Migraine Preventive Medications and Weight Gain Certain drugs that are used to try to prevent migraines can cause weight gain of up to 40 pounds. Prescription medications like Depakote (valproic acid), Pamelor (nortriptyline, an anti-depressant) or Elavil (amitriptyline, another anti-depressant) are known to result in substantial weight gain in some patients. Beta-blocker drugs like Inderal (propranolol hydrochloride) can cause rapid weight gain that may be related to heart dysfunction. Weight-change effects require careful consideration when selecting migraine-preventive medications, and weight...