BACKGROUND: There are no clearly effective treatments for the cough of acute bronchitis. Beta2-agonists are often prescribed, perhaps because clinicians suspect many patients also have reversible airflow restriction contributing to the symptoms.
OBJECTIVES: To determine whether beta2-agonists improve acute bronchitis symptoms in patients with no underlying pulmonary disease.
SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) 2011, issue 1 which contains the Acute Respiratory Infections Group's Specialised Register, MEDLINE (January 1966 to February week 1, 2011) and EMBASE (1974 to February 2011).
SELECTION CRITERIA: Randomised controlled trials (RCTs) in which patients (adults, or children over two years of age) with acute bronchitis or acute cough and without known pulmonary disease were allocated to beta2-agonist versus placebo, no treatment or alternative treatment.
DATA COLLECTION AND ANALYSIS: Three review authors independently selected outcomes and extracted data while blinded to study results. Two review authors independently assessed each trial for risk of bias. We analysed trials in children and adults separately.
MAIN RESULTS: Two trials in children (n = 109) with no evidence of airway obstruction did not find any benefits from oral beta2-agonists. Five trials in adults (n = 418) had mixed results but overall summary statistics did not reveal any significant benefits from oral (three trials) nor inhaled (two trials) beta2-agonists. There were no significant differences in daily cough scores nor in the percentage of adults still coughing after seven days (control group 73%; risk ratio (RR) 0.77, 95% confidence interval (CI) 0.54 to 1.09). in one trial, subgroups with evidence of airflow limitation had lower symptom scores if given beta2-agonists. The trials that noted quicker resolution of cough with beta2-agonists were those with a higher proportion of wheezing patients at baseline. Adults given beta2-agonists were more likely to report tremor, shakiness or nervousness (RR 7.94, 95% CI 1.17 to 53.94; number needed to treat to harm (NNTH) 2.3).
AUTHORS' CONCLUSIONS: There is no evidence to support the use of beta2-agonists in children with acute cough who do not have evidence of airflow obstruction. There is also little evidence that the routine use of beta2-agonists is helpful for adults with acute cough. These agents may reduce symptoms, including cough, in people with evidence of airflow obstruction. However, this potential benefit is not well-supported by the available data and must be weighed against the adverse effects associated with their use.