Asthma is a chronic inflammatory disease, which is characterised by reversible airflow obstruction in response to a variety of stimuli. Exacerbations in response to airway irritants are part of the natural history of asthma, but often they also represent a failure in chronic treatment. Presentations to emergency departments and other acute care settings are common and frequently lead to hospitalisation and other complications. After treatment, however, most patients are discharged to the care of their primary care physician for further management. This review highlights the role of systemic and inhaled corticosteroids as mainstays of treatment in the acute and sub-acute phase of an exacerbation. These agents form the basis of most current clinical practice guidelines, yet their use is not universal. We will review the evidence for the use of these agents that arises from the Cochrane Collaboration of Systematic Reviews contained in the Cochrane Library.