Migraine (UK: , US: ) is a common neurological disorder characterized by recurrent headaches. Typically, the associated headache affects one side of the head, is pulsating in nature, may be moderate to severe in intensity, and could last from a few hours to three days. Non-headache symptoms may include nausea, vomiting, and sensitivity to light, sound, or smell. The pain is generally made worse by physical activity during an attack, although regular physical exercise may prevent future attacks. Up to one-third of people affected have aura: typically, it is a short period of visual disturbance that signals that the headache will soon occur. Occasionally, aura can occur with little or no headache following, but not everyone has this symptom.

Migraine is believed to be due to a mixture of environmental and genetic factors. About two-thirds of cases run in families. Changing hormone levels may also play a role, as migraine affects slightly more boys than girls before puberty and two to three times more women than men. The risk of migraine usually decreases during pregnancy and after menopause. The underlying mechanisms are not fully known. They are, however, believed to involve the nerves and blood vessels of the brain.

Initial recommended treatment is with simple pain medication such as ibuprofen and paracetamol (acetaminophen) for the headache, medication for the nausea, and the avoidance of triggers. Specific medications such as triptans or ergotamines may be used in those for whom simple pain medications are not effective. Caffeine in combination with other analgesics is safe and effective in treatment of acute migraine. A number of medications are useful to prevent attacks including metoprolol, valproate, and topiramate.

Globally, approximately 15% of people are affected by migraine. In the Global Burden of Disease Study of 2010, it was ranked as the third most prevalent disorder in the world. It most often starts at puberty and is worst during middle age. As of 2016, it is one of the most common causes of disability. An early description consistent with migraines is contained in the Ebers papyrus, written around 1500 BC in ancient Egypt. The word migraine is from the Greek ἡμικρᾱνίᾱ (hēmikrāníā), 'pain in half of the head', from ἡμι- (hēmi-), 'half' and κρᾱνίον (krāníon), 'skull'.