C12. Analysis: The data will be analyzed in an "intention-to-treat" manner. Once a patient is randomized and receives the dexamethasone, their pain scores will be included in the 24-hour analysis regardless of whether or not they received rescue medication or completed the protocol. However, lost-to-follow-up subjects will be excluded from the primary analysis (a sensitivity analysis will be conducted in which lost-to-follow-up subjects are assumed to have a poor outcome). Study enrollment will continue until the pre-determined number of subjects have completed the primary endpoint. Chi-square analysis will be used to compare rates. Students t-tests will be used to compare mean differences in pain scores. Multivariate regression models will be used to analyze the influence of the co-variates discussed above, particularly allodynia, duration of headache, and use of medication prior to ED presentation. Briefly, evidence of confounding will be sought by looking for an association between the heterogeneous variable and both the independent (study medication) and dependent (pain status) variables. Between-group differences will be expressed as means or proportions, bounded by 95% confidence intervals (95% CI).