Migraine is a chronic neurological disorder characterized by moderate to severe headaches, and nausea, vomiting, and light sensitivity. A migraine headache is a form of vascular headache. Migraine headache is caused by vasodilatation (enlargement of blood vessels) that causes the release of chemicals from nerve fibres that coil around the large arteries of the brain. Enlargement of these blood vessels stretches the nerves that coil around them and causes the nerves to release chemicals. The chemicals cause inflammation, pain, and further enlargement of the artery. The increasing enlargement of the arteries magnifies the pain.

Some people who get migraines have warning symptoms, called an aura, before the actual headache begins. An aura is a group of symptoms, including vision disturbances that are a warning sign that a bad headache is coming.