A Long-Term Safety and Tolerability Extension Study Evaluating Atogepant for the Prevention of Chronic or Episodic Migraine

\- Eligible participants who completed Visit 7, and Visit 8 if applicable, of Study 3101-303-002 or Study 3101-304-002 without significant protocol deviations and who did not experience an Adverse Event that may indicate an unacceptable safety risk.

* Participants requiring any medication, diet, or nonpharmacological treatment on the list of prohibited concomitant medications or treatments that cannot be discontinued or switched to an allowable alternative. * Participants with an ECG indicating clinically significant abnormalities at Visit 1. * Participants with hypertension at Visit 1. * Participants with a significant risk of self-harm, or of harm to others; participants who report suicidal ideation with intent, with or without a plan, since the last visit, must be excluded. * Participants with clinically significant hematologic, endocrine, cardiovascular, pulmonary, renal, hepatic, gastrointestinal, or neurologic disease.