Depending on the type of fungus, your nails may discolor, thicken and develop crumbling edges or cracks. Fungal infections usually affect your toenails more frequently than your fingernails and are more common among older adults. Your risk for a toenail fungal infection is greater if your feet perspire heavily, and if you wear socks and shoes that hinder ventilation and don't absorb perspiration. You also can contract this infection by walking barefoot in public places and as a complication of other infections. Fingernail fungal infections often result from overexposure to water and detergents.
Moisture caught under artificial nails also can encourage fungus growth.
Dry your feet thoroughly after bathing. Change your socks often and wear leather-soled shoes. Use an antifungal spray or powder on your feet and inside your shoes. Don't pick at or trim the skin around your nails. Avoid walking barefoot around public pools, showers and locker rooms.