A migraine is a primary headache disorder characterized by recurrent headaches that are moderate to severe. Typically, the headaches affect one half of the head, are pulsating in nature, and last from two to 72 hours. Associated symptoms may include nausea, vomiting, and sensitivity to light, sound, or smell. The pain is generally made worse by physical activity. Up to one-third of people have an aura: typically a short period of visual disturbance that signals that the headache will soon occur. Occasionally, an aura can occur with little or no headache following it.Migraines are 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 migraines affect slightly more boys than girls before puberty and two to three times more women than men. The risk of migraines usually decreases during pregnancy. 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 may be added to the above. A number of medications are useful to prevent attacks including metoprolol, valproate, and topiramate.Globally, approximately 15% of people are affected by migraines. It most often starts at puberty and is worst during middle age. In some women they become less common following menopause. 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 BCE in ancient Egypt. The word "migraine" is from the Greek ἡμικρανία (hemikrania), "pain on one side of the head", from ἡμι- (hemi-), "half", and κρανίον (kranion), "skull".