Otitis externa

Last updated: August 12, 2022

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Otitis externa (OE) is an inflammation of the external auditory canal (EAC), which is most often the result of a local bacterial infection. Risk factors for OE include exposure to water and injury to the skin of the EAC. OE is primarily a clinical diagnosis. It is characterized by ear pain, fullness, and/or itching, and tenderness of the tragus and/or pinna; otoscopy may show erythema, edema, debris, and/or otorrhea of the EAC. Treatment typically involves analgesia, keeping the EAC dry, and administering antiseptic, antibiotic, or glucocorticoid ear drops. Systemic antibiotic therapy is indicated in select cases, e.g., patients with immunosuppression and/or diabetes who are at risk of a more severe variant, malignant otitis externa. Malignant otitis externa is commonly caused by Pseudomonas aeruginosa, typically manifests with severe ear pain, and may lead to osteomyelitis of the skull base and subsequent complications such as cranial neuropathies. Immediate referral, diagnosis, and treatment with systemic antipseudomonal antibiotics are necessary.

Acute otitis externa [2][3]

Chronic otitis externa [4]

Symptoms [3]

Examination findings [2][3]

Otoscopy [3]

Severe edema of the EAC may prevent otoscopic examination.

Malignant otitis externa (necrotizing otitis externa) [3][5]

Malignant otitis externa (MOE) is a necrotizing inflammation of the EAC that may lead to osteomyelitis of the skull base.

Etiology [5][6]

Clinical features of MOE [3][5]

Diagnostics of MOE [3][5][9]

All patients require laboratory studies and imaging.

  • Laboratory studies [5]
  • Imaging: More than one modality is often required. [5]
    • Modalities [9]
      • CT head with IV contrast: preferred initial study
      • MRI head: best modality for detecting soft tissue extension and intracranial abnormalities
      • Radionuclide scans: may be useful for early detection [9][10]
      • PET/CT scan: helpful for diagnosis and monitoring treatment response
    • Findings
  • Surgical biopsy: Consider if there is diagnostic uncertainty or insufficient response to treatment. [5]

A negative CT scan does not exclude early MOE, as changes may not be evident until one-third of bone mineral is eroded. [11]

Treatment [3][5]

Treatment involves early empiric antibiotic therapy, prompt otolaryngology consult, and the control of risk factors for MOE, e.g., diabetes or immunosuppression.

Patients unresponsive to antibiotic therapy may require a surgical biopsy to rule out fungal etiology or malignancy. [5]

Complications [8]

Prognosis [5]

  • Overall mortality: < 10%
  • Rates may be higher in patients aged over 80 years or with significant comorbidities.

MOE is a severe infection that can be lethal without prompt treatment. Death is most commonly caused by intracranial complications. [11][13]

Localized otitis externa (furunculosis) [3]

Localized OE is an infection of a hair follicle in the distal EAC.

Etiology [12]



Otomycosis (fungal otitis externa) [3]

Etiology [3]


Treatment [3]

General principles [3]

  • Diagnosis is clinical; AOE is likely if all of the following are present : [1][3]
    • Rapid onset of symptoms (typically within 48 hours) within the last 3 weeks
    • Symptoms of EAC inflammation (i.e., otalgia, pruritus, and/or fullness)
    • Examination findings of EAC inflammation (i.e., pinnal and/or tragal tenderness)
  • Diagnostic studies are only performed:

Diagnostic studies [3]

Differential diagnosis of otitis externa [2][3]
Condition Clinical features
Otitis media
Herpes zoster oticus
Temporomandibular joint (TMJ) syndrome

The differential diagnoses listed here are not exhaustive.

The following applies to diffuse AOE. For the treatment of localized OE, otomycosis, and MOE, see “Subtypes and Variants.” COE is treated according to its etiology, e.g., fungal, allergic, or autoimmune. [16]

Approach [2][3]

If patients do not respond to initial topical therapy, consider alternative diagnoses such as allergic contact dermatitis from an ototopical agent, otomycosis, or MOE. [3]

Supportive therapy [3]

Aural toilet can be painful for patients with severe inflammation; give analgesia beforehand and consider procedural sedation. [3]

Do not perform aural toilet in patients without a confirmed intact TM or with risk factors for MOE (e.g., older adults, patients with diabetes or immunosuppression). [3]

Antimicrobial treatment

Systemic antibiotics for OE [2][3]

Topical antimicrobials for OE [2][3]

  • Choice of agent
    • Multiple options are effective; choose based on patient factors, preference, cost, etc.
    • Glucocorticoids (included in some preparations) may speed up symptom improvement.
  • Treatment duration [3]
    • Typically 7 days; may be extended up to 10–14 days if needed
    • Patients with persistent symptoms at 14 days should be reassessed.
Topical antimicrobial therapy for acute otitis externa [2][3]
Agents Considerations
  • Avoid if the TM:
    • Is not intact
    • Cannot be visualized
  • May be painful or irritating (affecting adherence)
  • Possible efficacy if used for > 7 days
  • Avoid if the TM:
    • Is not intact
    • Cannot be visualized
  • Increased risk of allergic contact dermatitis; avoid in recurrent AOE.
  • The high dosing frequency may impact adherence.

If allergic contact dermatitis secondary to ototopical agents (e.g., neomycin) is suspected, discontinue the agent and treat with a topical glucocorticoid. [2]

Use quinolones in patients with nonintact (perforated or tympanostomy tube) TM or if the TM cannot be visualized; use of other topical agents risks iatrogenic hearing loss. [3]

Indications [19]

Interventions [2][20]

  • Avoid manipulation of the ear canal (e.g., use of cotton buds to clean the ear).
  • Regularly remove and clean earrings and in-ear devices, e.g., hearing aids.
  • Treat underlying chronic dermatological conditions.
  • Frequent swimmers: Use a tight-fitting bathing cap or ear plugs. [3][21]
  • After bathing or swimming:
    • Tilt the head to remove water.
    • Dry the ear with a blow-dryer at the lowest heat setting.
  • Consider prophylactic use of acetic acid ear drops. [2]
  1. Smith ME, Hardman JC, Mehta N, et al. Acute otitis externa: Consensus definition, diagnostic criteria and core outcome set development.. PLoS ONE. 2021; 16 (5): p.e0251395. doi: 10.1371/journal.pone.0251395 . | Open in Read by QxMD
  2. Schaefer P, Baugh RF. Acute otitis externa: an update.. Am Fam Physician. 2012; 86 (11): p.1055-61.
  3. Rosenfeld RM, Schwartz SR, Cannon CR, et al. Clinical Practice Guideline: Acute Otitis Externa. Otolaryngol Head Neck Surg. 2014; 150 (1_suppl): p.S1-S24. doi: 10.1177/0194599813517083 . | Open in Read by QxMD
  4. Magliocca KR, Vivas EX, Griffith CC. Idiopathic, Infectious and Reactive Lesions of the Ear and Temporal Bone. Head Neck Pathol. 2018; 12 (3): p.328-349. doi: 10.1007/s12105-018-0952-0 . | Open in Read by QxMD
  5. Durand ML. Infections of the Ears, Nose, Throat, and Sinuses. Springer International Publishing ; 2018 : p. 115-131
  6. Byun YJ, Patel J, Nguyen SA, Lambert PR. Necrotizing Otitis Externa: A Systematic Review and Analysis of Changing Trends. Otol Neurotol. 2020; 41 (8): p.1004-1011. doi: 10.1097/mao.0000000000002723 . | Open in Read by QxMD
  7. Hobson CE, Moy JD, Byers KE, Raz Y, Hirsch BE, McCall AA. Malignant Otitis Externa: Evolving Pathogens and Implications for Diagnosis and Treatment. Otolaryngol Head Neck Surg. 2014; 151 (1): p.112-116. doi: 10.1177/0194599814528301 . | Open in Read by QxMD
  8. Carfrae MJ, Kesser BW. Malignant Otitis Externa. Otolaryngol Clin North Am. 2008; 41 (3): p.537-549. doi: 10.1016/j.otc.2008.01.004 . | Open in Read by QxMD
  9. Khan HA. Necrotising Otitis Externa: A Review of Imaging Modalities. Cureus.. 2021 . doi: 10.7759/cureus.20675 . | Open in Read by QxMD
  10. Sturm JJ, Stern Shavit S, Lalwani AK. What is the Best Test for Diagnosis and Monitoring Treatment Response in Malignant Otitis Externa?. Laryngoscope. 2020; 130 (11): p.2516-2517. doi: 10.1002/lary.28609 . | Open in Read by QxMD
  11. Handzel O, Halperin D. Necrotizing (malignant) external otitis.. Am Fam Physician. 2003; 68 (2): p.309-12.
  12. Klein JO. Otitis Externa, Otitis Media, and Mastoiditis. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 2015 : p.767-773.e1. doi: 10.1016/b978-1-4557-4801-3.00062-x . | Open in Read by QxMD
  13. Kaya I, Sezgin B, et al. Malignant Otitis Externa: A Retrospective Analysis and Treatment Outcomes. Turk Arch Otorhinolaryngol. 2018; 56 (2): p.106-110. doi: 10.5152/tao.2018.3075 . | Open in Read by QxMD
  14. Saniasiaya J, Narayanan P. Hyphae in external auditory canal. BMJ Case Reports. 2021; 14 (7): p.e245388. doi: 10.1136/bcr-2021-245388 . | Open in Read by QxMD
  15. Vennewald I, Klemm, E. Otomycosis: Diagnosis and treatment. Clin Dermatol. 2010; 28 (2): p.202-211. doi: 10.1016/j.clindermatol.2009.12.003 . | Open in Read by QxMD
  16. Kesser BW. Assessment and management of chronic otitis externa. Curr Opin Otolaryngol Head Neck Surg. 2011; 19 (5): p.341-347. doi: 10.1097/moo.0b013e328349a125 . | Open in Read by QxMD
  17. Reactions Weekly. FDA taking action against unapproved ear drops. Reactions Weekly. 2015; 1560 (1): p.4-4. doi: 10.1007/s40278-015-3376-6 . | Open in Read by QxMD
  18. Walls R, Hockberger R, Gausche-Hill M. Rosen's Emergency Medicine. Elsevier Health Sciences ; 2018
  19. Osguthorpe JD, Nielsen DR. Otitis externa: Review and clinical update.. Am Fam Physician. 2006; 74 (9): p.1510-6.
  20. 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.
  21. Cassaday K, Vazquez G, Wright JM. Ear Problems and Injuries in Athletes. Curr Sports Med Rep. 2014; 13 (1): p.22-26. doi: 10.1249/jsr.0000000000000020 . | Open in Read by QxMD

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