What Is It?

A migraine is a very common, but very particular, type of headache. Most people who get migraines have repeated attacks of headaches that occur over many years. The typical migraine headache is throbbing or pulsating, and often is associated with nausea and changes in vision. While many migraines are severe, not all severe headaches are migraines, and some migraines can be quite mild.

Up to 20% of people in the United States will experience migraine headaches at some point in life. In about half of those, migraine headaches first appear during childhood or adolescence. Two-thirds of people who get migraines are women, probably because of the influence of hormones. Migraines also tend to run in families.

Despite years of research, scientists do not know exactly why migraines occur. The pain of migraines is associated with swelling in blood vessels and irritation of nerves that surround the brain. The brain chemical serotonin appears to play an important role in this process as it does in other conditions, including depression and eating disorders.

Symptoms

A migraine usually is a throbbing headache that occurs on one or both sides of the head. The headache typically is accompanied by nausea, vomiting or loss of appetite. Activity, bright light or loud noises can make the headache worse, so someone having a migraine often seeks out a cool, dark, quiet place. Most migraines last from four to 12 hours, although they can be shorter or much longer.

One unique feature of migraines is an unusual sensation that a migraine is about to occur. This sensation is called a prodrome. Prodrome symptoms can include fatigue, hunger and nervousness. Migraines also have typical aftereffects, such as a feeling of exhaustion that lasts a day or two after a severe migraine headache has faded. Not all people who get migraines have prodromes or aftereffects.

Another unique feature of migraines is an aura. In a typical aura, a person suddenly will develop blurry or distorted vision or will see pulsating lights. These changes in vision will come and go over 15 to 30 minutes and alert someone that a headache is about to begin. Sometimes, auras affect the sense of hearing, smell or taste. Only some people who get migraines have auras, and they don't accompany every headache. An aura also can occur without being followed by a headache. Rarely, migraines can cause unusual neurological symptoms such as dizziness, loss of vision, passing out, numbness, weakness or tingling.

Migraines can be triggered by certain activities, foods, smells or emotions. Some people are more likely to experience migraines when they are under stress, while others develop migraines when stress is relieved (for example, the day after exams or an important meeting). Women who have migraines often find that their headaches occur or worsen around the time of their menstrual periods.