How Does Phentermine Work?

Phentermine is a prescription weight loss medication approved for short-term use only. It is approved for individuals with a body mass index (BMI) of 30 or greater or a BMI of 27 or greater if other risk factors are present, such as high cholesterol or diabetes.

How does phentermine work? It works by suppressing the appetite, and it may also increase the metabolism. This medication is chemically related to amphetamines.

Only short studies have evaluated the effectiveness of drugs like phentermine. In these studies, people taking these medication lost more weight than those not taking them, but the difference was small (a fraction of a pound more per week for the people taking the weight loss drug). Studies also suggest that the effects of these medicines for weight loss decrease after the first few weeks.

(Click Phentermine Uses for more information on how phentermine works for weight loss, to learn more about the specific effects of this medicine, and to find out whether this product is approved for treating obesity in children.)