Otitis Externa: Diagnosis, Treatment and Prevention

Otitis externa is inflammation of the external auditory canal, sometimes extending to the tragus, pinna or outer surface of the tympanic membrane. Acute diffuse bacterial otitis externa is commonly called swimmer's ear, but swimming is only one of several risk factors. Moisture, trauma from cleaning the ear, skin disease and devices placed in the canal can all damage its normal protective barrier.

The condition may be intensely painful even when the visible changes appear modest. Most uncomplicated cases are treated successfully with careful ear-canal care, effective analgesia and correctly administered topical medication. The clinician must also recognise fungal disease, chronic dermatitis and the dangerous invasive form known as necrotising otitis externa.

High-yield distinction

Pain produced by pressing the tragus or moving the pinna strongly supports otitis externa. In acute otitis media, the main disease is behind the tympanic membrane and tragal or pinna movement is usually much less painful.

Learning objectives

Define and classify acute, chronic, fungal and necrotising otitis externa.
Explain how moisture and trauma disrupt the protective ear-canal barrier.
Recognise the typical history and examination findings.
Select appropriate investigations and distinguish otitis externa from common alternatives.
Outline safe topical treatment, correct drop administration, follow-up and referral.
Identify red flags for necrotising disease and other serious pathology.

Relevant anatomy and natural protection

The external auditory canal carries sound from the pinna to the tympanic membrane. Its outer part contains hair follicles and ceruminous and sebaceous glands, while its inner bony part has thin, tightly adherent skin that is easily injured. Review the structure of the external, middle and inner ear before studying the disease process.

Cerumen Protective wax

Cerumen traps debris, repels water, lubricates the canal and helps maintain an acidic environment that restricts bacterial and fungal growth.

Epithelium Migrating skin barrier

Healthy canal epithelium moves slowly outward, carrying wax and debris away. Scratching, instrumentation and prolonged moisture interrupt this defence.

Canal shape Ventilation and drainage

Narrowing from oedema, congenital stenosis, exostoses or retained material traps moisture and reduces delivery of topical medicine.

Pathophysiology

Barrier disruption: Water, soap, cotton buds, matchsticks, fingernails, earphones or other objects remove wax and cause microscopic skin injury.
Maceration and pH change: Retained moisture softens the epithelium and reduces the canal's normal acidity.
Microbial multiplication: Organisms colonise the damaged skin and produce inflammation, discharge and pain.
Oedema and obstruction: Swelling narrows the canal, causing fullness, temporary conductive hearing loss and poor penetration of drops.

Classification and causes

Type	Typical features	Common causes or associations
Acute diffuse bacterial	Rapid onset of pain, tragal tenderness, canal erythema, oedema and variable discharge.	Pseudomonas aeruginosa and Staphylococcus aureus are important pathogens; infection may be polymicrobial.
Localised otitis externa	A focal, very tender swelling or furuncle in the hair-bearing outer canal.	Often a staphylococcal infection of a hair follicle.
Otomycosis	Intense itching, blocked sensation and characteristic fluffy, black, white or grey debris.	Aspergillus and Candida; favoured by tropical humidity, diabetes, immunosuppression and prolonged antibacterial drops.
Chronic or eczematous	Symptoms persist or recur for three months or more; itching, scaling and thickened canal skin may dominate.	Atopic, seborrhoeic or contact dermatitis, psoriasis, allergy to ear preparations or hearing-aid materials.
Necrotising otitis externa	Severe persistent pain, often worse at night, discharge, granulation tissue and possible cranial neuropathy.	Invasive infection and skull-base osteomyelitis, especially in older people with diabetes or immunocompromise.

Predisposing factors

Swimming, frequent bathing, excessive sweating and a warm humid environment.
Self-cleaning or scratching with cotton buds, hairpins, matchsticks, fingernails or other objects.
Hearing aids, earplugs, earphones or a retained foreign body.
Wax obstruction, a narrow canal, exostoses or previous ear surgery.
Eczema, seborrhoeic dermatitis, psoriasis and allergic contact dermatitis.
Diabetes mellitus, HIV infection, other immunocompromised states or previous radiotherapy.

Clinical presentation

Symptoms

Otalgia: Ear pain may be severe and can worsen with chewing, tragal pressure or pinna movement.
Pruritus: Itching is common and may be particularly prominent in fungal or eczematous disease.
Otorrhoea: Discharge may be scanty or profuse and can vary in colour and consistency.
Aural fullness and reduced hearing: Canal oedema and debris cause a temporary conductive hearing loss.
Tinnitus, tenderness around the ear or discomfort when inserting an earphone or hearing aid.

Examination

Record temperature and general condition. High fever or systemic illness is unusual in uncomplicated disease.
Inspect the pinna, tragus, conchal bowl, mastoid region and surrounding skin for erythema, swelling, trauma, vesicles or cellulitis.
Gently press the tragus and move the pinna. Marked tenderness supports external-canal inflammation.
Use an otoscope gently. The canal may be erythematous, swollen and filled with debris or discharge. Do not force a speculum through a painful narrowed canal.
Assess the tympanic membrane whenever it can be seen. Its integrity determines which drops can be used safely.
Examine the opposite ear and test facial movement and other cranial nerves when disease is severe.
Check regional lymph nodes and look for extension beyond the canal.

Documentation tip

Record the side affected, degree of canal swelling, type of discharge or debris, tragal and pinna tenderness, condition of surrounding skin and whether the tympanic membrane was visualised and appeared intact.

Investigations

Otitis externa is usually a clinical diagnosis. Routine laboratory tests and imaging are unnecessary in a straightforward first episode.

Investigation	When it is useful	Purpose
Ear swab for microscopy, culture and sensitivity	Severe, recurrent or chronic disease; immunocompromise; suspected fungal infection; previous treatment; or failure to improve.	Identifies bacteria or fungi and guides targeted therapy. Collect correctly using the principles in ENT swab collection.
Blood glucose or HbA1c	Known diabetes, suggestive symptoms, recurrent disease or concern for necrotising infection.	Detects or assesses diabetes, an important modifying factor.
FBC, CRP and ESR	Systemic illness, spreading infection or suspected necrotising otitis externa.	Supports assessment of inflammatory activity; results do not replace clinical judgement.
Hearing assessment	Persistent hearing loss, recurrent disease or uncertainty after the canal clears.	Distinguishes temporary canal obstruction from another hearing disorder.
CT or MRI	Not routine; requested urgently by specialists when invasive disease, skull-base osteomyelitis, abscess or another complication is suspected.	Defines bony and soft-tissue spread and helps plan specialist management.

For a broader approach to test selection, see ordering and interpreting ENT investigations.

Differential diagnosis

Acute otitis media

Middle-ear inflammation, usually with an abnormal bulging tympanic membrane. Discharge can occur after perforation, but movement of the tragus and pinna is usually less tender.

Foreign body or trauma

A retained object, insect or abrasion can cause unilateral pain and discharge. Examine carefully and avoid blind instrumentation.

Herpes zoster oticus

Severe otalgia with vesicles in or around the ear; facial weakness, vertigo or hearing symptoms may indicate Ramsay Hunt syndrome.

Mastoiditis

Post-auricular pain, erythema, swelling and protrusion of the pinna suggest mastoid disease rather than isolated canal inflammation.

Cholesteatoma

Persistent, often offensive unilateral discharge and hearing loss require careful examination and ENT referral.

Canal tumour

Persistent unilateral pain, bleeding, granulation tissue or failure to respond to correct treatment requires exclusion of external-canal malignancy.

Management of uncomplicated acute otitis externa

1. Relieve pain

Assess pain formally and provide oral analgesia appropriate for age, pregnancy status, comorbidities and contraindications. Paracetamol or an NSAID such as ibuprofen is commonly used. Severe or worsening pain despite appropriate treatment should trigger reassessment rather than repeated analgesic escalation alone.

2. Protect and clean the canal

Keep the ear dry during treatment. Avoid swimming and prevent water or shampoo entering during bathing.
Stop cotton buds, scratching, probing and unprescribed substances or herbal preparations.
Temporarily avoid hearing aids, earplugs and in-ear earphones in the affected ear until pain and discharge settle.
When discharge or debris obstructs the canal, gentle aural toilet by a trained clinician improves examination and drug delivery.
Avoid blind curettage. Ear irrigation or syringing is unsafe when the tympanic membrane is not known to be intact and should be avoided in severe canal inflammation, diabetes or suspected invasive disease.

3. Use topical treatment as first-line therapy

Topical preparations achieve a high drug concentration at the infected skin. The product is selected according to severity, likely cause, tympanic-membrane status, allergy, local availability and current Uganda Clinical Guidelines or facility formulary.

Mild early disease Acidifying or antiseptic preparation

May be appropriate when the tympanic membrane is confirmed intact. Inflamed or excoriated skin may sting, and unverified home mixtures should not be placed in an ear when perforation is possible.

Bacterial disease Topical antibiotic with or without corticosteroid

A corticosteroid can reduce oedema and itching. Choice depends on the tympanic membrane and local resistance patterns. Follow the exact product instructions.

Possible perforation Use a non-ototoxic preparation

When the membrane is perforated, cannot be visualised, or a ventilation tube is present, a fluoroquinolone preparation such as ofloxacin or ciprofloxacin is generally preferred. Avoid potentially ototoxic aminoglycoside-containing drops unless specifically directed by an ENT specialist.

Otomycosis Canal cleaning plus topical antifungal

Fungal debris should be cleared by a trained clinician. A preparation such as clotrimazole may be selected according to membrane status and local guidance; repeated antibacterial drops alone can worsen fungal overgrowth.

Example guideline regimen

Médecins Sans Frontières lists ciprofloxacin ear drops for 7 days for acute otitis externa, with age- and product-specific drop numbers. Use the locally available formulation and its official instructions; do not assume that every product has the same concentration or dose.

Oral or injectable antibiotics are not routine initial treatment for uncomplicated diffuse otitis externa. Consider systemic therapy and specialist advice when infection spreads beyond the canal, the patient is systemically unwell, important host factors are present, or topical delivery is impossible.

4. Improve delivery of drops

Wash hands and warm the bottle in the hand; very cold drops may cause dizziness.
Lie with the affected ear facing upward.
In adults, gently pull the pinna upward and backward; in a young child, pull it downward and backward.
Instil the prescribed number of drops without touching the applicator to the ear.
Gently move the pinna or press the tragus to help the medicine enter, then remain on the side for three to five minutes.
Do not seal the canal with tissue or cotton after administration.

If marked swelling prevents drops reaching the canal, a trained clinician may insert an ear wick. The wick is moistened with medication and usually reviewed or removed after 48–72 hours. It should not be inserted blindly or left without follow-up.

5. Reassess

Improvement in pain, itching and fullness should normally begin within 48–72 hours, although complete resolution can take longer. Failure to improve requires confirmation of the diagnosis, assessment of adherence and drop technique, repeat examination for obstruction, consideration of culture and exclusion of fungal, dermatological, invasive or neoplastic disease.

Chronic and recurrent otitis externa

Chronic disease is often driven by eczema, psoriasis, seborrhoeic dermatitis, contact allergy or continuing trauma rather than uncontrolled bacterial infection alone. Management includes:

Identifying and avoiding shampoo, hair products, earphones, hearing-aid moulds or topical medicines that trigger contact dermatitis.
Stopping a sensitising preparation, particularly when itching and a rash worsen during treatment.
Gentle skin care, appropriate emollients or a short course of a prescribed topical corticosteroid when dermatitis is confirmed.
Culture or mycology when discharge persists and targeted antimicrobial treatment only when infection is demonstrated or strongly suspected.
ENT or dermatology assessment for recurrent, stenosing or diagnostically uncertain disease.

Necrotising otitis externa

Necrotising otitis externa, formerly called malignant otitis externa, is an aggressive infection that spreads from the external canal to the temporal bone and skull base. “Malignant” describes its destructive behaviour; it does not mean cancer. Pseudomonas aeruginosa is a major cause, although other bacteria and fungi can occur.

Emergency red flags

Older patient with diabetes, immunocompromise or previous radiotherapy.
Deep severe pain, especially nocturnal pain or pain out of proportion to visible findings.
Persistent purulent or offensive discharge despite correct topical therapy.
Granulation tissue or exposed bone in the floor of the ear canal.
Facial weakness, dysphagia, hoarseness or another cranial-nerve abnormality.
Spread beyond the canal, systemic illness or markedly elevated inflammatory markers.

Action: Arrange same-day emergency ENT or hospital assessment. Do not manage suspected necrotising disease as routine swimmer's ear.

Specialist assessment may include microscopy, deep culture or biopsy, blood glucose, ESR/CRP and CT or MRI. Treatment is prolonged, culture-directed systemic antipseudomonal therapy with multidisciplinary management of diabetes or immunosuppression. Surgery is reserved for selected refractory disease or diagnostic tissue sampling.

Complications

Temporary conductive hearing loss from canal oedema and debris.
Periauricular cellulitis, pinna perichondritis or local abscess.
Chronic inflammation, canal thickening and acquired stenosis.
Recurrent bacterial or fungal infection.
Contact allergy to topical preparations.
Skull-base osteomyelitis and cranial-nerve palsies in necrotising disease.

Prevention and patient education

Do not insert cotton buds, pens, keys, matchsticks, hairpins or fingers into the ear canal.
Allow water to drain after swimming or bathing and dry only the outer ear gently.
A hair dryer on the lowest cool or warm setting may be held several centimetres away to help dry a moisture-prone ear.
Do not remove protective wax unless it is causing symptoms or preventing necessary examination.
Keep hearing aids and earphones clean, dry and well fitting; stop using them temporarily during active painful infection.
Seek review for recurrent symptoms so that diabetes, dermatitis, fungal infection or anatomical narrowing can be addressed.
Never use drying or acidifying drops when a perforated tympanic membrane, ventilation tube, ear operation or active discharge is possible unless a clinician has advised them.

Nursing and primary-care responsibilities

Assess pain, fever, diabetes or immunocompromise and screen for red flags at the first contact.
Inspect gently with appropriate basic ENT instruments and document whether the tympanic membrane is visible.
Administer analgesia and prescribed ear drops safely, then teach and observe the patient's technique.
Keep the ear dry; avoid packing the canal with ordinary cotton wool after drops.
Do not perform forceful irrigation or instrumentation when contraindicated.
Arrange review within 48–72 hours when symptoms are severe, risk factors exist or improvement is uncertain.
Escalate facial weakness, severe nocturnal pain, spreading cellulitis, systemic illness or suspected necrotising disease immediately.

Clinical reasoning example

Scenario: A 22-year-old presents after several days of swimming with severe right ear pain, itching and scanty discharge. Pressing the tragus and moving the pinna are very painful. The canal is swollen and red; the patient is afebrile and otherwise well.

Most likely diagnosis: Acute diffuse otitis externa.
Important assessment: Look for diabetes or immunocompromise, extension beyond the canal and possible tympanic-membrane perforation.
Initial management: Oral analgesia, dry-ear precautions, gentle clearance of obstructing debris when skilled care is available, and an appropriate topical preparation.
Do not: Prescribe an oral antibiotic routinely, force an otoscope through the swollen canal or advise unverified substances in the ear.
Follow-up: Reassess if there is no clear improvement within 48–72 hours or sooner if pain worsens, fever develops or facial movement changes.

Knowledge-check summary

Key examination points

Otitis externa affects the external auditory canal; tragal and pinna tenderness are characteristic.
Moisture and trauma disrupt cerumen and canal epithelium, allowing infection.
Pseudomonas aeruginosa and Staphylococcus aureus are major bacterial causes.
Uncomplicated acute disease is treated primarily with topical therapy, not routine oral antibiotics.
Aural toilet and an ear wick can improve delivery when debris or oedema blocks the canal.
Use a non-ototoxic preparation when tympanic-membrane perforation is known or suspected.
No improvement within 48–72 hours requires reassessment.
Severe nocturnal pain, granulation tissue or cranial neuropathy in a patient with diabetes or immunocompromise suggests necrotising otitis externa and requires emergency referral.

Doctors Revision

Otitis Externa: Diagnosis, Treatment and Prevention