BACKGROUND: Chronic suppurative otitis media (CSOM), sometimes referred to as chronic otitis media, is a chronic inflammation and often polymicrobial infection of the middle ear and mastoid cavity, characterised by ear discharge (otorrhoea) through a perforated tympanic membrane. The predominant symptoms of CSOM are ear discharge and hearing loss. Antibiotics are the most common treatment for CSOM, and aim to kill or inhibit the growth of micro-organisms that may be responsible for the infection. Antibiotics can be administered both topically and systemically, and can be used alone or in addition to other treatments for CSOM, such as ear cleaning (aural toileting). This is the first update of a review published in 2021. The update found no new studies. It is one of a suite of seven Cochrane reviews evaluating the effects of non-surgical interventions for CSOM. OBJECTIVES: To assess the benefits and harms of topical versus systemic antibiotics for people with CSOM. SEARCH METHODS: We searched the Cochrane ENT Register, CENTRAL, Ovid MEDLINE, Ovid Embase, and five other databases. We also searched ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform (ICTRP). The latest search date was 15 June 2022. SELECTION CRITERIA: We included randomised controlled trials (RCTs) with at least a one-week follow-up involving adults and children who had chronic ear discharge of unknown cause or CSOM, where the ear discharge had continued for more than two weeks. The studies compared topical antibiotics versus systemic (oral, injection) antibiotics. The two main comparisons were the same type of antibiotic in both treatment groups and different types of antibiotics in each group. Within each comparison, we separated studies into 1. those in which both groups of participants had received aural toileting in addition to the antibiotics, and those where neither group had received aural toileting, and 2. those in which both groups received some other concomitant treatment (such as topical antiseptics) and those with no such concomitant treatment. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methodological procedures. Our primary outcomes were: resolution of ear discharge or 'dry ear' (whether otoscopically confirmed or not, measured at between one week and up to two weeks, two weeks up to four weeks, and after four weeks), health-related quality of life using a validated instrument, and ear pain (otalgia) or discomfort or local irritation. Secondary outcomes were hearing, serious complications, and ototoxicity. We used GRADE to assess the certainty of the evidence for each outcome. MAIN RESULTS: This update did not find any new studies. We included six studies (445 participants), all with high risk of bias. Three studies included participants with confirmed CSOM, where perforation of the ear drum was clearly documented. None of the studies reported results for resolution of ear discharge after four weeks or health-related quality of life. 1. Topical quinolone versus systemic quinolone Four studies (325 participants) compared topical versus systemic (oral) administration of ciprofloxacin. Topical administration may slightly increase resolution of ear discharge at one to less than two weeks (risk ratio (RR) 1.50, 95% confidence interval (CI) 1.22 to 1.84; 2 studies, 210 participants; low-certainty evidence). These studies either did not mention aural toileting or limited it to the first visit. Three studies (265 participants) reported that they did not suspect ototoxicity in any participants, but it is unclear how this was measured (very low-certainty evidence). No studies reported the outcomes of resolution after four weeks, health-related quality of life, ear pain, or serious complications. No studies reported results for hearing, despite it being measured in three studies. 2. Topical quinolone versus systemic aminoglycosides One study (60 participants) compared topical ciprofloxacin versus gentamicin injected intramuscularly. No aural toileting was reported. Resolution of ear discharge was not measured at one to two weeks. The study did not report any "side effects" from which we assumed that no ear pain, suspected ototoxicity, or serious complications occurred (very low-certainty evidence). The study stated that "no worsening of the audiometric function related to local or parenteral therapy was observed." 3. Topical quinolone versus systemic penicillin plus beta-lactamase inhibitor One study (60 participants) compared topical ofloxacin versus oral amoxicillin-clavulanic acid with all participants receiving suction ear cleaning at the first visit. Oral amoxicillin-clavulanic acid may increase the resolution of ear discharge at one to less than two weeks compared to topical ofloxacin, but the evidence is very uncertain. The evidence is also very uncertain about the effects of topical ofloxacin compared with oral amoxicillin-clavulanic acid on ear pain, hearing, or suspected ototoxicity (all very low-certainty evidence). No studies reported the outcomes of resolution after four weeks, health-related quality of life, and serious complications. AUTHORS' CONCLUSIONS: There was a limited amount of low- or very low-quality evidence available, from studies completed over 15 years ago, to determine whether topical or systemic antibiotics are more effective in achieving resolution of ear discharge for people with CSOM. This was mostly due to high risk of bias in the studies and imprecision. However, amongst this uncertainty, there is some evidence to suggest that the topical administration of quinolone antibiotics may be slightly more effective than systemic administration of antibiotics in achieving resolution of ear discharge (dry ear). There is limited evidence available regarding different types of topical antibiotics. It is not possible to determine with any certainty whether topical quinolones are better or worse than systemic aminoglycosides. These two groups of compounds have different adverse effect profiles, but there is insufficient evidence from the included studies to make any comment about these. In general, harmful effects were poorly reported. Limitations of the review include lack of recency in data, and limited information on certain population groups or interventions.