Phentermine is a prescription medication used along with a doctor-approved, reduced-calorie diet, exercise, and behavior change program to help you lose weight. It is used by certain overweight people, such as those who are obese or have weight-related medical problems.

Phentermine belongs to a class of drugs known as sympathomimetic amines. It is thought to work by decreasing your appetite, increasing the amount of energy used by your body, or affecting certain parts of the brain. This medication is an appetite suppressant and belongs to a class of drugs called sympathomimetic amines.

Phentermine should not be used with certain other drugs and some foods since a serious, possibly fatal drug interaction may occur. Phentermine should not be taken with other weight loss medications (weight loss drugs, including prescribed drugs, over-the-counter drugs, and herbal products). If you are in doubt, check with your doctor or pharmacist for further advice.

The drug is available under several brand names, including Adipex or Adipex-P, and it can be used short-term (a few weeks), as part of a larger weight-loss plan that includes diet, behavioral changes, and exercise.