Acute otitis externa (AOE) is an inflammatory condition of the external auditory canal, most commonly caused by Pseudomonas aeruginosa and Staphylococcus aureus, presenting with rapid-onset otalgia, canal edema, erythema, and otorrhea. [1-2] It is treated primarily with topical antimicrobials and analgesics. [3]
1. History
- Ear pain (otalgia): Onset, severity, laterality, radiation; worsened by chewing or jaw movement
- Otorrhea: Color, consistency, odor, volume
- Itching: Often an early symptom; may precede pain
- Hearing changes: Subjective hearing loss from canal edema/debris
- Timing and triggers: Recent swimming ("swimmer's ear"), water exposure, humid climate, ear instrumentation (cotton swabs, hearing aids, earbuds, earplugs) [1][4]
- Prior episodes: Recurrence suggests chronic otitis externa or underlying dermatologic condition
- Recent ear procedures: Tympanostomy tubes, ear irrigation, ear candling
- Important negatives: Absence of fever, facial weakness, vertigo, severe headache (helps exclude complicated disease)
2. Alarm Features
- Severe, disproportionate otalgia (pain out of proportion to exam) — raises concern for necrotizing (malignant) otitis externa (NOE) [5]
- Granulation tissue at the bony-cartilaginous junction of the ear canal — hallmark of NOE [3][6]
- Cranial nerve deficits, especially facial nerve palsy (CN VII most common; CN IX, X, XI also possible) [3][7]
- Failure to improve after 48–72 hours of appropriate topical therapy [3]
- Fever, systemic toxicity, or periauricular cellulitis extending beyond the canal
- Immunocompromised state or poorly controlled diabetes in the setting of refractory otitis externa [3][8]
- Neurologic symptoms (headache, seizures, altered mental status) — suggest intracranial extension [8]
3. Medications
First-line topical agents (no single preparation is clinically superior to another): [1][9]
The following table summarizes common topical otic preparations:
- Fluoroquinolone-based drops (ciprofloxacin/dexamethasone, ofloxacin): Preferred when tympanic membrane is non-intact (not ototoxic) [2-3]
- Neomycin/polymyxin B/hydrocortisone (Cortisporin): Reasonable first-line when TM is intact; risk of contact dermatitis (~15% sensitization rate to neomycin) [4]
- Acetic acid 2%: Inexpensive option; also useful for prophylaxis [1]
- Addition of topical corticosteroid may hasten symptom resolution (faster otalgia resolution) [2]
- Oral antibiotics: Reserved only for infection extending beyond the ear canal, periauricular cellulitis, or immunocompromised/diabetic patients at risk for progression [1][3]
- Analgesics: NSAIDs or acetaminophen; consider short-course opioids for severe pain per AAO-HNS guidelines [3]
- Contraindicated: Aminoglycoside-containing drops (neomycin, gentamicin) with known or suspected TM perforation due to ototoxicity risk [9]
4. Diet
- No specific dietary triggers or restrictions for uncomplicated AOE
- Hydration is generally supportive
- In diabetic patients with AOE, strict glycemic control is essential to prevent progression to NOE [3][7]
5. Review of Systems
- ENT: Hearing loss, tinnitus, aural fullness, vertigo, facial asymmetry, sore throat, trismus
- Neurologic: Headache, facial weakness/numbness, vision changes, altered mentation (red flags for NOE/intracranial extension)
- Constitutional: Fever, chills, malaise, weight loss
- Dermatologic: Eczema, psoriasis, seborrhea (underlying dermatologic conditions predispose to chronic OE)
- Immunologic: HIV status, chemotherapy, transplant medications
6. Collateral History and Family History
- Collateral: Confirm water exposure history, use of hearing aids/earbuds, ear cleaning habits, prior ear surgeries, recent travel to tropical climates
- Family history: Atopic dermatitis, eczema, psoriasis (predispose to chronic OE)
- Social context: Occupation (swimmers, divers, surfers), recreational water activities
7. Risk Factors
- Water exposure (swimming, bathing, humid environments) — most common precipitant [1][8]
- Ear canal trauma from cotton swabs, fingernails, hearing aids, earbuds, earplugs [4][8]
- Narrow or hairy ear canals (impaired cerumen migration)
- Dermatologic conditions: Eczema, psoriasis, seborrheic dermatitis [4]
- Diabetes mellitus (especially poorly controlled) — major risk factor for NOE [3][5]
- Immunosuppression: HIV/AIDS, chemotherapy, organ transplant [3]
- Prior radiotherapy to the head/neck [3]
- Advanced age [5]
- Absence of cerumen (loss of protective acidic barrier)
8. Differential Diagnosis
- Acute otitis media (AOM): Middle ear effusion, no tragal tenderness; differentiate with pneumatic otoscopy (decreased TM mobility in AOM) [1][8]
- Malignant (necrotizing) otitis externa: Granulation tissue, cranial nerve palsies, severe pain, immunocompromised host — medical emergency [3][5]
- Otomycosis: Itching predominant, thick fungal debris, less edema; caused by Aspergillus or Candida [1][8]
- Contact dermatitis: Allergic reaction to hearing aids, earbuds, metals, otic drops (especially neomycin); itching predominant [1]
- Furunculosis: Focal infection/abscess in lateral canal; may progress to diffuse OE [1]
- Ramsay Hunt syndrome: Herpetic vesicles in canal, facial nerve palsy, severe pain, loss of taste [1]
- Chronic suppurative otitis media: Chronic otorrhea through non-intact TM [1]
- Referred pain: TMJ dysfunction, dental pathology, pharyngeal pathology — normal ear exam [1]
- Ear canal carcinoma: Rare; consider if chronic non-healing lesion or mass
9. Past Medical History
- Diabetes mellitus — critical to identify; risk for NOE [3]
- Immunocompromising conditions (HIV, malignancy, transplant)
- Prior otitis externa episodes — recurrence suggests predisposing factors or chronic OE
- Prior ear surgery (tympanoplasty, mastoidectomy, tympanostomy tubes) — affects TM integrity and drop selection
- History of radiation therapy to head/neck
- Dermatologic conditions (eczema, psoriasis)
- Allergies to otic medications (especially neomycin)
10. Physical Exam
- Vital signs: Fever suggests complicated disease or alternative diagnosis
- Tragal tenderness and pain with pinna manipulation — classic hallmark finding of AOE [1][8]
- Otoscopy:
- Diffuse ear canal edema, erythema, debris/discharge
- Assess TM integrity (critical for drop selection); use pneumatic otoscopy to differentiate from AOM [8]
- Granulation tissue at bony-cartilaginous junction — pathognomonic for NOE [3][6]
- Fungal elements (white/black spores) suggest otomycosis
- Vesicles suggest Ramsay Hunt syndrome
- Periauricular exam: Cellulitis, lymphadenopathy, auricular swelling
- Cranial nerve exam: Facial nerve (CN VII) function — asymmetry is a red flag for NOE [3][7]
- Severity grading: Mild (itching, minimal discomfort) → Moderate (partial canal occlusion, moderate pain) → Severe (complete canal occlusion, intense pain, periauricular involvement)
11. Lab Studies
- Uncomplicated AOE: No labs needed — diagnosis is clinical [8]
- If NOE suspected:
- ESR (>26 mm/h has LR+ of 10.15 for NOE) and CRP (>10 mg/L has LR+ of 8.25) — most useful ED parameters for distinguishing NOE [10]
- CBC with differential
- Blood glucose / HbA1c — assess diabetic control
- BUN, creatinine, albumin — markers associated with worse outcomes in NOE [11]
- Ear canal culture — obtain if refractory to treatment or NOE suspected [5]
12. Imaging
- Uncomplicated AOE: No imaging indicated — diagnosis is entirely clinical [8]
- If NOE/complicated OE suspected:
- CT temporal bone with IV contrast — first-line; demonstrates bony erosion, soft tissue extension, skull base involvement [5][8]
- MRI — superior for soft tissue, dural, and intracranial involvement [8]
- Tc-99m bone scintigraphy — highly sensitive for osteomyelitis but remains positive after clinical resolution; gallium scan can document treatment response [7-8]
- The ACR Appropriateness Criteria rate imaging as "usually not appropriate" for uncomplicated otitis externa [8]
13. Special Tests
- Pneumatic otoscopy or tympanometry: Differentiate AOE from AOM (TM mobility preserved in AOE, reduced in AOM) [8]
- Ear canal culture and sensitivity: Indicated for refractory cases, immunocompromised patients, or suspected NOE [5]
- Biopsy of granulation tissue: If malignancy or NOE suspected — rule out squamous cell carcinoma [6]
- Wick placement: Not a diagnostic test but a therapeutic maneuver for severely edematous canals that cannot accept drops [3][9]
14. ECG
- Not routinely indicated for otitis externa
- Consider ECG only if systemic sepsis from complicated NOE or if planning IV antipseudomonal therapy with QT-prolonging agents (e.g., fluoroquinolones)
15. Assessment
Acute otitis externa is a clinical diagnosis defined by rapid onset (<48 hours) of ear canal inflammation with at least one symptom (otalgia, itching, fullness) and one sign (tragal tenderness, canal edema, erythema, otorrhea). [3][8]
- Severity stratification:
- Mild: Minimal discomfort, itching, mild edema
- Moderate: Intermediate pain, partial canal obstruction
- Severe: Intense pain, complete canal occlusion, periauricular extension
- Typical presentation: Young adult or child with recent water exposure, ear pain worsened by tragal pressure, canal edema and debris
- Atypical presentations: Elderly diabetic with disproportionate pain (think NOE); bilateral OE (think dermatologic cause); itching without pain (think otomycosis or contact dermatitis)
- Complications: Periauricular cellulitis, canal stenosis, TM perforation, progression to NOE/skull base osteomyelitis [8-9]
16. Treatment Plan
Initial management
- Aural toilet: Gentle dry-mopping or suction clearance of debris to allow topical medication delivery [3][9]
- Wick placement: If canal is too edematous for drops to penetrate; remove or replace in 48–72 hours [3]
Topical therapy (7–10 days)
- TM intact: Neomycin/polymyxin B/hydrocortisone (Cortisporin) 3–4 drops TID-QID, or ciprofloxacin/dexamethasone (Ciprodex) 4 drops BID [1][12]
- TM perforated or uncertain: Use non-ototoxic fluoroquinolone drops — ofloxacin 0.3% (5–10 drops daily) or ciprofloxacin/dexamethasone [3][13]
- Drop administration technique: Warm bottle in hands, lie with affected ear up, instill drops, pump tragus to facilitate entry, remain in position 60 seconds [12]
Pain management
- NSAIDs (ibuprofen 400–600 mg q6–8h) or acetaminophen as first-line
- Short-course opioids for severe pain [3]
Systemic antibiotics (only when indicated)
- Periauricular cellulitis, extension beyond canal, immunocompromised, or diabetic patients at high risk [1][3]
- Oral fluoroquinolone (ciprofloxacin 500 mg BID) covers Pseudomonas
NOE management
- IV antipseudomonal antibiotics (e.g., ciprofloxacin IV, piperacillin-tazobactam, or ceftazidime) for weeks [7][14]
- Urgent ENT consultation
- Optimize glycemic control [14]
17. Disposition
- Discharge: Vast majority of uncomplicated AOE — outpatient management with topical therapy [1]
- Observation/admission criteria:
- Periauricular cellulitis requiring IV antibiotics
- Suspected NOE (granulation tissue, cranial nerve deficits, immunocompromised with refractory symptoms)
- Systemic toxicity or sepsis
- ENT consultation triggers:
- Failure to respond to appropriate therapy within 48–72 hours [3]
- Suspected NOE or canal mass
- Need for aural toilet/debridement beyond primary care capability
- Recurrent or chronic otitis externa
18. Follow Up / Return Precautions
- Follow-up: Reassess in 48–72 hours if no improvement; otherwise at completion of therapy (7–10 days) [3]
- Return immediately for:
- Worsening pain despite treatment
- Facial weakness or numbness
- High fever, severe headache, or neurologic symptoms
- Spreading redness/swelling beyond the ear
- Patient counseling:
- Keep ears dry during treatment (use cotton ball with petroleum jelly during bathing; avoid swimming) [1][4]
- Do not insert objects into the ear canal (cotton swabs, bobby pins)
- Complete full course of drops even if symptoms improve
- Prevention: Dry ears after swimming, consider prophylactic acetic acid drops or 1:1 rubbing alcohol/white vinegar after water exposure [1]
- Expected recovery: Most patients improve within 48–72 hours and resolve within 7–10 days with appropriate topical therapy [1]
- NOE follow-up: Requires prolonged monitoring (at least 1 year post-treatment) with serial imaging and inflammatory markers [7]
References
1. Acute Otitis Externa: Rapid Evidence Review. — Jackson EA, Geer K. American Family Physician. 2023.
2. Efficacy and Safety of Ciprofloxacin Plus Fluocinolone Acetonide Among Patients With Acute Otitis Externa: A Randomized Clinical Trial. — Chu L, Acosta AM, Aazami H, et al. JAMA Network Open. 2022.
3. Clinical Practice Guideline: Acute Otitis Externa. — Rosenfeld RM, Schwartz SR, Cannon CR, et al. Otolaryngology--Head and Neck Surgery : Official Journal of American Academy of Otolaryngology-Head and Neck Surgery. 2014.
4. Acute Otitis Externa: An Update. — Schaefer P, Baugh RF. American Family Physician. 2012.
5. An Emergency Medicine-Focused Review of Malignant Otitis Externa. — Long DA, Koyfman A, Long B. The American Journal of Emergency Medicine. 2020.
6. Otitis Externa and Malignant Otitis Externa-for the Hospitalist/Internist. — Patel S, Owen GS, Vivas EX. The Medical Clinics of North America. 2026.
7. Malignant Otitis Externa: An Updated Review. — Treviño González JL, Reyes Suárez LL, Hernández de León JE. American Journal of Otolaryngology. 2021.
8. ACR Appropriateness Criteria® Inflammatory Ear Disease. — Agarwal M, Juliano AF, Hagiwara M, et al. Journal of the American College of Radiology : JACR. 2025.
9. Interventions for Acute Otitis Externa. — Kaushik V, Malik T, Saeed SR. The Cochrane Database of Systematic Reviews. 2010.
10. Necrotizing External Otitis: Diagnostic Clues in the Emergency Department. — Vaca M, Medina MM, Cordero AI, et al. European Archives of Oto-Rhino-Laryngology : Official Journal of the European Federation of Oto-Rhino-Laryngological Societies : Affiliated With the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery. 2024.
11. Predictive Factors for Facial Nerve Palsy in Malignant Otitis Externa: A TriNetX Data Analysis. — Isildak H. The Journal of Laryngology and Otology. 2026.
12. FDA Drug Label. — Updated date: 2025-01-31. Food and Drug Administration.
13. FDA Drug Label. — Updated date: 2024-10-31. Food and Drug Administration.
14. Patient Cases With Malignant Otitis Externa at the University Clinic of Ludwig Maximilians University Munich From 2009 Until 2020. — Stocker M, Hempel JM. Scientific Reports. 2025.