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 (details on malignant otitis externa are covered in a separate article).
- Acute otitis externa (AOE): inflammation of the EAC lasting < 6 weeks 
- Chronic otitis externa (COE): inflammation of the EAC lasting at least 6 weeks to 3 months 
Acute otitis externa 
Bacterial infections (most common cause of otitis externa)
- Pseudomonas aeruginosa (∼ 40% of cases), commonly from swimming activities
- Staphylococcus aureus, Proteus mirabilis, Escherichia coli
- Viral infections (rare): Herpes zoster, influenza viruses
- Fungal infections (less common): Aspergillus (accounts for 90% of all fungal otitis externa), Candida
- Bacterial infections (most common cause of otitis externa)
Noninfectious causes (less common)
- Seborrheic otitis externa (associated with seborrheic dermatitis)
- Eczematous otitis externa (a hypersensitivity reaction to pathogens or topical antibiotics)
- Neurodermatitis (caused by compulsive/psychogenic scratching).
- Injury to the skin of the EAC (e.g., cleaning, insertion of foreign objects such as hearing aids or earplugs, excessive itching)
- Increased moisture in the EAC (e.g., swimming, humid climate)
- Immunosuppression, e.g., diabetes, HIV
Chronic otitis externa 
- Refractory fungal or bacterial infection
- May be associated with autoimmune diseases, e.g.:
- Severe ear pain, particularly at night
- Intense itching in the EAC
- Hearing loss
- Jaw pain 
Examination findings 
- Tenderness on palpation of the tragus
- Pulling up and back on the auricle causes pain.
- The following may also be present:
- Crusting of otorrhea at the entrance to the EAC
- Conductive hearing loss
- Clinical features of cellulitis
- Regional lymphadenitis
- Erythematous and edematous EAC
- Otorrhea or debris
- EAC may be occluded by a furuncle, impacted cerumen, or foreign body
- The tympanic membrane may be erythematous but should not bulge.
Severe edema of the EAC may prevent otoscopic examination.
Subtypes and variants
See also “Malignant otitis externa."
Localized otitis externa (furunculosis) 
Localized OE is an infection of a hair follicle in the distal EAC.
- S. aureus (most common)
- Group A Streptococcus
- Clinical diagnosis
- In addition to classic clinical features of OE, a pustular lesion may be present.
- Local application of heat
- Incision and drainage
- Systemic antibiotics (see “Empiric antibiotic therapy for skin and soft tissue infections”)
Otomycosis (fungal otitis externa) 
- Aspergillus spp. (most common)
- Candida spp.
- Immunosuppression (e.g., HIV, diabetes)
- Long-term antibiotic therapy
- Residence in a hot, humid area
- Largely a clinical diagnosis; in addition to classic clinical features of OE, patients may additionally have:
- Thick debris in the ear canal
- Visible hyphae 
- Insufficient response to antimicrobial therapy
- Fungal culture is recommended. 
- Debridement and cleaning
Antifungal therapy 
- Usually topical, e.g., clotrimazole
- Occasionally, systemic (e.g., itraconazole) or combined therapy is required.
General principles 
Diagnosis is clinical; AOE is likely if all of the following are present : 
- 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:
- In suspected comorbid disease
- To rule out differential diagnoses of otitis externa
- For refractory disease or suspected subtypes, e.g., MOE
Diagnostic studies 
Pneumatic otoscopy and/or tympanometry
- Perform if there is diagnostic uncertainty between AOE and acute otitis media.
- Both studies are normal in AOE. 
Screening for comorbidities: Consider based on clinical features.
- AOE: screening for diabetes or screening for HIV
- COE: screening for autoimmune disease 
Culture of ear secretions should be obtained if there is: 
- Insufficient response to initial treatment
- ≥ 1 risk factor for a fungal or antibiotic-resistant pathogen
- Concern the infection has extended (i.e., beyond the EAC)
- Patients with clinical features of MOE: see “Diagnostics of MOE”.
|Differential diagnosis of otitis externa |
|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 and otomycosis see “Subtypes and Variants”; treatment of MOE is covered in a separate article. COE is treated according to its etiology, e.g., fungal, allergic, or autoimmune. 
- Initiate supportive therapy as needed, e.g., analgesia, ear wick, aural toilet.
- Evaluate for indications for systemic antibiotic therapy in AOE and start if present.
- For uncomplicated AOE, initiate topical therapy for OE. 
- Antibiotic (ofloxacin, ciprofloxacin, or gentamicin); or antiseptic ear drops
- Preparations may be combined with glucocorticoids.
- Reassess at 48–72 hours; if there is no improvement, consider: 
- Differential diagnoses of OE or MOE
- Incorrect use or impaired delivery of ear drops
- Allergic contact dermatitis from an ototopical agent (commonly neomycin)
- Consider a referral to otolaryngology in severe or refractory AOE.
If patients do not respond to initial topical therapy, consider alternative diagnoses such as allergic contact dermatitis from an ototopical agent, otomycosis, or MOE. 
Supportive therapy 
- Start scheduled oral analgesia. 
- First-line: ibuprofen or acetaminophen 
- Second-line: short course combination opioids, e.g., hydrocodone/ibuprofen or oxycodone/acetaminophen 
- For further information including dosages, see “Pain management.”
- Advise patients:
- How to administer ear drops correctly 
- To avoid water exposure during treatment 
- To disinfect in-ear devices and avoid wearing them until pain and/or discharge has improved 
- On prevention of OE
- Consider performing aural toilet or placing an ear wick to facilitate better topical treatment.
- Perform aural toilet if there is significant debris in the EAC, unless: 
- Risk factors for MOE are present.
- The tympanic membrane is perforated.
- Insert an ear wick if there is significant edema of the EAC or visualization of the TM is not possible. 
- Perform aural toilet if there is significant debris in the EAC, unless: 
Aural toilet can be painful for patients with severe inflammation; give analgesia beforehand and consider procedural sedation. 
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). 
Systemic antibiotics for OE 
- Topical antimicrobial administration is not possible.
- Disease extension outside the ear canal, e.g.:
- Cellulitis of the neck or face
- Suspected MOE
- Concomitant AOM
- Uncontrolled diabetes
- Previous local radiotherapy
- Choice of agent: should cover P. aeruginosa and S. aureus, e.g., ciprofloxacin 
Topical antimicrobials for OE 
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 
- 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 |
If allergic contact dermatitis secondary to ototopical agents (e.g., neomycin) is suspected, discontinue the agent and treat with a topical glucocorticoid. 
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. 
- Recurrent episodes of OE
- Chronic dermatological conditions (e.g., atopic dermatitis, psoriasis)
- Frequent participation in water sports
- 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. 
- 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.