What Is Phentermine and Topiramate Used For?

Some people may consider using phentermine and topiramate to help with weight loss. Specifically, this prescription diet drug is designed for those who are obese or have a weight-related medical problem like type 2 diabetes. Phentermine and topiramate is thought to work by activating certain chemicals in the brain, which helps people eat less and feel full faster.

An Overview of Uses for Phentermine and Topiramate

Phentermine and topiramate (Qsymia®) is a prescription medication approved to help certain adults who are overweight or obese to lose weight and maintain a healthy weight. It contains a combination of two medicines, phentermine and topiramate.
Overweight and obese are terms used to describe weighing more than what is considered a healthy weight. Both terms are defined based on body mass index (BMI), which is calculated using a person's height and weight. A person is considered overweight if they have a BMI between 25 and 29.9 kg/m2. A BMI of 30 or greater is considered obese.
(Click BMI Calculator to calculate your BMI.)
Obesity and being overweight are serious public health problems in the United States. In 2009 and 2010, more than one-third of all adults in the U.S. were considered obese, and experts believe that number is on the rise. The main problem with being overweight or obese is that weighing too much significantly increases your risk for developing many health problems. This includes but is not limited to:
(Click Health Effects of Obesity to learn more about the potential consequences of weighing too much.)
Weight gain occurs when a person consumes more calories from food than he or she is able to burn. However, being overweight or obese is much more complex than that. These are complex health problems influenced by a number of things, including a person's genetics, the environment, behavior, and other medical conditions (see Causes of Obesity). All of these factors make it impossible to find a "one size fits all" answer to help people lose weight.  
There are numerous programs, diets, medications, and other treatments available for people who want to lose weight; however, many do not offer long-term success. Experts generally agree that it takes more than just eating less to lose weight and keep the weight off. A healthy diet and regular physical activity are important parts of any weight loss plan.
Phentermine and topiramate may be able to help certain overweight or obese adults manage their weight, when used in combination with a reduced-calorie diet and exercise. It is specifically approved for use in adults who have a BMI of:
  • 30 or greater
  • 27 or greater with at least one weight-related medical problem, such as type 2 diabetes, hypertension, or high cholesterol.

At this time, it is unknown whether losing weight with phentermine and topiramate will actually reduce your risk for heart problems or a stroke. It is also unknown whether this drug is safe when used with other weight loss products.
Last reviewed by: Kristi Monson, PharmD
5 Common Relationship Mistakes for Adults With ADHD