Abstract: We identified three studies as eligible for inclusion in the review. Two were in the previous review and one new study was included. We considered the older studies to be at high or unclear risk of bias whereas we judged the newly included study at low risk of bias. The studies varied in treatment duration (from 7 to 14 days) and the antibiotic used (two studies used amoxicillin/clavulanate acid and one used erythromycin). We included 190 children (171 completed), mean ages ranged from 21 months to six years, in the meta-analyses. Analysis of all three trials (190 children) found that treatment with antibiotics reduced the proportion of children not cured at follow-up (primary outcome measure) (odds ratio (OR) 0.15, 95% confidence interval (CI) 0.07 to 0.31, using intention-to -treat analysis), which translated to a number needed to treat for an additional beneficial outcome (NNTB) of 3 (95% CI 2 to 4). We identified no significant heterogeneity (for both fixed-effect and random-effects model the I² statistic was 0%). Two older trials assessed progression of illness, defined by requirement for further antibiotics (125 children), which was significantly lower in the antibiotic group (OR 0.10, 95% CI 0.03 to 0.34; NNTB 4, 95% CI 3 to 5). All three trials (190 children) reported adverse events, which were not significantly increased in the antibiotic group compared to the control group (OR 1.88, 95% CI 0.62 to 5.69). We assessed the quality of evidence GRADE rating as moderate for all outcome measures, except adverse events which we assessed as low quality. Evidence suggests antibiotics are efficacious for the treatment of children with chronic wet cough (greater than four weeks) with an NNTB of three. However, antibiotics have adverse effects and this review reported only uncertainty as to the risk of increased adverse effects when they were used in this setting. The inclusion of a more robust study strengthened the previous Cochrane review and its results.

Plain-language summary: We included randomised controlled trials that compared antibiotics with a placebo (pretend treatment) or control group. The children included in the trials had wet cough lasting more than 10 days. The evidence is current to September 2017. We found three studies that varied in a number of ways including different antibiotics (two studies used amoxicillin/clavulanate acid and one used erythromycin) and length of treatment was seven or 14 days. The mean ages of the children ranged from 21 months to six years. This review, involving 190 children with persistent wet cough, found that antibiotics were beneficial in curing the cough. The cure rate was one child cured for every three children treated. Antibiotics also prevented the illness from getting worse, thus avoiding a further course of antibiotics, for one in every four children treated. We found no clear evidence about whether antibiotics were associated with more side effects. We could not assess long-term results. The reliability of the evidence was moderate when using antibiotics to cure cough and for illness progression, while it was only low for side effects of medicines. Antibiotics are effective in treating children with chronic (greater than four weeks) wet cough and could be considered when they present to doctors.