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Belviq, or lorcaserin, is a weight-loss drug approved to treat obesity. Its distributor, Eisai Inc., pulled it off the market in the United States in 2020 at the request of the U.S. Food and Drug Administration. The FDA cited increased rates of lung, pancreatic and colorectal cancer among Belviq users during a five-year study of the drug’s risk.

Belviq hit the market in 2012 offering weight-loss hope to people who struggled with obesity. It was also sometimes used to treat overweight people who also had a serious medical condition, such as high blood pressure, high cholesterol or diabetes.

It was the first weight-loss drug approved by the FDA in 13 years. Unlike over-the-counter diet pills or appetite suppressants which are often intended for cosmetic weight loss, Belviq was a prescription drug used to treat obesity.

Obesity and being overweight are two different things. Being overweight simply means weighing too much. Obesity means having potentially dangerous amounts of body fat. Obesity is a chronic condition that can increase a person’s risk for serious health problems including heart disease, diabetes and certain types of cancer.

How Does Belviq Work?

Belviq (pronounced bell-VEEK) works by controlling appetite. The drug activates serotonin receptors in the brain. Serotonin is a neurotransmitter that triggers feelings of well-being such as satisfaction, gratification and being fully fed.

Antidepressants called SSRIs target some serotonin receptors that play a role in a patient’s mood. Belviq only targets the ones that affect appetite.

People take regular versions of Belviq tablets twice a day. Extended-release tablets are taken only once per day. A person on Belviq is supposed to lose five percent of his or her weight during the first 12 weeks of taking the drug when coupled with a low-calorie diet. If this amount of weight loss is not achieved, Belviq treatment should be stopped.

Belviq Side Effects May Include Cancer

On Feb. 13, 2020, the FDA requested that Belviq’s manufacturer, Eisai Inc., voluntarily withdraw the drug over a potential cancer link. The agency based its decision on results from a five-year study of Belviq users.

The research showed an increased risk of three types of cancer among people in the study taking Belviq.

Types of increased cancer risks the FDA attributed to Belviq
  • Pancreatic cancer
  • Colorectal cancer
  • Lung cancer

Source: U.S. Food and Drug Administration

Eisai stated that its interpretation of the five-year study differed from the FDA’s. Out of respect for the agency’s decision, however, the company worked with them to remove the drug from the market.

Common Belviq Side Effects

Prior to the FDA action in 2020, the most common Belviq side effects appeared to be minor. The package insert listed 11 side effects that occurred in more than five percent of patients who took Belviq during clinical trials.

Common Belviq side effects in non-diabetic patients:
  • Constipation
  • Dizziness
  • Dry mouth
  • Fatigue
  • Headache
  • Nausea
Common Belviq side effects in patients with diabetes:
  • Hypoglycemia
  • Headache
  • Back pain
  • Cough
  • Fatigue

Source: U.S. Food and Drug Administration

Other Serious Belviq Side Effects

Because Belviq activates serotonin receptors in the brain, it may cause serious interactions with SSRI antidepressants such as Paxil or Prozac.

Belviq side effects that require immediate medical attention include:
  • Easy bleeding or bruising
  • Mental or mood changes
  • Confusion
  • Thoughts of suicide
  • Depression
  • Difficulty with memory or concentration
  • Unusual agitation
  • Shaking or twitching muscles
  • Changes in heart rate
  • Unexplained fever
  • Swelling of the hands, feet or ankles
  • Shortness of breath
  • Breast swelling and unusual breast milk discharge
  • Erections lasting 4 hours or more
  • Sensations of standing outside your body

What People Who Took Belviq Should Do

The FDA recommended that people stop taking Belviq and talk to their doctors or other health care professionals about alternatives. It also advised that doctors stop prescribing and dispensing the drug. And it recommended that doctors contact patients taking Belviq and warn them about the cancer risk.

The agency did not recommend any special cancer screening for people on Belviq.

The FDA advised people to safely dispose of any unused Belviq at a neighborhood drug takeback location. It also provided instructions on safe disposal if there is no nearby takeback center.

How to safely dispose of unused Belviq
  1. Do not crush Belviq pills — instead mix them with dirt, cat litter, used coffee grounds or some other unappealing material.
  2. Place the mixture in a sealed container or plastic bag.
  3. Throw the mixture into your home trash can.

People should also remove all personal information on the labels of empty Belviq bottles before throwing them into the trash or recycle bin.

People who developed cancer after taking the drug have filed Belviq lawsuits to cover medical costs, lost wages and other costs associated with cancer.

If you have developed cancer after taking Belviq, or noticed other side effects while taking it, you should also report your problems to the FDA’s MedWatch program. You can report online or download a form to mail in. You can also request a form at 1-800-332-1088.

Belviq Pills
Belviq (Lorcaserin) Facts
  1. Uses Used with diet and exercise to treat obesity
  2. Side Effects Pancreatic cancer, colorectal cancer, lung cancer, headache, dizziness, fatigue, nausea, back pain, low blood sugar, constipation, cough, dry mouth
  3. Manufacturer Eisai Inc., Arena Pharmaceuticals
  4. Active Ingredient Lorcaserin
  5. Administration Route Oral
  6. Available Strength 10, 20 mg
  7. Dosage Form Tablet
  8. Drug Class Serotonin Receptor Agonists
  9. Is Available Generically False
  10. Is Proprietary True
  11. RxCUI 1300707

Please seek the advice of a medical professional before making health care decisions.

Related Pages
Terry Turner
Written By Terry Turner Writer

Terry Turner has been writing articles and producing news broadcasts for more than 25 years. He covers FDA policy, proton pump inhibitors, and medical devices such as hernia mesh, IVC filters, and hip and knee implants. An Emmy-winning journalist, he has reported on health and medical policy issues before Congress, the FDA and other federal agencies. Some of his qualifications include:

  • American Medical Writers Association (AMWA) and The Alliance of Professional Health Advocates member
  • Centers for Disease Control and Prevention Health Literacy certificates
  • Original works published or cited in Washington Examiner, MedPage Today and The New York Times
  • Appeared as an expert panelist on hernia mesh lawsuits on the BBC
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  5. Otto, M.A. (2020, February 13). Lorcaserin Withdrawn from U.S. Market Due to Cancer Risk. Clinical Endocrinology News. Retrieved from
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  7. Ryan, G. (2014, January 30). FDA Tells Consumers to Avoid 4 Weight-Loss Supplements. Law360. Retrieved from
  8. U.S. Food and Drug Administration. (2020, February 13). FDA Requests the Withdrawal of the Weight-Loss Drug Belviq, Belviq XR (Lorcaserin) From the Market. Retrieved from
  9. U.S. Food and Drug Administration. (2020, February 13). Safety Clinical Trial Shows Possible Increased Risk of Cancer With Weight-Loss Medicine Belviq, Belviq XR (Lorcaserin). Retrieved from
  10. U.S. National Library of Medicine. (2018, April). Prescribing Information, Belviq. Retrieved from
  11. U.S. National Library of Medicine. (2020, February 13). Obesity. Retrieved from
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