This research study will be a prospective, randomized, double-blind, placebo-controlled trial. Because ketamine has yet to be directly studied as treatment for acute migraine headache in the emergency department, the research team is initially interested if ketamine can reduce pain scores in headache patients and reduce the incidence of recurrence while exhibiting an adequate safety profile. By using a placebo-controlled study design, the research team can adequately investigate the effectiveness of the medication in a subgroup previously not well studied.