CausesBy Mayo Clinic staff
Swimmer's ear is an infection that's usually caused by bacteria commonly found in water and soil. Infections caused by a fungus or a virus are less common.
Your ear's natural defenses
Your outer ear canals have natural defenses that help keep them clean and prevent infection. Protective features include:
- Glands that secrete a waxy substance (cerumen). These secretions form a thin, water-repellant film on the skin inside your ear. Cerumen is also slightly acidic, which helps further discourage bacterial growth. In addition, cerumen collects dirt, dead skin cells and other debris and helps move these particles out of your ear. The waxy clump that results is the familiar earwax you find at the opening of your ear canal.
- Downward slope of your ear canal. Your ear canal slopes down slightly from your middle ear to your outer ear, helping water drain out.
How the infection occurs
If you have swimmer's ear, your natural defenses have been overwhelmed. Conditions that can weaken your ear's defenses and promote bacterial growth include:
- Excess moisture in your ear. Heavy perspiration, prolonged humid weather or water that remains in your ear after swimming can create a favorable environment for bacteria.
- Scratches or abrasions in your ear canal. Cleaning your ear with a cotton swab or hairpin, scratching inside your ear with a finger, or wearing headphones or hearing aids can cause small breaks in the skin that allow bacteria to grow.
- Sensitivity reactions. Hair products or jewelry can cause allergies and skin conditions that promote infection.
- Goguen LA. External otitis. http://www.uptodate.com/home/index.html. Accessed Aug. 4, 2010.
- Osguthorpe JD, et al. Otitis externa: Review and clinical update. American Family Physician. 2006;74:1510.
- Kaushik V, et al. Interventions for acute otitis externa. Cochrane Database of Systematic Reviews. 2010:CD004740.
- Swimmer's ear: Otitis externa. Centers for Disease Control and Prevention. http://www.cdc.gov/healthywater/swimming/rwi/illnesses/swimmers-ear.html. Accessed Aug. 4, 2010.
- Swimmer's ear. American Academy of Otolaryngology — Head and Neck Surgery. http://www.entnet.org/HealthInformation/swimmersEar.cfm. Accessed Aug. 18, 2010.
- Rubin MA, et al. Pharyngitis, sinusitis, otitis and other respiratory tract infections. In: Fauci AS, et al. Harrison's Principles of Internal Medicine, 17th ed. New York, N.Y.: The McGraw-Hill Companies Inc.; 2008. http://www.accessmedicine.com/content.aspx?aID=2883486. Accessed Aug. 18, 2010.