The quality of evidence is downgraded by study limitations (lack of/unclear allocation concealment and blinding), by inconsistency (variability in results), and by imprecise results (few patients and wide confidence intervals).
A Cochrane review [Abstract] 1 included 6 studies with a total of 497 children to study efficacy. They showed some benefit (e.g. reduction of cough at day 7) from mucolytic agents, although differences were of little clinical relevance. Data for infants younger than 2 years were unavailable. Thirty-four studies including the previous 6 trials were eligible to study safety (n=2064). Overall safety was good but very few data were available to evaluate safety in infants younger than 2 years. However, 59 cases of paradoxically increased bronchorrhoea observed in infants were reported to the French pharmacovigilance system 2.
Regarding children younger than 2 years old, there are strong concerns about the safety of acetylcysteine and carbocysteine (increased instead of decreased bronchial secretions). These concerns led to the withdrawal of their licence in this age group in France and Italy in 2010. Therefore, these drugs should only be used for acute respiratory tract infections in neonates and infants in the context of a randomised controlled trial.
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