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Causes
By Mayo Clinic staffYour ear canals have features that help keep them clean and prevent infection. Glands in the canal secrete a waxy substance (cerumen) that provides protection through several means:
- Cerumen creates a thin, water-repelling film on the skin of the ear canal.
- It's an acidic substance, which creates an unfriendly environment for bacterial growth.
- It contains some proteins that act as mild antibacterial agents.
- It collects dirt, dead skin cells and other debris and transports them out of the ear canal. This waxy clump is the familiar earwax you find at the opening of your ear canal.
Another protective feature of the ear canal is its shape. The canal slopes slightly downward from the middle ear to the outer ear. This helps water drain out of the ear.
A breakdown of defenses
If you have swimmer's ear, the defenses of the ear canal have been overrun. Bacteria have easier access to the skin of the inner ear if:
- Excess moisture in the ear — from a lot of swimming, trapped water or humid weather — has thinned out the cerumen and made it less acidic.
- There's a break or abrasion in the skin from scratching with a cotton swab, hairpin or other object in the ear.
- You have a rash caused by sensitivity to hair products or jewelry.
Swimmer's ear is most often an infection caused by bacteria that are common in the environment. Infections caused by fungi or viruses are less common.
- Osguthorpe JD, et al. Otitis externa: Review and clinical update. American Family Physician. 2006;74(9):1510-1516.
- Ruckenstein M. Infections of the external ear. In: Cummings C, et al., eds. Otolaryngology: Head & Neck Surgery. 4th ed. Philadelphia, Pa.: Elsevier/Mosely; 2005. http://www.mdconsult.com/das/book/body/102996601-2/0/1263/1195.html?tocnode=49546210&fromURL=1195.html#4-u1.0-B0-323-01985-4..X5001-1--part11_5058. Accessed Aug. 25, 2008.
- Grunstein E, et al. Diseases of the external ear. In: Lalwani A, ed. Current Diagnosis & Treatment in Otolaryngology - Head & Neck Surgery. 2nd ed. New York, N.Y.: McGraw Hill; 2008. http://www.accessmedicine.com/content.aspx?aid=2829939. Accessed Aug. 25, 2008.
- Goguen L. External otitis. http://www.uptodate.com/home/index.html. Accessed July 25, 2008.
