October 2004: During the review process the selection criteria was changed from RCTs comparing antibiotics to placebo medication to also include studies comparing antibiotics with a 'no treatment' control group. This was done because there were an insufficient number of placebo‐controlled trials to be sure that the information obtained from unblinded studies would not be clinically useful. The inclusion criteria were changed to allow studies of children who had prolonged moist cough for >10 days. We planned to assess the impact of antibiotics on children with prolonged moist cough >3 weeks (our preferred definition of chronic cough) as an a priori subgroup analysis. We also decided to include studies that were not exclusively limited to children with "moist sounding" cough if subgroup data were not available and >50% of children had a moist cough or other clinical features consistent with diagnosis (e.g. sputum production, excess secretions etc). The review uses a summary weighted odds ratio rather than relative risk as was stated in the protocol. This decision was made as it appeared the most clinically relevant analysis method particularly when converted to number needed to treat.