Phentermine is a prescription weight loss medicine that is only approved for short-term use. It comes in both tablet and capsule form, and is usually taken by mouth once daily (although some people need to take it twice a day). Phentermine capsules come in four different strengths, while the tablets are only available in one strength.
This medication primarily works by suppressing the appetite, but it may also increase metabolism. Phentermine is chemically related to amphetamines and is classified as a controlled substance in the United States, meaning it has the potential to be abused and is regulated by strict laws.
Only very short studies have evaluated the effectiveness phentermine capsules and tablets. In these studies, people taking these medications lost more weight than those not taking them, but the difference was small (only a fraction of a pound more per week for the people taking the weight loss medication). Studies also suggest that the effects of these drugs on weight loss decrease after the first few weeks.
(Click Phentermine to learn more about the effects of this medication, suggestions on when and how to take phentermine capsules and tablets, and what side effects may occur.)
