Migraine.

Migraine, a common primary headache disorder, ranks second only to low back pain as a leading cause of disability. Proposed mechanisms include vasodilation, trigeminovascular activation, and neurogenic inflammation. Diagnosis is clinical, as no biomarker exists, and the International Classification of Headache Disorders-3 has clinical criteria for diagnosis. Differentiating migraine from other conditions can be challenging, with "red" and "green flags" guiding assessment. Treatment includes acute and preventive options, with calcitonin gene-related peptide inhibitors and neuromodulation as newer strategies. Complementary therapies and botulinum toxin injections may also benefit those with chronic migraine.