Please note: This information was current at the time of publication but now may be out of date. This handout provides a general overview and may not apply to everyone. 

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Am Fam Physician. 2004;70(5):928

What is onychomycosis?

A fingernail or toenail infection that is caused by a fungus is called onychomycosis (say: “on-ee-ko-my-ko-sis”). Toenails are more likely than fingernails to become infected. This infection can make your nails thick and discolored.

A warm, wet place is a good place for a fungus to grow. If you often wear heavy work boots that make your feet warm and sweaty, a fungus can grow around your toenails. If you often walk barefoot in locker rooms, you can pick up a fungus from the warm, wet floors.

People whose hands are often wet (for example, dishwashers in restaurants and professional house cleaners) are more likely to get fungal fingernail infections.

How do I find out if I have a fungal nail infection?

See your doctor if you think you have a fungal infection in your fingernails or toenails. Your doctor might cut a little piece of your nail and send it to a lab. This test can tell if you have a fungal infection or another kind of infection.

How is a fungal nail infection treated?

Several medicines can treat fungal nail infections. Some of these medicines are not safe in people with liver or kidney problems or congestive heart failure. Be sure to let your doctor know if you have one of these conditions.

What can I do to take care of my nails?

  • Keep your nails cut short and file down any thick areas.

  • Do not use the same nail trimmer or file on healthy nails and infected nails. If you have your nails professionally manicured, bring your own nail files and trimmers from home.

  • Wear waterproof gloves when you are working with water (such as washing dishes or floors). Wear 100 percent cotton gloves for dry work.

  • Wear 100 percent cotton socks. Change your socks when they are damp from sweat or if your feet get wet. Put on clean, dry socks every day. You can put over-the-counter antifungal foot powder inside your socks to help keep your feet dry.

  • Do not walk barefoot in public areas, such as locker rooms.

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