Can i take phentermine and thyroid medication at the same time? i am also taking sprintec birth control.

Yes, but: You need to take the thyroid medication if your thyroid level is abnormal. The Phentermine will only affect it if your dose of either is excessive. The phentermine, however, only works for as long as you take it - then you'll begin to gain the weight back unless you've learned how to eat properly - if you have, you don't need the Phentermine in the first place.