A fungal nail infection is a fungus gets into your fingernail, toenail, or the skin under your nail, usually through a small cut.

The infected toenail usually turns white or yellow. Sometimes it’s painful.

Toenails that are exposed to moisture and warmth a lot are more likely to get infected by a fungus. This can happen from wearing sweaty shoes often and from walking barefoot on shower floors.

Toenail fungus usually doesn’t need treatment unless it’s causing pain. It often comes back after it has cleared up.