Acute otitis media (AOM) is one of the most common diseases in childhood for which antibiotics are commonly prescribed; a systematic review reported a pooled prevalence of 85.6% in high-income countries. This is an update of a Cochrane Review first published in the Cochrane Library in 1997 and updated in 1999, 2005, 2009, 2013 and 2015.To assess the effects of antibiotics for children with AOM.We searched CENTRAL, MEDLINE, Embase, Current Contents, CINAHL, LILACS and two trial registers. The date of the search was 14 February 2023.We included randomised controlled trials comparing 1) antimicrobial drugs with placebo, and 2) immediate antibiotic treatment with expectant observation (including delayed antibiotic prescribing) in children with AOM.Two review authors independently screened trials for inclusion and extracted data using the standard methodological procedures recommended by Cochrane. Our primary outcomes were: 1) pain at various time points (24 hours, two to three days, four to seven days, 10 to 14 days), and 2) adverse effects likely to be related to the use of antibiotics. Secondary outcomes were: 1) abnormal tympanometry findings, 2) tympanic membrane perforation, 3) contralateral otitis (in unilateral cases), 4) AOM recurrences, 5) serious complications related to AOM and 6) long-term effects (including the number of parent-reported AOM symptom episodes, antibiotic prescriptions and health care utilisation as assessed at least one year after randomisation). We used the GRADE approach to rate the overall certainty of evidence for each outcome of interest.Antibiotics versus placebo We included 13 trials (3401 children and 3938 AOM episodes) from high-income countries, which we assessed at generally low risk of bias. Antibiotics do not reduce pain at 24 hours (risk ratio (RR) 0.89, 95% confidence interval (CI) 0.78 to 1.01; 5 trials, 1394 children; high-certainty evidence), or at four to seven days (RR 0.76, 95% CI 0.50 to 1.14; 7 trials, 1264 children), but result in almost a third fewer children having pain at two to three days (RR 0.71, 95% CI 0.58 to 0.88; number needed to treat for an additional beneficial outcome (NNTB) 20; 7 trials, 2320 children; high-certainty evidence), and likely result in two-thirds fewer having pain at 10 to 12 days (RR 0.33, 95% CI 0.17 to 0.66; NNTB 7; 1 trial, 278 children; moderate-certainty evidence). Antibiotics increase the risk of adverse events such as vomiting, diarrhoea or rash (RR 1.38, 95% CI 1.16 to 1.63; number needed to treat for an additional harmful outcome (NNTH) 14; 8 trials, 2107 children; high-certainty evidence). Antibiotics reduce the risk of children having abnormal tympanometry findings at two to four weeks (RR 0.83, 95% CI 0.72 to 0.96; NNTB 11; 7 trials, 2138 children), slightly reduce the risk of experiencing tympanic membrane perforations (RR 0.43, 95% CI 0.21 to 0.89; NNTB 33; 5 trials, 1075 children) and halve the risk of contralateral otitis episodes (RR 0.49, 95% CI 0.25 to 0.95; NNTB 11; 4 trials, 906 children). However, antibiotics do not reduce the risk of abnormal tympanometry findings at six to eight weeks (RR 0.89, 95% CI 0.70 to 1.13; 3 trials, 953 children) and at three months (RR 0.94, 95% CI 0.66 to 1.34; 3 trials, 809 children) or late AOM recurrences (RR 0.94, 95% CI 0.79 to 1.11; 6 trials, 2200 children). Severe complications were rare, and the evidence suggests that serious complications do not differ between children treated with either antibiotics or placebo. Immediate antibiotics versus expectant observation We included six trials (1556 children) from high-income countries. The evidence suggests that immediate antibiotics may result in a reduction of pain at two to three days (RR 0.53, 95% CI 0.35 to 0.79; NNTB 8; 1 trial, 396 children; low-certainty evidence), but probably do not reduce the risk of pain at three to seven days (RR 0.75, 95% CI 0.50 to 1.12; 4 trials, 959 children; moderate-certainty evidence), and may not reduce the risk of pain at 11 to 14 days (RR 0.91, 95% CI 0.75 to 1.10; 1 trial, 247 children; low-certainty evidence). Immediate antibiotics increase the risk of vomiting, diarrhoea or rash (RR 1.87, 95% CI 1.39 to 2.51; NNTH 10; 3 trials, 946 children; high-certainty evidence). Immediate antibiotics probably do not reduce the proportion of children with abnormal tympanometry findings at four weeks and evidence suggests that immediate antibiotics may not reduce the risk of tympanic membrane perforation and AOM recurrences. No serious complications occurred in either group.This review reveals that antibiotics probably have no effect on pain at 24 hours, a slight effect on pain in the days following and only a modest effect on the number of children with tympanic perforations, contralateral otitis episodes and abnormal tympanometry findings at two to four weeks compared with placebo in children with AOM. In high-income countries, most cases of AOM spontaneously remit without complications. The benefits of antibiotics must be weighed against the possible harms: for every 14 children treated with antibiotics, one child experienced an adverse event (such as vomiting, diarrhoea or rash) that would not have occurred if antibiotics were withheld. For most children with mild disease in high-income countries, an expectant observational approach seems justified. Therefore, clinical management should emphasise advice about adequate analgesia and the limited role for antibiotics.