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Qsymia (phentermine/topiramate)

Qsymia (phentermine/topiramate): Qsymia, a combination of phentermine and topiramate, was approved by the FDA in 2012. It helps patients lose weight by suppressing appetite and increasing feelings of fullness. Side effects include dizziness, dry mouth, and constipation.

Era of Discovery


Mechanism of Action

Combination of appetite-suppressing drugs

History of Use in the United States

Approved by FDA in 2012

Benefit of Weight Loss Agent or Medication

Weight loss due to appetite suppression and increased fullness

Possible Side Effects

Dizziness, dry mouth, constipation

Current Regulatory Status in US

Available by prescription

Qsymia: A Pioneering Combination Therapy with a Rocky Journey

Qsymia, a combination drug containing phentermine and topiramate, was touted as an innovative solution in the fight against obesity. However, its journey from conception to market has been marked by a series of unexpected twists and turns, including initial promise, naming changes, underwhelming performance, and the bankruptcy of its parent company.

Initial Promise: Phentermine and Topiramate

The story of Qsymia starts with the individual histories of its components. Phentermine, an appetite suppressant, has long been used for weight loss. Topiramate, on the other hand, was initially approved in 1996 for seizure control and later for migraine prevention. However, clinicians noticed that patients taking topiramate often lost weight, which sparked interest in its potential for treating obesity.

A California-based physician was the first to recognize the combined weight loss potential of phentermine and topiramate. This combination showed promise due to phentermine's appetite-suppressing properties and topiramate's weight loss side effect.

Birth of Vivus and QNexa

Vivus Pharmaceuticals was formed to develop this combination drug, initially named QNexa. The company saw a potential market in the growing obesity epidemic and aimed to provide a novel solution.

Name Change to Qsymia and FDA Approval

The name QNexa was later changed to Qsymia, and the drug was approved by the FDA in 2012. It was one of the first weight loss drugs approved in the US in over a decade, heralding a new era in obesity treatment.

Lackluster Performance and Bankruptcy

Despite initial hopes, Qsymia's performance in the market was disappointing. Part of this could be attributed to its side effects, which include taste changes (like flat-tasting soda), memory loss, and paresthesia. Despite the modest weight loss observed in clinical trials, these side effects, combined with the high cost of the drug, likely contributed to its underperformance.

In 2020, Vivus filed for bankruptcy, a stark contrast to the initial optimism that accompanied Qsymia's launch.

Off-label Use and Zonisamide

Off-label use of topiramate and phentermine (prescribed separately) is common due to the high cost of Qsymia. Some evidence suggests this combination might be even more effective than Qsymia, though more research is needed.

Interestingly, another antiepileptic drug, zonisamide, has similar effects to topiramate, including weight loss. Some doctors use zonisamide as an alternative to topiramate for weight loss, though this is also an off-label use.

The Journey Continues

Despite the setbacks, Qsymia's story is a reminder of the complex challenges in developing effective obesity treatments. It underscores the importance of a comprehensive approach that considers not only the effectiveness of a treatment but also its side effects, cost, and overall impact on patients' quality of life. The experience with Qsymia provides valuable insights that can guide future research and drug development in this critical area of healthcare.

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