While defined by the "less than 15 days" threshold, the severity of Episodic Migraine varies significantly among patients. It is often stratified clinically to determine treatment intensity:
is a neurological disorder characterized by a history of recurrent migraine attacks occurring on a limited number of days per month. The formal definition, as established by the International Headache Society (IHS) in the International Classification of Headache Disorders, 3rd edition (ICHD-3) , is defined by the number of headache days per month: episodic migraine definition
To be classified as migraine (either with or without aura), a patient must have experienced at least five attacks fulfilling the following criteria: While defined by the "less than 15 days"
According to the published by the International Headache Society (IHS), Episodic Migraine is defined by the frequency of attacks and the presence of specific symptom criteria. 3rd edition (ICHD-3)