A meta-analysis of 21 double-blinded randomized control trials shows that a short-course of antibiotics (< or = 5 days) used in standard treatment for acute exacerbations of chronic bronchitis and COPD is just as effective as longer treatment courses (> 5 days).

Source: El Moussaoui R, Roede BM, Speelman P, et al. Short-course antibiotic treatment in acute exacerbations of chronic bronchitis and COPD: a meta-analysis of double-blind studies. Thorax 2008;63:415-22.