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Nail fungus: Who gets and causes

Who gets nail fungus?

Nail fungus is common, and anyone can get it. However, some people have a higher risk of developing a fungal nail infection. Your age, health, and even your lifestyle can increase your risk.

Age. The risk of developing a fungal nail infection increases with age. It’s most common in old age and least common in children.

Before the age of 6, it’s rare to develop a fungal nail infection.

Climate. Living in a hot, humid climate increases the risk of developing a fungal nail infection.

Health. You have an increased risk of developing a fungal nail infection if you have one or more of the following:

  • Athlete’s foot (or another skin infection caused by fungus)

  • Cancer and are receiving chemotherapy

  • Diabetes

  • Had a nail infection

  • Injured a nail or recently had nail surgery

  • People in your family frequently get nail infections

  • Poor circulation

  • Psoriasis

  • Received an organ transplant

  • Weakened immune system due to a disease like human immunodeficiency syndrome (HIV)

Do you have frequent nail infections?

If you get frequent nail infections, you may have untreated athlete’s foot.

Lifestyle. Your risk of getting a fungal nail infection increases if you:

  • Have wet feet or hands frequently throughout the day

  • Smoke

  • Spend a lot of time in water

  • Walk barefoot in a hot, humid place like a pool, public shower, or locker room

  • Wear tight-fitting, closed-toe shoes, especially if you have sweaty feet

  • Wear plastic gloves for hours every day

What causes nail fungus?

Tiny, microscopic organisms called fungi (the plural of fungus) cause a fungal nail infection.

Many people pick up the fungi when they have skin-to-skin contact with someone who has a fungal infection such as athlete’s foot or ringworm on their hands.

Another common way to get a fungal nail infection is by walking barefoot in a warm, moist area such as a pool deck or locker room. These fungi thrive in warm, moist areas.

You can also get a fungal nail infection by sharing an infected nail clipper or towel.

But you don’t have to catch it from someone. You can get it if your nails are frequently moist or you often wear sweaty socks and shoes.

The fungi usually infect a nail by getting into a:

  • Small cut in the skin surrounding your nail

  • Crack in your nail

  • Separation between the nail and finger (or toe)

The area under a nail gives fungi a warm, moist place to grow. The infection can then spread to other nails and even your skin.

Gupta A and Brintnell W. “Onychomycosis: A complex disease?” Poster presented at: 69th Annual Meeting of the American Academy of Dermatology; 2011 Feb 4-8; New Orleans.

Gold LFS and Rosen T. “Onychomycosis: Diagnosis, treatment, and prevention strategies.” Dermatology News (A CME/CE certified supplement). March 2016:2-15.

Verma S and Heffernan MP. “Onychomycosis.” In: Wolff K, Goldsmith LA, et al. Fitzpatrick’s Dermatology in General Medicine (seventh edition). McGraw Hill Medical, New York, 2008: 1817-20.