Azithromycin for acute bronchitis: a randomised, double-blind, controlled trial

Background The value of azithromycin for treatment of acute bronchitis is unknown, even though this drug is commonly prescribed. We have investigated this question in a randomised, double-blind, controlled trial. Methods Adults diagnosed with acute bronchitis, without evidence of underlying lung disease, were randomly assigned azithromycin (n=112) or vitamin C (n=108) for 5 days (total dose for each 1•5 g). All individuals were also given liquid dextromethorphan and albuterol inhaler with a spacer. The primary outcome was improvement in health-related quality of life at 7 days; an important difference was defined as 0•5 or greater. Analysis was by intention to treat. Findings The study was stopped by the data-monitoring and safety committee when 220 patients had been recruited. On day 7, the adjusted difference in health-related quality of life was small and not significant (difference 0•03 [95% CI -0•20 to 0•26], p=0•8). 86 (89%) of 97 patients in the azithromycin group and 82 (89%) of 92 in the vitamin C group had returned to their usual activities by day 7 (difference 0•5% [−10% to 9%], p>0•9). There were no differences in the frequency of adverse effects; three patients in the vitamin C group discontinued the study medicine because of perceived adverse effects, compared with none in the azithromycin group. Most patients (81%) reported benefit from the albuterol inhaler. Interpretation Azithromycin is no better than low-dose vitamin C for acute bronchitis. Further studies are needed to identify the best treatment for this disorder.