Athlete's foot is caused by a fungus that grows on or in the
top layer of skin. Fungi (plural of fungus) grow best in warm, wet places, such
as the area between the toes.
Most of the time, a doctor can tell that you have athlete's foot by looking
at your feet. He or she will also ask about your symptoms and any past fungal
infections you may have had. If your athlete's foot looks unusual, or if
treatment did not help you before, your doctor may take a skin or nail sample
to test for fungi.
Read more about athlete's foot.