Clinical Notes : ENT

126. Acute Otitis Externa

Acute Otitis Externa




  • Otitis externa is inflammation of the external ear canal

    • Acute if it has lasted for 3 weeks or less.

    • Chronic if it has lasted for longer than 3 months.


  • Diffuse (swimmer's ear, or tropical ear)​

    • widespread inflammation of the skin and subdermis of the external ear canal, which can extend to the external ear and the tympanic membrane (ear drum)


  • ​Localized (furunculosis)

    • infection of a hair follicle that can progress to become a furuncle (boil) in the ear canal


  • Eczematous (eczematoid)

    • Encompasses various dermatologic conditions that may infect the External Auditory Canal 

      • atopic dermatitis

      • psoriasis

      • systemic lupus erythematosus

      • eczema


  • Necrotising (malignant)

    • aggressive infection that spreads into the bone surrounding the ear canal (the mastoid and temporal bones

      • fatal condition without treatment


  • Otomycosis

    • Infection of the ear canal from a fungal species



  • Otitis externa is common and more than 1% of people will be diagnosed with the condition each year.

    • It affects people of all ages, but incidence peaks at age 7–12 years.



  • Bacterial infection

    • most common cause of otitis externa

    • Pseudomonas aeruginosa or Staphylococcus aureus are the most prevalent pathogens.


  • Fungal infections

    • Superficial fungal infection is usually due to Aspergillus species, or Candida albicans.  

    • Deeper infections (of the stratum corneum) are due to epidermophyton, trichophyton, or microsporum genera.


  • Seborrhoeic dermatitis

    • may affect the ears in isolation, or be associated with one or more of the following: dandruff, eyebrow scaling, blepharitis, or facial redness and scaling.


  • Contact dermatitis

    • topical medications (for example neomycin ear drops)

    • hearing aids

    • earplugs.


  • Allergic contact dermatitis 

    • usually has a sudden onset and presents with erythematous, itchy, oedematous, and exudative lesions.


  • Irritant contact dermatitis 

    • tends to have an insidious onset with lichenification.


  • Trauma

    • caused by scratching, aggressive cleaning, ear syringing, foreign objects in the ear, and the use of cotton buds, hearing aids or ear plugs.


  • Environmental factors

    • high temperature and/or high humidity

    • perspiration

    • swimming (especially in polluted water)

  • Regular cleaning of the ear canal

    • alkaline eardrops

    • soapy deposits

    • cerumen creates a slightly acidic pH that inhibits infection (especially by P aeruginosa) but can be altered by water exposure, aggressive cleaning

    • removes cerumen, which is an important barrier to moisture and infection

  • Risk factors for malignant otitis include

    • diabetes

    • radiotherapy to the head and neck.

    • compromised immunity, such as from HIV/AIDS, chemotherapy, or chronic kidney disease



  • Signs:

    • The ear canal or external ear, or both, are red, swollen, or eczematous with shedding of the scaly skin.

    • Swelling in the ear canal is typical of an early presentation of localized otitis externa; later the swelling has a white or yellow centre filled with pus; occasionally this progresses and the swelling eventually completely occludes the ear canal.

    • Discharge (serous or purulent) may be present in the ear canal.

    • Inflamed eardrum, which may be difficult to visualize if the ear canal is narrowed or filled with debris.


  • Symptoms include any combination of the following:

    • Itch (typical). 

    • Severe ear pain, disproportionate to the size of the lesion (typical).

    • Pain made worse when the tragus or pinna is moved, or when an otoscope is inserted (typical).

    • Tenderness on moving the jaw.

    • Tender regional lymphadenitis — may be present (less common).

    • Sudden relief of pain if the furuncle in localized otitis externa bursts (rare).

    • Loss of hearing if there is sufficient swelling to occlude the ear canal (rare).

Diffuse (swimmers ear)

Localised (furunculosis)







  • Treat the pain if present:

    • analgesic

      • paracetamol or ibuprofen

      • plus codeine for severe pain

    • application of local heat (for example a warm flannel).

    • These measures are sufficient for most cases of localized otitis externa as folliculitis is usually mild and self-limiting

  • Topical antimicrobials are beneficial

    • use topical antibiotic with or without a topical corticosteroid

    • use for a minimum of 7 days

      • if symptoms persist, continue up to a maximum of 14 days

    • Quinolone containing preparations (for example ciprofloxacin, or ofloxacin) only require twice daily dosing

      • can be used in people with a perforated ear drum

    • Topical acetic acid 2% spray

      • is safe and effective treatment

      • can be used for mild cases

    • Chloramphenicol ear drops

      • not recommended as they contain propylene glycol which causes contact dermatitis in about 10% of people

  • Only consider an oral antibiotic if

    • medical condition which is associated with increased risk of severe infection (such as diabetes mellitus, or compromised immunity).

    • systemic signs of infection, such as fever.

    • severe infection, or at high risk for severe infection

      • for example if furunculosis or cellulitis spreads beyond the ear canal to the pinna, neck, or face.

    • If an oral antibiotic is required, consider are a 7-day course of flucloxacillin, or clarithromycin (if the person is allergic to penicillin)​


  • If fungal infection is suspected (signs of fungal growth in the ear canal):

    • Prescribe a topical antifungal preparation

      • ​Clotrimazole 1% solution.

      • Acetic acid 2% spray (unlicensed use).

      • Clioquinol and a corticosteroid 

    • Seek specialist advice if there is inadequate response.


  • If the cause is Irritant, or allergic dermatitis

    • avoid contact with the irritant or allergen

    • prescribe a topical corticosteroid.

      • Seborrhoeic dermatitis — treat topically with an antifungal/corticosteroid combination

  • Drain pus

    • if pus is causing severe pain and swelling

      • rarely required.

      • usually requires referral

        • a small pustule near the entrance to the ear canal may be drained by incising it with a surgical needle

  • Manage any aggravating or precipitating factors

    • diabetes mellitus

    • dermatitis

    • ear trauma​


  • Consider the need for investigations

    • ear swab proves rarely useful, but may be necessary if symptoms are persistent or recurrent.


  • Provide appropriate self-care advice to aid recovery and reduce risk of recurrence

    • keep the ears clean and dry

    • avoid the use of cotton buds

  • Treat generalized skin conditions such as eczema


  • Seek specialist advice if

    • symptoms persist

    • contact sensitivity is suspected

    • ear canal is occluded.


  • Refer to secondary care if

    • extensive cellulitis

    • extreme pain or discomfort

    • considerable discharge or extensive swelling of the auditory canal

    • sufficient earwax or debris to obstruct the application of topical medication


  • Follow up  

    • is not usually necessary,

    • recommended for people with 

      • severe otitis externa

      • chronic otitis externa

      • diabetes mellitus

      • compromised immunity.


  • Management of localized otitis externa includes:

    • Advising people to apply local heat using a warm flannel — this may be sufficient, as folliculitis is usually mild and self-limiting.

    • Considering incision and drainage if pus is causing severe pain and swelling — this usually requires referral, although a small pustule near the entrance to the ear canal may be drained by incising it with a surgical needle.


  • Urgent admission should be arranged for people with suspected malignant otitis.



  • Keep ears clean and dry

    • avoid use of cotton buds

    • use a hair dryer (at the lowest heat setting) to dry the ear canal after hair washing, bathing, or swimming

    • swimming

      • use ear plugs and or a tight fitting cap 

      • people with acute otitis externa should abstain from water sports for at least 7 to 10 days

      • consider using acidifying ear drops or spray (such as EarCalm®) shortly before swimming, after swimming, and at bedtime​


Summary tables: infections in primary care

Management and treatment of common infections:

guidance for consultation and adaptation




Acute Otitis Externa

September 2014


NICE CSK Guidelines

Otitis Externa

February 2018


Clinical practice guideline: acute otitis externa

American Academy of Otolaryngology



Otitis Externa

BMJ Best Practice

February 2019



Topical ear preparations available in the ROI for treating otitis externa :


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