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Otitis Externa

Otitis Externa is a topic covered in the 5-Minute Clinical Consult.

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Inflammation of the external auditory canal:

  • Acute diffuse otitis externa: the most common form; an infectious process; usually bacterial; occasionally fungal (10%)
  • Acute circumscribed otitis externa: synonymous with furuncle; associated with infection of the hair follicle, a superficial cellulitic form of otitis externa
  • Chronic otitis externa: same as acute diffuse but of longer duration (>6 weeks)
  • Eczematous otitis externa: may accompany typical atopic eczema or other primary skin conditions
  • Necrotizing malignant otitis externa: an infection that extends into the deeper tissues adjacent to the canal; may include osteomyelitis and cellulitis; rare in children
  • System(s) affected: skin/exocrine
  • Synonym(s): swimmer’s ear


  • Unknown; higher in the summer months and in warm, wet climates
  • Predominant age: all ages
  • Predominant sex: male = female

  • Acute, chronic, and eczematous: common
  • Necrotizing: uncommon

Etiology and Pathophysiology

  • Acute diffuse otitis externa
    • Traumatized external canal (e.g., from use of cotton swab)
    • Bacterial infection (90%): Pseudomonas (67%), Staphylococcus, Streptococcus, gram-negative rods
    • Fungal infection (10%): Aspergillus (90%), Candida, Phycomycetes, Rhizopus, Actinomyces, Penicillium
  • Chronic otitis externa: bacterial infection: Pseudomonas
  • Eczematous otitis externa (associated with primary skin disorder)
    • Eczema
    • Seborrhea
    • Psoriasis
    • Neurodermatitis
    • Contact dermatitis
    • Purulent otitis media
    • Sensitivity to topical medications
  • Necrotizing otitis externa
    • Invasive bacterial infection: Pseudomonas, increasing incidence of methicillin-resistant Staphylococcus aureus (MRSA)
    • Associated with immunosuppression

Risk Factors

  • Acute and chronic otitis externa
    • Traumatization of external canal
    • Swimming
    • Hot, humid weather
    • Hearing aid use
  • Eczematous: primary skin disorder
  • Necrotizing otitis externa in adults
    • Advanced age
    • Diabetes mellitus (DM)
    • Debilitating disease
    • AIDS
    • Immunosuppression
  • Necrotizing otitis externa in children (rare)
    • Leukopenia
    • Malnutrition
    • DM
    • Diabetes insipidus

General Prevention

  • Avoid prolonged exposure to moisture.
  • Use preventive antiseptics (acidifying solutions with 2% acetic acid [white vinegar] diluted 50/50 with water or isopropyl alcohol, or 2% acetic acid with aluminum acetate [less irritating]) after swimming and bathing.
  • Treat predisposing skin conditions.
  • Eliminate self-inflicted trauma to canal with cotton swabs and other foreign objects.
  • Diagnose and treat underlying systemic conditions.
  • Use ear plugs when swimming.

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Stephens, Mark B., et al., editors. "Otitis Externa." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116424/all/Otitis_Externa.
Otitis Externa. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116424/all/Otitis_Externa. Accessed March 20, 2019.
Otitis Externa. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116424/all/Otitis_Externa
Otitis Externa [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 March 20]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116424/all/Otitis_Externa.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Otitis Externa ID - 116424 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116424/all/Otitis_Externa PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -