Patients with chronic obstructive pulmonary disease (COPD) are prone to acute respiratory exacerbations, which can develop suddenly or subacutely over the course of several days. Exacerbations have a detrimental effect on patients' health status and increase the burden on the healthcare system. Initial treatment is unsuccessful in 24-27% of patients, who have a relapse or a second exacerbation within 30 days of the initial event. No obvious benefit has been seen in recent clinical trials of anti-tumour necrosis factor therapy, anti-leukotriene therapy, intensive chest physiotherapy, or early inpatient pulmonary rehabilitation for treatment of exacerbations. By contrast, clinical trials of prevention rather than acute treatment have shown promising results. Long acting β agonist (LABA) or long acting anti-muscarinic (LAMA) bronchodilators and inhaled corticosteroid-LABA combinations prevent exacerbations in patients at risk, with relative risk reductions averaging 14-27% for each of these drugs relative to placebo. Triple therapy with inhaled corticosteroid-LABA plus LAMA may provide additional benefit, although study results to date are heterogeneous and more studies are needed. Pneumonia is an important complication of treatment with inhaled corticosteroid-LABA products, and the risk of pneumonia seems to be doubled in patients with COPD who use fluticasone. The addition of azithromycin to usual COPD therapy prevents exacerbations, although it may prolong the Q-T interval and increase the risk of death from cardiovascular disease in patients prone to arrhythmia. New potential drugs--including mitogen activated protein kinase inhibitors, phosphodiesterase 3 inhibitors, and monoclonal antibodies to the interleukin 1 receptor--offer additional hope for treatments that may prevent exacerbations in the future.