"For years, patients would say they got a migraine because they ate chocolate or pizza or a hot dog, " says Dr. Saper.

WSJ: Stopping a Migraine Before It Starts

For example, "Many people tell us that they vomit yesterday's food, " says Joel Saper, director of the Michigan Head-Pain and Neurological Institute in Ann Arbor.

WSJ: Stopping a Migraine Before It Starts