Level 2: Mid-level evidence
A systematic review of seven randomized placebo-controlled trials evaluated the efficacy of a single dose of parenteral dexamethasone (in addition to standard abortive therapy) in 738 patients seen in an emergency department for acute severe migraine (BMJ. 2008;336:1359-1361; full-text available online free of charge at: www.bmj.com/cgi/content/full/336/7657/1359, accessed August 13, 2008). The review lacked a complete quality assessment, and only one of the seven trials independently found a statistically significant effect. Dexamethasone was associated with a reduction in headache recurrence within 72 hours in a meta-analysis (P=.003, NNT 9, 95% CI 6-25) but did not relieve migraine pain. Dexamethasone was also associated with a trend toward decreased nausea but increased dizziness.