Phentermine is a prescription medication used for short-term weight loss in adults with a body mass index (BMI) of 30 or higher. It is also used in people who are overweight (BMI of 27 or higher) and have other health conditions related to obesity, such as type 2 diabetes, high blood pressure, or high cholesterol.
Phentermine works by decreasing appetite and increasing energy expenditure. It is usually taken once or twice a day, before meals. The typical starting dose is 15 mg per day, which may be increased to 30 mg per day if necessary.