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Causes
By Mayo Clinic staffNail fungal infections are typically caused by a fungus that belongs to a group of fungi called dermatophytes. But yeasts and molds also can be responsible for nail fungal infections.
What are fungi?
Fungi are microscopic organisms that don't need sunlight to survive. Some fungi have beneficial uses, while others cause illness and infection.
All of these microscopic organisms:
- Live in warm, moist environments, including swimming pools and showers
- Can invade your skin through tiny visible or invisible cuts or through a small separation between your nail and nail bed
- Cause problems only if your nails are continually exposed to warmth and moisture — conditions perfect for the growth and spread of fungi
Toenails vs. fingernails
Nail fungus occurs more in toenails than in fingernails.
- Toenails often are confined in a dark, warm, moist environment inside your shoes — where fungi can thrive.
- Diminished blood circulation to the toes as compared with the fingers makes it harder for your body's immune system to detect and eliminate the infection.
References
- Onychomycosis. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merck.com/mmpe/sec10/ch125/ch125c.html?qt=nail%20fungus&alt=sh. Accessed May 5, 2011.
- Goldstein AO, et al. Onychomycosis. http://www.uptodate.com/home/index.html. Accessed April 21, 2011.
- Nail problems. American Podiatric Medical Association. http://www.apma.org/MainMenu/Foot-Health/Foot-Health-Brochures-category/Learn-About-Your-Feet/Nail-Problems.aspx. Accessed May 5, 2011.
- Kelechi TJ, et al. Four Vs for foot care. Vaseline, vegetable shortening, vinegar and Vicks VapoRub. Advance for Nurse Practitioners. 2004;12:67.
- Derby R, et al. Novel treatment of onychomycosis using over-the-counter mentholated ointment: A clinical case series. Journal of the American Board of Family Medicine. 2011;24:69.
- Habif TP. Nail diseases. In: Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 5th ed. Edinburgh, U.K.; New York, N.Y.: Mosby Elsevier; 2010. http://www.mdconsult.com/books/about.do? about=true&eid=4-u1.0-B978-0-7234-3541-9..X0001-6--TOP&isbn=978-0-7234-3541-9&uniqId=230100505-57. Accessed April 21, 2011.
- Hay RJ, et al. Onychomycosis: A proposed revision of the clinical classification. Journal of the American Academy of Dermatology. 2011. In press. http://www.sciencedirect.com/science?_ob=ArticleListURL&_method=list&_ArticleListID=1761598027&_sort=r&_st=13&view=c&_acct=C000010878&_version=1&_urlVersion=0&_userid=130561&md5=e8df8bcde3b532684246542bf6609d1a&searchtype=a. Accessed May 5, 2011.
- Baran R. The nail in the elderly. Clinics in Dermatology. 2011;29:54.
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