A recent study investigated this important subject; even if a headache med. works, nobody is happy if they gain 30lb. Surprisingly, Prozac topped the list of weight gainers; even more than the tricyclic nortryptylline. Depakote did, as we know, cause weight gain, but less than Prozac. Topomax (topiramate) was the only one to cause weight loss. In utilizing headache meds, we are always trying to avoid side effects, and weight gain is a primary one.