• Clinical science

Otitis externa (Swimmer's ear)


Otitis externa (OE) refers to inflammation of the external auditory canal, which is most often the result of a local bacterial infection. Risk factors for OE include injury to the skin of the external auditory canal and/or exposure to water. OE is characterized by ear pain, discharge, and tragal tenderness. Otoscopy may reveal a furuncle (localized OE) or a red, edematous external auditory canal (diffuse OE). OE is primarily a clinical diagnosis. Treatment involves keeping the external auditory canal dry and administering fluoroquinolone and hydrocortisone ear drops. Systemic antibiotic therapy is usually indicated in immunosuppressed and/or diabetic patients who are at risk of a more severe variant called malignant otitis externa (MOE). MOE, which is almost always caused by Pseudomonas aeruginosa, may present with facial nerve palsy and is potentially fatal because it spreads rapidly to the base of the skull. Immediate referral and treatment with systemic antipseudomonal antibiotics are indicated.



Clinical features


Subtypes and variants

Malignant otitis externa (necrotizing otitis externa)

Malignant otitis externa is a severe infection that is often lethal!



Fungal otitis externa should be suspected when symptoms do not resolve with local and/or systemic antibiotic therapy (especially among immunocompromised and diabetic patients)!





  • Indications
  • Interventions
    • Frequent swimmers should keep the auricle and external auditory canal clean and dry.
      • Use a tight-fitting bathing cap.
      • Use a hairdryer at the lowest heat setting and not too close to the ear.
      • Consider use of acetic acid and/or alcohol-based ear drops to dry the ear and to re-acidify the ear canal.
    • Treat underlying chronic dermatologic conditions.
    • Hearing aids should be removed and cleaned regularly.
    • Recommend that the patient avoids manipulation of the ear canal (e.g., use of cotton buds to clean the ear).


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  • 2. Fischer C. Master the Boards USMLE Step 2 CK. New York, NY: Kaplan Publishing; 2015.
  • 3. Chen SSP. Pseudomonas Infection. In: Pseudomonas Infection. New York, NY: WebMD. http://emedicine.medscape.com/article/970904-overview. Updated March 9, 2016. Accessed February 15, 2017.
  • 4. Grandis JR, Yu VL. Malignant (necrotizing) external otitis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/malignant-necrotizing-external-otitis. Last updated February 22, 2016. Accessed February 15, 2017.
  • 5. Dhingra PL, Dhingra S. Diseases of Ear, Nose and Throat. Elsevier; 2014.
  • 6. Nussenbaum B. Malignant Otitis Externa Follow-up. In: Malignant Otitis Externa Follow-up. New York, NY: WebMD. http://emedicine.medscape.com/article/845525-overview. Updated January 26, 2017. Accessed February 15, 2017.
  • 7. Handzel O, Halperin D. Necrotizing (malignant) external otitis. Am Fam Physician. 2003; 68(2): pp. 309–12. pmid: 12892351.
  • 8. Le T, Bhushan V, Chen V, King M. First Aid for the USMLE Step 2 CK. McGraw-Hill Education; 2015.
  • 9. Sander R. Otitis Externa: A Practical Guide to Treatment and Prevention. https://www.aafp.org/afp/2001/0301/p927.html. Updated March 1, 2001. Accessed April 29, 2020.
last updated 07/20/2020
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