"had my first follow up today, been on phentermine for 25 days and i&#039;m down 19 lbs. few side affects...cotton mouth, anxiety occasionally like twice a day for a brief period and constipation which has lead to hemorrhoids. but, given the success of 19 pounds in 25 days, they side effects are definitely not severe enough to stop. i thought about stopping if the weight wasn&#039;t coming off but it definitely is. i encourage you to use my fitness pal and track what you eat as well. i&#039;m a 6&#039;4 male that started at 322 pounds. all i eat is between 1200-1500 calories per day and feel great!"