A fungal nail infection occurs when a fungus attacks a fingernail, a toenail, or the skin under the nail, called the nail bed. Fungi (plural of fungus) can attack your nails through small cuts in the skin around your nail or through the opening between your nail and nail bed.
If you are healthy, a fungal nail infection probably won't cause serious problems. But it may look bad, hurt, or damage your nail or nail bed.
A fungal nail infection could lead to more serious problems if you have diabetes or a weak immune system. Talk to your doctor about the best way to treat a nail infection if you have one of these problems.
Yeasts, molds, and different kinds of fungi can cause fungal nail infections. Most are caused by the same type of fungus that causes athlete's foot.
Fungi grow best in warm, moist places, and they can spread from person to person. You can get a fungal nail infection from walking barefoot in public showers or pools or by sharing personal items, such as towels and nail clippers. If you have athlete's foot, the fungus can spread from your skin to your nails.
A nail with a fungal infection may:
- Turn yellow or white.
- Get thicker.
- Crumble and split, and it may separate from the skin.
When you have a fungal nail infection, it can be uncomfortable or even painful to wear shoes, walk, or stand for a long time. The fungus could also spread to other nails or your skin. Over time, the infection can cause permanent damage to your nail or nail bed.
Your doctor will diagnose a fungal nail infection by looking at the nail, asking about your symptoms and past health, and possibly doing tests to look for fungi.
Whether to treat a fungal nail infection is up to you. If it isn't treated, it won't go away. It might get worse.