Acute asthma is responsible for many emergency department visits annually. Between 12-16% will relapse to require additional interventions within two weeks of ED discharge. Treatment of acute asthma is based on rapid reversal of bronchospasm and reducing airway inflammation and this review examines the evidence for using systemic corticosteroids to improve outcomes after discharge from the ED. The authors determined the benefit of corticosteroids (oral, intramuscular, or intravenous) for the treatment of asthmatic patients discharged from an acute care setting (i.e. usually the emergency department) after assessment and treatment of an acute asthmatic exacerbation. The Cochrane Airways Group "Asthma and Wheez* RCT" register was searched using the terms: a) Asthma OR Wheez* b) Glucocorticoid OR Steroid* AND c) Exacerbat* OR Relapse* OR Emerg*. In addition, authors of all included studies were contacted to determine if unpublished studies which met the inclusion criteria were available. Bibliographies from included studies, known reviews and texts were also searched for additional citations. Only randomized controlled trials were eligible for selection. Studies were included in this review if they dealt with the outpatient treatment of asthmatic exacerbations using glucocorticoids at discharge and reported either relapse rate or PFTs. Two independent reviewers first identified potentially relevant studies and then selected articles for inclusion. Methodological quality was assessed independently by two reviewers. Agreement was assessed using kappa (k) statistics. Data were extracted independently by two reviewers; authors were contacted to verify the extracted data and clarify missing information. When author contact was unsuccessful, missing data were estimated from graphs where possible. Sensitivity, sub-group and overall analyses were performed using the Cochrane Review Manager. A search that yielded 229 references identified 169 (73%) original publications. Reviewers identified 8 studies for potential inclusion (k =0.76); 18 references were added by searching publication reference lists and contact with authors. Of these 26 articles, a total of 7 were included in the overview. Two studies used intramuscular corticosteroids, five studies used oral corticosteroids. Significantly fewer patients in the corticosteroid group relapsed to receive additional care in the first week (odds ratio (OR) 0.35; 95% confidence interval (CI): 0.17, 0.73). This favorable effect was maintained over the first 21 days (OR 0.33; 95% CI: 0.13, 0.82). Patients receiving corticosteroids had less need for beta-agonists (weighted mean difference (WMD) -3.3 activations/day; 95% CI: -5.5, -1.0). Changes in pulmonary function tests (SMD 0.045; 95% CI: -0.47, 0.56) and side effects (SMD 0.03; 95% CI : -0.38, 0.44) in the first 7-10 days, while rarely reported, showed no differences between the treatment groups. Statistically significant heterogeneity was identified for the side effect results; all other outcomes were homogeneous. It appears that IM corticosteroids are similarly efficacious to a 7-10 day tapering course of oral agents. From these results, as few as 13 patients need to be treated to prevent relapse to additional care after an exacerbation of asthma. The authors conclude that a short course of corticosteroids following assessment for an acute exacerbation of asthma significantly reduces the number of relapses to additional care and decreases beta-agonist use without an apparent increase in side effects. Intramuscular corticosteroids appear as effective as oral agents.