An antifungal is a medicine or substance that fights fungal infections. Fungi are living organisms like molds, yeasts, and mushrooms. While many fungi are harmless or even helpful (like the yeast that makes bread rise), some can cause infections on your skin, nails, or inside your body.

When you get athlete's foot, that itchy rash between your toes is caused by a fungus. An antifungal cream kills the fungus and clears up the infection. Ringworm (which isn't actually a worm at all, but a fungal infection) also requires antifungal treatment. Some people need antifungal medication for nail infections that make their toenails thick and discolored.

Doctors prescribe antifungals as creams, pills, or liquids depending on where the infection is and how serious it is. Just like antibiotics fight bacteria, antifungals fight fungi. You can find mild antifungal creams at the pharmacy for common problems like athlete's foot, but some infections need a doctor's prescription.