[retsof]

I am on day 10 with phentermine. If I had it to do over again, I would start with the a low dose, like 1/4 of a 37.5 mg pill upon waking. Once you tolerate that okay, then take 1/4 pill when you wake up and 1/4 pill in the early afternoon. If you're getting results with that much, stay with it until you feel like you need more. If you tolerate that okay and need more, up the AM dose to 1/2 pill followed by 1/4 pill in the early afternoon. Then go up to the full 37.5 mg pill when you feel like you need it.
(BTW, if you're on time-released phentermine, this info may not apply.)
I struggled with whopper headaches the first night, even with only 1/2 a 37.5 mg pill. I tried a whole 37.5 mg pill a few days later and had awful insomnia. So I hope this advice might help newbies. You can buy a pill cutter at most drugstores for about $2. (It only works for tablets, not capsules.)
I am on Day 10 and up to 3/4 of a 37.5 mg. pill. I still have a little trouble getting to sleep, but doing much better. The amount I'm taking doesn't completely kill my appetite; it just helps me with control. Drink lots of water and incorporate exercise as a regular part of your life.
You still need to revise your habits, which takes work, but phentermine can help.