• Assess presence of precipitating and risk factors, severity of symptoms and inflammation, and patency of tympanic membrane as for acute otitis externa. In addition assess for:
• Severity of itching — usually the most prominent symptom — and signs of scratching.
• Signs of fungal infection on examining the ear canal — whitish cotton-like strands of Candida, small black or white balls of Aspergillus.
• Signs of generalized dermatitis — mild erythema and lichenification (thickening of the skin) in the ear canal, and signs of underlying disease elsewhere (e.g. seborrhoeic dermatitis, psoriasis).
• Evidence of contact allergy or sensitivity — use of ear plugs, hearing aid, earrings, sensitizing medications (topical and systemic).
• Evidence of a source for an id (auto eczematization) reaction — a focus of fungal infection elsewhere in the body (e.g. skin, nails, vagina) can cause a secondary inflammatory process in the external ear canal.

In depth

• Laboratory investigations are rarely useful. However, if the treatment strategy fails, consider taking an ear swab for bacterial and fungal microscopy and culture.

In depth

• Apply general measures to keep the ear canal dry and free of debris and discharge while avoiding injuring it; relieve itch and pain; remove any precipitating antigens or irritants; treat any underlying skin condition such as seborrhoeic dermatitis. See Initial management for acute diffuse otitis externa.
• Treatment may be difficult, and may require trials of more than one strategy.
• If fungal infection is suspected (signs of fungal growth in ear canal) — prescribe a topical antifungal preparation and seek specialist advice if there is inadequate response.
• If the cause seems to be seborrhoeic dermatitis — treat topically with an antifungal–corticosteroid combination.
• If no cause is evident:
• Prescribe a 7-day course of a topical preparation containing only a corticosteroid without antibiotic. Consider co-prescribing an acetic acid spray.
• If there is an adequate response:
• The corticosteroid treatment may need to be continued. Reduce the potency of the corticosteroid and/or the frequency of application to the minimum required to maintain control.
• If treatment cannot be withdrawn after 2 or 3 months, seek specialist advice.
• If the response is inadequate, consider a trial of a topical antifungal preparation.

In depth

• If otitis externa does not respond to appropriate treatment in primary care.
• If contact sensitivity is suspected and patch testing would be useful to guide further management.
• If the ear canal is occluded or becoming occluded.
• If malignant otitis is suspected.

In depth

• Review response after completion of a course of treatment.
• People with diabetes or compromised immunity are at increased risk for complications and should be followed up more closely.

In depth