Status migrainosus (SM) is a subtype of migraine defined by migraine lasting >72 hours and is difficult to treat in clinical practice. Magnesium is commonly used in the treatment of migraine. We conducted a retrospective cohort study to determine if length of admission was associated with IV magnesium therapy in patients with SM. We reviewed the charts of all patients admitted to a large military treatment facility from October 2013 to December 2018 with the admission diagnosis of migraine. There were 333 patients that were reviewed and 141 met the inclusion criteria. Nearly half of patients received IV magnesium therapy with routine care (46.8%, n = 66). IV magnesium therapy was not associated with length of admission (58 hours (IQR 25.5, 86) compared to 42 hours (IQR 25.5, 80.5) respectively, p = 0.47). Of the cases without Neurology consultation, patients who received magnesium therapy (n = 5) had numerically shorter admission but this difference did not meet statistical significance (n = 12) (17 hours (IQR 13.75, 31.25) versus 24.5 hours (IQR 15.25, 58.75), p = 0.0534). This study contributes to the limited pool of available data on the treatment of SM. Prospective research is needed to study magnesium therapy in patients with prolonged migraine.