Nail fungus is medically called onychomycosis. This is a chronic condition of the nails that affects the toenails more than the fingernails. This type of nail infection is often caused by a group of fungi known as dermatophytes. Nail infections may also be caused by molds and yeast. This leads to the gradual destruction of the nail plate. Nail fungus infection is quite common. It affects almost half of the population of 70-year-olds. It is also responsible for 50 percent of all nail diseases.
Infected nails more often are characterized by white, yellow, green, or brown patches or streaks. The nail may also become thicker, ragged, dull, or crumbly when touched. It may also separate from the nail bed and may be painful at times. In some cases, the infected nail also becomes smelly.