C10c. Pre-Medication: In previous work, although 25% of the investigators' population took no analgesic medication prior to presentation to the ED, this co-variate did not confound the association between study medication and persistent pain-free [30]. Nevertheless, the investigators will record all migraine-relevant medications used by their subjects prior to ED presentation, group these by class, and determine if this co-variate has a relationship with the primary outcomes.