A Cochrane review [Abstract] 1 included 29 studies (19 in adults, 10 in children) with a total of 4 835 people (3 799 adults and 1 036 children). Twenty-one studies reported adverse effects. There was a wide range across studies, with higher numbers of adverse effects in participants taking preparations containing antihistamines and dextromethorphan.
Results of studies in adults:
Results of studies in children:
Another Cochrane review [Abstract] 1 focusing on OTC cough medications as an adjunct to antibiotics in children and adults with pneumonia included 4 studies with a total of 224 subjects (exclusively children in one study, adolescents or adults in 3 studies). Only 2 studies comparing mucolytics with placebo had extractable pneumonia-specific data. They demonstrated no significant difference for the primary outcome of 'not cured or not improved' for mucolytics. A secondary outcome of 'not cured' was reduced (OR 0.36, 95% CI 0.16 to 0.77; NNT 5, 95% CI 3 to 16 for children and OR 0.32, 95% CI 0.13 to 0.75; NNT 5, 95% CI 3 to 19 for adults). In a post hoc analysis combining data for children and adults, again there was no difference in the primary outcome of 'not cured or not improved' (OR 0.85, 95% CI 0.40 to 1.80) although mucolytics reduced the secondary outcome 'not cured' (OR 0.33, 95% CI 0.19 to 0.60; NNT 4, 95% CI 3 to 8).
Comment: The quality of evidence is downgraded by limitations in study quality (inadequate or unclear randomization method and allocation concealment), by inconsistency (variability in results across studies, heterogeneity in interventions and outcomes), by indirectness (differences in studied patients), and by imprecise results (limited study size for each comparison).
Primary/Secondary Keywords