"i started taking phentermine 6 weeks ago. i have only lost 6 lbs. however, i feel like i&#039;m on an emotional roller-coaster and i&#039;m not sure if it is because of the medication. some days i just want to cry for no reason at all. it also makes me sleepy. not jittery. i have always had trouble sleeping so i can&#039;t say it has caused my insomnia. it does make you not hungry though. i have to remind myself to eat. sex drive seems to be disappearing too. "