Efficacy of ketamine in the treatment of migraines and other unspecified primary headache disorders compared to placebo and other interventions: a systematic review.

Further double-blind controlled studies are needed to assess the efficacy of ketamine in treating acute and chronic refractory migraines and other primary headaches using intranasal and subcutaneous routes. These studies should include a long-term follow-up and different ketamine dosages in diagnosed patients following international standards for diagnosing headache/migraine.