to become painful and ingrown over time.

Treating the fungus can be difficult because the nails receive little blood circulation, and the nails take a long time to grow out. Previously treatment has included oral medication or lacquers which can be painted onto the nails. Risk factors for toenail fungus include participation in fitness activities, trauma, occlusive footwear, living in a warm climate, having diabetes, and a having family history of the condition.