"gained 80lbs due to disabling injury and several surgeries and lack of inactivity. have been on phentermine for 1 week. had headache first two days, no other side effects except only sleep about 4 hours a night but feel rested. anyway i&#039;ve lost 10lbs so far. you do have to eat because if i don&#039;t make myself i wont. have energy but not nervous, have high blood pressure (under control with medicines for years) no affect on it at all so far but keep it checked daily."