Abstract: We identified a total of 556 records, of which 486 records were excluded on the basis of title and abstract. We retrieved the remaining 70 references in full to determine eligibility. No studies fulfilled the inclusion criteria of this review, and thus we found no evidence to support or oppose the use of codeine or derivatives as antitussive agents for chronic cough in children. While chronic cough is not the same as acute cough, systematic reviews on the use of codeine efficacy for acute cough in children conclude an overall lack of evidence to support or oppose the use of over-the-counter cough and cold medications containing codeine (or derivatives) for treatment of acute cough in children. The lack of sufficient evidence to support the use of these medications has been consistently reaffirmed by medical experts in international chronic cough guidelines and by governing medical and pharmaceutical authorities in the USA, Europe, Canada, New Zealand, and Australia. Due to the lack of sufficient evidence to support efficacy, and the known risks associated with use - in particular the increased risks for children - these medications are now not recommended for children less than 12 years of age and children between 12 to 18 years with respiratory conditions. This review has highlighted the absence of any randomised controlled trials evaluating codeine-based medications in the treatment of childhood chronic cough. Given the potential adverse events of respiratory suppression and opioid toxicity, national therapeutic regulatory authorities recommend the contraindication of access to codeine in children less than 12 years of age. We suggest that clinical practice adhere to clinical practice guidelines and thus refrain from using codeine or its derivatives to treat cough in children. Aetiological-based management practices continue to be advocated for children with chronic cough.

Plain-language summary: We searched for any randomised controlled trial comparing either codeine (or medications produced from codeine) versus placebo in the treatment of chronic cough (4 weeks or longer) in children aged 18 years and younger. The search identified 556 records. We reviewed and assessed all of these against predetermined inclusion/exclusion criteria. We found no eligible studies to include in this review. However, our search did find studies that investigated codeine (or medications produced from codeine) in the treatment of acute cough (two weeks or less) in children. Another Cochrane review specifically for children with acute cough evaluated these studies and found no evidence to support or oppose use of codeine (or medications produced from codeine). This overall lack of evidence is consistent with international chronic cough guidelines, which recommend treating the cause of the cough. Due to the known risks associated with use, in particular the increased risks for children, governing bodies in the USA, Europe, Canada, New Zealand, and Australia have stated these medications are now not recommended for children younger than 12 years of age and children between 12 to 18 years with respiratory conditions. Given the lack of supporting trials, the findings from trials of acute cough in children, and the known harmful side effects, we have concluded that codeine-based medications cannot be recommended in children with chronic cough. We found no studies and hence there is no quality of evidence.