Each attack must last 4 to 72 hours and have two of the following four paincharacteristics: unilateral location, pulsating quality, moderate to severe intensity, and aggravation by routine physical activity. In addition, the attacks must be associated with at least one of the following: nausea, vomiting, or photophobia and phonophobia. With these criteria, no single characteristic is mandatory for a diagnosis of migraine. A patient who has severe pain aggravated by routine activity, photophobia and phonophobia, meets these criteria as does the more typical patient with unilateral throbbing pain and nausea. Migraine usually lasts several hours or the entire day. When the migraine persists for longer than three days, the term "status migrainosus" is used. Frequency of attacks varies widely from a few per lifetime to several per week. The average migraineur experiences from one to three headaches a month.