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Last updated: Apr 29, 2021
7 min read

5 FDA-approved weight loss pills and medications for long-term treatment

Mike Bohl, MD, MPH, ALMchimene richa

Medically Reviewed by Mike Bohl, MD, MPH, ALM

Written by Chimene Richa, MD


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

Having obesity is more than just not fitting into your clothes; it is a chronic medical condition that affects many people worldwide. In the United States, more than 73% of adults over the age of 20 have measurements in the overweight or obese range—that’s more than two out of every three adults (Fryar, 2020). For some people, diet and exercise are not enough. Read on to learn more about FDA-approved weight loss pills and medications that can help you lose weight and keep it off. 


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Lose an average of 15% of your body weight

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weight loss

Lose an average of 15% of your body weight

Learn more
Learn more

How do you know if you have obesity?

The most accessible way is by checking your Body Mass Index (BMI). BMI is a measurement of your body weight in kilograms (1 kilogram equals 2.2 pounds) divided by your height in meters squared (1 meter equals ~3 feet 3 inches). You can easily calculate your BMI by clicking here. Using your BMI, you can determine which of the following categories applies to you:

If your BMI is higher than 25, you have an increased risk of several health conditions, including heart disease, stroke, diabetes, and severe COVID-19. Losing as little as 5–10% of the excess weight can significantly improve your health. Weight loss medications, in addition to diet, exercise, and lifestyle modifications, are appropriate for some people to help with their weight loss goals. 

What are weight loss pills?

Weight loss drugs work in different ways and are not for everyone. People who are pregnant, trying to become pregnant, or breastfeeding should not use these medications. Weight management medications are meant for people with the following:

Short-term weight loss pills

The Food and Drug Administration (FDA) has approved four medications for short-term use (up to 12 weeks) to help achieve weight loss: 

  • Phentermine
  • Benzphetamine
  • Diethylpropion
  • Phendimetrazine

These drugs are all stimulants that work by making you feel full faster so that you eat less. Some of these medications are Schedule IV, meaning that they have a higher potential for drug abuse (Perreault, 2021). Potential side effects of these short-term weight loss pills include increased heart rate, high blood pressure, trouble sleeping (insomnia), dry mouth, constipation, and nervousness.

People with heart disease, poorly controlled high blood pressure, or a history of addiction or drug abuse should not use these medications. Never take weight loss pills if you are pregnant or breastfeeding (Perreault, 2021). 

Long-term weight loss pills and medications

Given all of the risks of the short-term weight-loss drugs, most healthcare providers turn to treatments approved for longer time frames. There are currently five medications approved by the FDA for the long-term treatment of weight loss:

These five drugs are all considered effective at helping people achieve at least 5% weight loss after using them for one year (Khera, 2016).  

Lorcaserin (brand name Belviq), a previously approved weight loss drug, has recently been withdrawn from the U.S. market. The FDA asked the manufacturing company, Eisai Inc., to voluntarily recall lorcaserin because of an increased cancer occurrence (FDA, 2020).

How do weight loss pills work?

The FDA-approved weight loss pills work in different ways, including (Perrault, 2021):

  • Acting as an appetite suppressant (decreasing your desire to eat) 
  • Reducing how much fat you absorb from the foods you eat
  • Making you feel full faster, so you eat less

Continue reading to learn more about specific weight loss pills. 

Phentermine/topiramate (brand name Qsymia)

Phentermine/topiramate is a combination of phentermine and the anti-seizure drug topiramate; using both drugs together works better than either drug alone to reduce appetite. Because of the potential for abuse, it is considered a scheduled drug by the DEA. You should avoid using phentermine/topiramate if you have high blood pressure or coronary heart disease (Perrault, 2021). 

Side effects include dry mouth, constipation, paraesthesias (numbness/tingling), depression, anxiety, and elevated heart rate (Perrault, 2021).

Liraglutide (brand name Saxenda)

Liraglutide is an injectable drug that is a member of the GLP-1 agonist drug class, most commonly used to treat type 2 diabetes. Studies have shown that it can also help you lose weight. Liraglutide affects how fast your stomach empties and the hormonal changes that occur after you eat a meal. The end result? You feel less hungry and eat less (Kelly, 2020). Another benefit is that people with diabetes and cardiovascular disease have fewer heart attacks and strokes when taking liraglutide compared to placebo (Marso, 2016).  

Common side effects include nausea, vomiting, diarrhea, and low blood sugar. In rare cases, it can increase your risk of pancreatitis. Lastly, animal studies have shown that it may increase the risk of thyroid tumors—so far, clinical trials have not demonstrated an increase in thyroid tumors. However, people with a history of pancreatitis or thyroid tumors should avoid this medication (Perrault, 2021).

Semaglutide (brand name Wegovy)

Semaglutide, like liraglutide, is also a GLP-1 agonist and injectable drug used to treat diabetes. While there is an oral pill, only the injectable form is FDA-approved to treat obesity (Perrault, 2021). A recent study shows that more than two thirds of people who took semaglutide lost at least 5% of their body weight compared to those taking a placebo. This drug also helped improve blood pressure and cholesterol measurements (Davies, 2021).

Common side effects include mild to moderate nausea, vomiting, diarrhea, and constipation, which are usually temporary.  As with any medication used to treat diabetes, low blood sugar is a potential side effect (Davies, 2021).

Naltrexone/bupropion (brand name Contrave)

Naltrexone treats drug and alcohol dependence, while bupropion can improve depression and help people quit smoking. The combination of these two medications may affect dopamine, a brain chemical. By doing so, this drug reduces food cravings and decreases your appetite (Onakpoya, 2020). 

Common side effects of naltrexone/bupropion include nausea, headaches, constipation, insomnia, vomiting, dizziness, and dry mouth. Some people also notice elevations in blood pressure and heart rate while using naltrexone/bupropion. Since this combo medication includes bupropion, an antidepressant, it may increase the risk of suicide in young adults with depression when they first start treatment (a known side effect of antidepressants). 

People with uncontrolled high blood pressure, seizure disorders, eating disorders, chronic opioid use, severe liver failure should avoid using this drug. Also, anyone who has used monoamine oxidase inhibitors (MAOIs) in the past 14 days should not take naltrexone/bupropion because of the risk of serious side effects and drug interactions (Perrault, 2021). 

Orlistat (brand names Xenical, Alli)

Orlistat works by decreasing the absorption of fats from your food—it reduces fat absorption by up to 30% (Gorgojo-Martínez, 2019). Orlistat is available in prescription strength (brand name Xenical) and a lower strength over-the-counter formulation (brand name Alli). Not only is orlistat effective for losing weight, but it can also help you lower your blood pressure and cholesterol (Perreault, 2021). 

Most of the side effects of orlistat affect your gastrointestinal (GI) system, including stomach rumbling, abdominal cramps, bloating, and constipation. Some of the more distressing GI effects include (Perreault, 2021):

  • Passing gas (sometimes with oily spotting)
  • Diarrhea, loose stools, or greasy stools
  • Frequent bowel movements that are hard to control
  • Liver damage (rare effect)

Fortunately, most of these issues improve after using it for a while. Also, you can avoid some of them by sticking to a low-fat diet. Other side effects include poor absorption of fat-soluble vitamins (vitamins A, D, E, and K) and kidney stones (Perreault, 2021).

Do weight loss pills replace diet and exercise? 

Absolutely not! Nothing can replace exercising and healthy diet choices when it comes to your health and weight management. Treating obesity with drugs should only be used as a part of an overall program that includes lifestyle modifications, like diet and exercise, counseling, and behavioral interventions. Adding lifestyle changes may help you minimize weight regain once you stop the weight loss pills (LeBlanc, 2018). 

People taking weight loss medications along with lifestyle modifications lose, on average, 7–10% of their initial weight after one year. These compounding effects may improve your risk of multiple health problems like type 2 diabetes and high blood pressure (Yanovski, 2014). 

Find a sustainable path for you

Weight loss medications may be the added boost you need to help you lose weight; however, they are not for everyone. Talk to your healthcare provider about your options for losing weight with prescription medications to see if any are right for you. Remember that weight loss is most successful and sustainable if you combine it with lifestyle changes, like a healthier diet and more physical activity.


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  2. Gorgojo-Martínez, J. J., Basagoiti-Carreño, B., Sanz-Velasco, A., Serrano-Moreno, C., & Almodóvar-Ruiz, F. (2019). Effectiveness and tolerability of orlistat and liraglutide in patients with obesity in a real-world setting: The XENSOR Study. International Journal of Clinical Practice, 73(11), e13399. doi: 10.1111/ijcp.13399. Retrieved from https://pubmed.ncbi.nlm.nih.gov/31397946/
  3. Kelly, A. S., Auerbach, P., Barrientos-Perez, M., Gies, I., Hale, P. M., Marcus, C., et al. (2020). A randomized, controlled trial of liraglutide for adolescents with obesity. The New England Journal of Medicine (NEJM), 382(22), 2117–2128. doi: 10.1056/NEJMoa1916038. Retrieved from https://pubmed.ncbi.nlm.nih.gov/32233338/
  4. Khera, R., Murad, M. H., Chandar, A. K., Dulai, P. S., Wang, Z., Prokop, L. J., et al. (2016). Association of Pharmacological Treatments for Obesity with weight loss and adverse events. JAMA, 315(22), 2424. doi: 10.1001/jama.2016.7602. Retrieved from https://pubmed.ncbi.nlm.nih.gov/27299618/
  5. LeBlanc, E. S., Patnode, C. D., Webber, E. M., Redmond, N., Rushkin, M., & O’Connor, E. A. (2018). Behavioral and pharmacotherapy weight loss interventions to prevent obesity-related morbidity and mortality in adults: updated evidence report and systematic review for the US Preventive Services Task Force. JAMA, 320(11), 1172–1191. doi: 10.1001/jama.2018.7777. Retrieved from https://pubmed.ncbi.nlm.nih.gov/30326501/
  6. Marso, S. P., Daniels, G. H., Brown-Frandsen, K., Kristensen, P., Mann, J. F., Nauck, M. A., et al. (2016). Liraglutide and cardiovascular outcomes in type 2 diabetes. The New England Journal of Medicine, 375(4), 311–322. doi: 10.1056/NEJMoa1603827. Retrieved from https://pubmed.ncbi.nlm.nih.gov/27295427/
  7. Onakpoya, I. J., Lee, J. J., Mahtani, K. R., Aronson, J. K., & Heneghan, C. J. (2020). Naltrexone-bupropion (Mysimba) in management of obesity: A systematic review and meta-analysis of unpublished clinical study reports. British Journal of Clinical Pharmacology, 86(4), 646–667. doi: 10.1111/bcp.14210. Retrieved from https://pubmed.ncbi.nlm.nih.gov/31918448/
  8. Perreault, L. (2021) Obesity in adults: Drug therapy. In: UpToDate. Pi-Sunyer, X. & Kunins, L. (Eds.). Retrieved from https://www.uptodate.com/contents/obesity-in-adults-drug-therapy
  9. U.S. Food and Drug Administration (FDA). (2020). FDA requests the withdrawal of the weight-loss drug Belviq, Belviq XR (lorcaserin) from the market. Retrieved on Apr 27, 2021 from https://www.fda.gov/drugs/drug-safety-and-availability/fda-requests-withdrawal-weight-loss-drug-belviq-belviq-xr-lorcaserin-market
  10. Yanovski, S. Z., & Yanovski, J. A. (2014). Long-term drug Treatment for obesity. JAMA, 311(1), 74. doi: 10.1001/jama.2013.281361. Retrieved from https://pubmed.ncbi.nlm.nih.gov/24231879/

Dr. Mike is a licensed physician and the Director, Medical Content & Education at Ro.