"i&#039;ve been using phentermine for 3 months now. my doctor gave me a 30 day supply, but i still haven&#039;t finished it. i take it every other day, or every 2 days. before i took the pills i weighed 238lbs. i just had a baby in january (3rd child), and i wanted to take the pills to help me lose the weight. i went in last month for an appointment and i&#039;m down to 194lbs. so, it does work. but sometimes i get headaches, or i get very tired, and need to take a 30 minute nap and that&#039;s why i take it every other day."