Fungal nail infections are more common in kids than most people think. These infections usually start with an athlete's foot rash around the toes that gets into the nails. The nails become thickened and discolored. Doctors can often tell by simply examining the nails, but sometimes sending a little sample for testing is necessary.

This fungus grows in a warm, moist, dark environment, which is why the inside of shoes is such a great place. Wearing white cotton socks and cool shoes or sandals can help to slow the spread of fungus. You can try some of the over-the-counter athlete's foot preparations, though Lamasil cream is probably the strongest. When the fungus gets into the nail, oral medications are usually needed. The best ones are Lamasil, Sporanox, or Diflucan. There are older medicines available, but they have more side effects.