Otitis externa is thought to affect 10% of people at some stage, and can present in acute, chronic, or necrotising forms. Otitis externa may be associated with eczema of the ear canal, and is more common in swimmers, humid environments, people with absence of ear wax or with narrow ear canals, hearing-aid users, and after mechanical trauma.We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of empirical and prophylactic treatments for otitis externa? We searched: Medline, Embase, The Cochrane Library, and other important databases up to October 2007 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).We found nine systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.In this systematic review, we present information relating to the effectiveness and safety of the following interventions: oral antibiotics, specialist aural toilet, topical acetic acid drops or spray, topical aluminium acetate drops, topical antibacterials, topical antifungals, topical anti-infective agents, topical corticosteroids, and water exclusion.