"it takes a while to kick in, and you have to gradually increase your dosage - like, start at 25mg twice a day, then every 2 weeks, 25 mg more - gradually increase to the max dosage your doc wants you on. otherwise the more negative side effects will be more pronounced. i am on this medication for migraines, and the weight loss is a &quot;side effect.&quot; it took about 6 months before i saw any weight loss at all, so i was frustrated at first, though the migraines did start to subside a bit. now, i&#039;ve been on it a year, and i&#039;ve gone from 235 lbs. to 205 lbs. without trying at all. like, i&#039;m not exercising any more than i was, i haven&#039;t been dieting at all that i&#039;m aware of - i just don&#039;t crave food like i used to. headaches better too."