Fungal Nail Infection (Onychomycosis)

What is a fungal infection of a nail?

Fingernails and toenails can get infected with fungus. Medical terms for the infection are onychomycosis or tinea unguium.

What is the cause?

Fungus grows best on warm, damp skin. The fungus that infects the nail usually spreads from infected skin close to the nail.

Nail infections are more common and may be harder to treat in people who have diabetes or poor circulation, and in people whose immune systems are weakened by HIV, cancer, or other health problems.

What are the symptoms?

Symptoms may include:

  • Thickened, yellow or brown nails
  • Brittle nails that may crumble, flake, or lift off the finger or toe

How is it diagnosed?

Your healthcare provider will ask about your symptoms and medical history and examine you. Most often it is diagnosed by looking at the nail, but the infection can also be confirmed with lab tests. A sample of the nail may be tested in the lab for fungus.

How is it treated?

If the infection is very mild, your provider may prescribe medicine you can put on the nail. For more severe infections, your provider may prescribe an antifungal medicine to be taken by mouth.

You may need to take the medicine until the nail grows all the way out and there is no longer any sign of the fungal infection. This usually takes about 6 months for fingernails and 12 months for toenails.

How can I take care of myself?

Follow the full course of treatment prescribed by your healthcare provider. Ask your healthcare provider:

  • How long it will take to recover
  • If there are activities you should avoid and when you can return to your normal activities
  • How to take care of yourself at home
  • What symptoms or problems you should watch for and what to do if you have them

Make sure you know when you should come back for a checkup.

How can I help prevent a fungal nail infection?

Fungus grows best on warm, damp skin. To help prevent fungal infections, it’s important to keep your hands and feet as dry as possible. It may help to:

  • Avoid biting your nails.
  • Wear gloves if your work or daily activities put your hands at risk for getting scratched, poked, or irritated. Also, it may help to wear gloves if your hands are in water much of the day. Take the gloves off several times a day to make sure they are dry.
  • If you have nail infections often, get checked for diabetes.
  • Wear cotton or athletic socks that wick moisture away from your feet.
  • Change your socks every day, or more often if the socks become damp.
  • Wear sandals or shoes that let your feet breathe. This means avoiding rubber or plastic shoes unless they have openings. Canvas or leather shoes are usually a better choice
  • Air out your shoes when you aren’t wearing them. It is helpful to have more than 1 pair of everyday shoes and to switch shoes every day.
  • Wear something such as flip-flop sandals when you take a shower in a locker room or other shared shower stall.
  • Disinfect shower and locker room floors.
Developed by RelayHealth.
Adult Advisor 2015.1 published by RelayHealth.
Last modified: 2014-07-28
Last reviewed: 2014-07-10
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright ©1986-2015 McKesson Corporation and/or one of its subsidiaries. All rights reserved.

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