Attack frequency

Attack frequency refers to the number of headache (or pain) attacks per time period (usually one month). Successful relief of a migraine attack with medication may be followed by a relapse of the same attack within 48 hours. To distinguish an attack relapse from a new attack, the International Headache Society Guidelines for Controlled Trials of Drugs in Migraine, 2nd edition, recommend that a new attack is likely if it was preceded by an entire headache-free day.