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Otitis externa

SNOMED: 33934002938 words•Updated 03/03/2026
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Exam Tips

  • Classic OSCE clue: pain on tragal pressure or pinna movement strongly supports otitis externa over otitis media.
  • If the canal is very swollen and you cannot fully see the tympanic membrane, document this and choose drops mindful of possible perforation risk.
  • Think malignant otitis externa in older patients with diabetes/immunocompromise plus severe persistent otalgia, granulation tissue, or cranial neuropathy; this is an urgent ENT referral.
  • Fungal otitis externa is suggested by intense itch with fluffy debris, black dots, or hyphae on otoscopy; compare with standard ENT otoscopy image sets for pattern recognition.
  • Do not overuse ear swabs initially; reserve for severe, recurrent, chronic, treatment-failure, or spreading infection scenarios.

Definition

Otitis externa is inflammation of the external auditory canal skin and subdermis, often extending to the pinna or tympanic membrane. Acute disease is usually rapid in onset (typically under 6 weeks) and commonly bacterial, while chronic disease persists for more than 3 months and may be driven by inflammatory dermatoses, fungal overgrowth, or persistent low-grade infection.

Pathophysiology

The normal ear canal is protected by cerumen, an acidic microenvironment, and an intact epithelial barrier with outward epithelial migration. Moisture, trauma (for example cotton buds/instrumentation), dermatitis, or foreign material disrupt this barrier, raise canal pH, and promote microbial growth and inflammation. Acute otitis externa is most often due to Pseudomonas aeruginosa or Staphylococcus aureus; chronic disease reflects ongoing barrier failure with lichenification/stenosis and sometimes fungal colonization (Aspergillus, Candida), especially after prolonged topical antibiotics/steroids. In malignant (necrotizing) otitis externa, infection (usually Pseudomonas) invades soft tissue and bone at the skull base, causing osteomyelitis and possible cranial neuropathies.

Risk Factors

  • Water exposure (swimming, humid/hot environments, perspiration)
  • Ear canal trauma (cotton buds, scratching, syringing, instrumentation)
  • Underlying skin disease (eczema, psoriasis, seborrhoeic dermatitis)
  • Contact dermatitis (for example neomycin sensitivity, hearing-aid/earplug materials, shampoos/detergents, metals)
  • Ear canal obstruction by debris/excess wax/foreign body
  • Hearing aid or ear plug use
  • Otorrhoea from middle-ear disease via perforation or grommet
  • Diabetes mellitus or immunocompromise
  • Older age (especially for malignant otitis externa)
  • Previous ear surgery or head/neck radiotherapy

Clinical Features

Symptoms

  • Acute: rapid-onset otalgia (often severe), itch, otorrhoea, pain on chewing/jaw movement
  • A sensation of blocked ear with conductive hearing reduction
  • Chronic: persistent itch, mild discomfort, recurrent discharge
  • Malignant otitis externa red flags: unremitting disproportionate pain, headache, fever/malaise, possible vertigo

Signs

  • Tragal and/or pinna tenderness
  • Erythematous, oedematous external canal with debris or purulent/serous discharge
  • Canal narrowing/occlusion; tympanic membrane may be hard to visualize
  • Fungal clues: white strands (Candida) or black/white dots/fluffy debris (Aspergillus)
  • Regional lymphadenitis and cellulitis of adjacent skin
  • Malignant otitis externa: granulation tissue at bone-cartilage junction, exposed bone, cranial nerve deficits (especially facial nerve palsy)

Investigations

Clinical otoscopy (diagnosis is mainly clinical):Diffuse inflamed oedematous ear canal with tenderness and debris/discharge; assess if tympanic membrane perforation or grommet is present
Aural toilet assessment (microsuction/cleaning requirement):Obstructing debris or marked oedema limiting drop penetration; may need wick
Ear swab for microscopy, culture and sensitivity:Not routine initially; useful in severe, recurrent, chronic, treatment-failure, occluded canal, or suspected spread beyond canal
Blood tests and inflammatory markers (if malignant otitis externa suspected):Raised inflammatory markers may support invasive infection
Imaging (CT/MRI/nuclear imaging in secondary care for suspected malignant disease):Evidence of skull-base/temporal bone osteomyelitis or soft tissue extension

Management

Lifestyle Modifications

  • Keep ear dry during treatment (no swimming; protect during showering)
  • Avoid cotton buds, scratching, and self-instrumentation
  • Stop/limit irritants (ear cosmetics, problematic ear plugs/hearing-aid moulds) and manage underlying dermatitis
  • Provide analgesia and safety-net advice; seek urgent review if systemic illness, spreading cellulitis, severe persistent pain, cranial nerve symptoms, or diabetes/immunocompromise with deterioration

Pharmacological Treatment

Analgesia

  • Paracetamol 1 g orally every 4-6 hours as needed (max 4 g/day)
  • Ibuprofen 400 mg orally three times daily with food as needed (if suitable)

Stepwise pain control is important because pain can be severe; check NSAID cautions (renal disease, peptic ulcer, anticoagulation, asthma sensitivity).

Topical acidifying/antiseptic therapy (mild disease)

  • Acetic acid 2% ear spray: 1 spray into affected ear three times daily for at least 7 days (continue up to 14 days if needed)

Useful when infection is mild and canal is patent; can sting on inflamed skin.

Topical antibiotic with corticosteroid (moderate/severe uncomplicated acute otitis externa)

  • Dexamethasone 0.1% + neomycin sulfate 0.5% + acetic acid 2% (e. g. Otomize): 1 spray three times daily, usually 7 days (up to 10 days)
  • Fludrocortisone acetate 0.1 mg/mL + oxytetracycline 10 mg/mL + polymyxin B 10,000 units/mL ear drops: 2-3 drops twice daily
  • Gentamicin 0.3% + hydrocortisone 1% ear drops: 2-3 drops three to four times daily

Reassess if not improving within 48-72 hours. Safety: avoid aminoglycoside-containing drops (neomycin/gentamicin) when tympanic membrane perforation or grommet is present due to ototoxicity risk; consider non-ototoxic quinolone specialist regimens in this setting.

Antifungal therapy (otomycosis/chronic fungal otitis externa)

  • Clotrimazole 1% topical ear preparation (local protocol/off-label in some settings): typically 2-3 drops two to three times daily after aural toilet

Aural toilet is often essential before antifungal treatment; review diagnosis if persistent symptoms.

Systemic antibiotics (only when spread beyond canal or severe disease)

  • Flucloxacillin 500 mg orally four times daily for 5-7 days (if cellulitis/perichondrial involvement and staphylococcal cover needed)
  • Ciprofloxacin 500-750 mg orally twice daily (specialist-guided for malignant otitis externa)

Routine oral antibiotics are not indicated for uncomplicated otitis externa. Ciprofloxacin safety: tendinopathy, QT prolongation, CNS effects, dysglycaemia, C. difficile risk; use only with clear indication and specialist input.

Surgical / Interventional

  • Aural toilet/microsuction to clear debris and improve topical drug delivery
  • Ear wick insertion when canal oedema prevents drop penetration
  • Urgent ENT admission for suspected malignant otitis externa for prolonged antipseudomonal therapy, imaging, and multidisciplinary skull-base management
  • Drainage/debridement if abscess or necrotic tissue develops (selected cases)

Complications

  • Chronic or recurrent otitis externa
  • Periauricular cellulitis, perichondritis/chondritis, abscess formation, parotitis
  • Canal fibrosis/stenosis and conductive hearing loss
  • Myringitis and possible tympanic membrane perforation
  • Malignant otitis externa with temporal/skull-base osteomyelitis
  • Cranial nerve palsies (facial nerve early; lower cranial nerves in advanced disease), meningitis, brain abscess, sepsis

Prognosis

Most uncomplicated acute cases improve within 48-72 hours of appropriate topical therapy, with clinical resolution in roughly 7-10 days for the majority. Chronic otitis externa can relapse and may lead to progressive canal stenosis and hearing impairment. Malignant otitis externa is potentially life-threatening and requires urgent specialist treatment; mortality is substantial in temporal bone osteomyelitis.

Sources & References

🏥BMJ Best Practice(1)

💊BNF Drug References(6)

✅NICE Guidelines(1)

📖Textbook References(20)

  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 630)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 627)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1274)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1274)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 628)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 626)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1600)[context]
  • Netter F. Netter Atlas of Human Anatomy. A Systems Approach 8ed 2022.pdf(pp. 1988, 1989)[context]
  • Netter F. Netter Atlas of Human Anatomy. A Systems Approach 8ed 2022.pdf(pp. 1988, 1989)[context]
  • Netter F. Netter Atlas of Human Anatomy. Classic Regional Approach 8ed 2022.pdf(pp. 230, 231)[context]
  • _OceanofPDF.com_Netters_Anatomy_-_8th_edition_-_Frank_H_Netter_MD.pdf(pp. 1989)[context]
  • Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 673, 674)[context]
  • Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 94, 95)[context]
  • Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 526, 527)[context]
  • Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 526, 527)[context]
  • Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 94, 95)[context]
  • [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 681, 682)[context]
  • [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 681)[context]
  • [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 680, 681)[context]
  • [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 679, 680)[context]

Sources

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