Headache is the fifth most common presenting chief complaint in emergency departments, and it is vital to quickly rule out life-threatening secondary causes. Though there are many medications, new and old, that can be used to treat primary headache, the evidence for their effectiveness can be conflicting. This review describes the pathology, workup, and treatment for migraine and other primary headaches based on the best available evidence, including novel medications, nerve blocks, and strategies for preventing postdrome recurrence. Other headache disorders, including cluster headache, medication overuse headache, and chronic migraine are also reviewed.