"i have been taking phentermine for only about 4 days now. but i have lost 8 pounds. i am also taking another pill, for depression and anxiety for about a month, so i&#039;m not sure if all my side effects are from only phentermine, but i have been having lots. i have been unable to sleep for more than a couple hours a night, a migraine on day 3 that sent me home and put me in bed all day, little to no appetite, irritability, and diarrhea for a day now. however, i&#039;ve been reading that these side effects only last for a week in some people so i&#039;m going to wait and see. the weight loss part is working so far. i&#039;ve just had to force myself to eat food throughout the day. if this drug works it will be worth it."