A migraine progresses through four distinct phases: prodrome, aura, headache, and postheadache (or postdrome). Not every migraineur will experience every phase; some don't have auras and others don't have a prodrome. The feature virtually all share is the headache phase, which can last anywhere from four hours to three days. Rarely, some people experience a migraine aura without headache.

Prodrome

Symptoms that anticipate the start of a migraine attack are known as the prodrome phase of the migraine. Not everyone experiences a prodrome — it's estimated that between 25 and 60 percent of migraineurs experience prodromal symptoms anywhere from one to twenty-four hours prior to a migraine attack. Prodrome can occur in both migraine with aura and migraine without aura.

Prodromal symptoms can be physical and mental in nature. The most common reported symptoms are fatigue and mood changes such as irritability, depression, and euphoria. Gastrointestinal symptoms such as diarrhea, constipation, and stomach pain are also reported. Other prodromal symptoms include neck pain, sensitivity to smell and light, hearing loss, dizziness, yawning, weakness, food cravings, tingling of the head and/or extremities, and nose and sinus problems. Migraineurs may experience some, all, or none of these symptoms.

Aura

An estimated 20 percent of people with migraine experience an aura before or during headache. Aura symptoms can vary dramatically from person to person and can include tingling and/or numbness in the fingers, difficulty speaking or coming up with the right word (known as dysphasia), and motor weakness. The most common type of aura is visual disturbance. This often occurs as flickering spots or lines or areas of loss of vision. Imaging studies have shown that during a migraine aura, changes occur in blood flow to the brain and cerebral metabolic activity (see All about Auras section, page 12).

Headache

Migraine headache pain is triggered by a complex cascade of neurochemical and inflammatory responses involving the brainstem and vascular structures in the head. The pain usually occurs on one side of the head, often around the eye or temple, and is typically described as throbbing or pulsating. Migraine pain builds in intensity as the headache progresses and may generalize to involve both sides of the head. Physical activity — even routine movement such as standing from a sitting position, climbing stairs, or bending over to pick something up — intensifies the discomfort.

During the headache phase of migraine, the migraineur may experience heightened sensitivity to light and sound. Stomach upset is also very common; for this reason medications that stop nausea and vomiting (antiemetics) are frequently prescribed to migraineurs. Migraine headaches — both with and without aura — can last anywhere from four hours to three days, sometimes persisting through sleep.

Postdrome

Once the head pain of migraine resolves, patients may experience what is known as the postdrome — or what some migraineurs call the headache hangover. This phase may last anywhere from a few hours to more than a day. Fatigue, cognitive difficulties, mood change, dizziness, weakness, and a low-grade headache are all common features of postdrome.

Because all of these symptoms may initially appear during migraine headache or even before the headache during prodrome, researchers aren't sure whether postdrome is a distinct phenomenon or if it's just a continuation and lessening of headache symptoms.

There have been only a few clinical studies of postdromes, but they seem to indicate that patients who experience a postdrome tend to have higher intensity migraine pain and more migraine triggers. They also are more likely to experience prodrome and aura.