Approximately 5% of kids experiencing chronic headaches will be diagnosed with migraines, and some children have them as early as four years old. By junior high school, most boys who have migraines will outgrow them; on the other hand, migraine frequency usually increases in teenage girls due to hormonal changes.

Migraine is frequently referred to as a vascular headache, because when a migraine occurs, it is the result of blood vessels either constricting or narrowing (vasoconstriction), or expanding or dilating (vasodilation).

Vasoconstriction does not produce pain, but it can temporarily affect vision or balance. When the blood vessels dilate, however, their expansion causes the painful part of the migraine, the headache, and can result in decreased appetite, nausea, and possible vomiting.