Phentermine is a prescription medication used for short-term weight loss management in individuals who are overweight or obese. It is classified as a sympathomimetic amine and works as an appetite suppressant to help reduce food intake and aid in weight reduction. Phentermine is typically prescribed as part of a comprehensive weight loss program that includes a reduced-calorie diet, increased physical activity, and behavior modification. It is intended for short-term use (a few weeks) because its effects on appetite tend to diminish over time.