• 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.


  • Most cases of otitis externa are infectious in origin.
  • Non-infectious forms of otitis externa are less common and include seborrheic otitis externa (which is associated with seborrheic otitis externa), eczematous otitis externa (a hypersensitivity reaction to pathogens or topical antibiotics), and neurodermatitis (caused by compulsive/psychogenic scratching).


Clinical features

  • Symptoms
    • Severe ear pain, particularly at night
    • Otorrhea
    • Intense itching in the external auditory canal
  • Signs


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)!



  • 1. Waitzman AA. Otitis Externa Medication. In: Otitis Externa Medication. New York, NY: WebMD. http://emedicine.medscape.com/article/994550-overview. Updated July 11, 2016. Accessed February 15, 2017.
  • 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.
last updated 09/28/2018
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