Jenny Niwa, National Center for Health Research
You have probably heard about several very popular new weight loss drugs, such as Wegovy, Ozempic, Mounjaro, and Zepbound. Although Ozempic and Mounjaro are specifically approved by FDA for treating diabetes and not for weight loss, all four are being used by people who want to lose weight. Before you decide whether to take these drugs, here are some things you should know.
What are these drugs and how do they work?
The FDA approved Ozempic in 2017 for the treatment of type 2 diabetes and Wegovy in 2021 for weight loss for adults with obesity or who are overweight and have at least one weight-related health condition. Their popularity really exploded 6 years later, in 2023. Mounjaro was approved in the spring of 2022 for Type 2 diabetes and Zepbound was approved in late 2023 for those with obesity or who are overweight with an additional chronic condition such as hypertension. While Ozempic and Mounjaro are not approved specifically for weight loss, doctors may prescribe them anyway – that’s called prescribing it off-label. All four curb hunger and reduce the intake of food. The medications are currently administered by injection once a week, but they may soon be available in pill form.
Both Wegovy and Ozempic are made of semaglutide. Mounjaro and Zepbound are made of tirzepatide. Both mimic the GLP-1 hormone, which is made naturally by the body. GLP-1 does 2 things: 1) It slows the passage of food through the stomach, which helps people feel fuller longer; and 2) it promotes insulin release and helps reduce blood sugar.
What do research studies say?
In August 2023, Wegovy’s maker, Novo Nordisk, claimed in a press release that the drug reduced the risk of serious heart problems. The company described a randomized trial of 17,500 patients with obesity and heart disease, although patients with diabetes were excluded.[2] Half of the participants received regular injections of Wegovy and the other half received a placebo. Rather than publish the results in a peer-reviewed journal, Novo Nordisk publicized their research in a press release that claimed that Wegovy reduced heart attacks, strokes, and deaths by 20% compared to placebo, and this was widely reported in the media. However, this statistic is misleading because it is a relative risk. When the study was finally published in the New England Journal of Medicine on November 11, 2023, the detailed results did not sound as impressive: 8% of the people in the placebo group had had a nonfatal stroke or heart attack or died due to cardiovascular causes, compared to 6.5 percent in the Wegovy group. [3] That decrease from 8% to 6.5% is a 20% decrease, but the difference is only 1.5% for patients considering whether it is a meaningful difference for them.
In August 2023, a study published in the New England Journal of Medicine found that the medication reduced the risk of heart problems for diabetes patients who were at high risk for cardiovascular complications. [4] This study included more than 3,000 patients with type 2 diabetes, who were randomly assigned to receive once-weekly Ozempic or a placebo for 2 years. Results showed that 108 of 1648 patients (6.6%) taking Ozempic either died, had a nonfatal heart attack, or nonfatal stroke, compared to 146 of 1649 patients (8.9%) who took the placebo. This was statistically significant (which means it did not occur by chance), but is a difference of only 2.3%.
Mounjaro has been found to reduce blood pressure, which could improve health, but no published studies have provided evidence that it reduces heart disease.
What are the side effects?
The most common side effects of these GLP-1 medications include stomach issues such as nausea and diarrhea. Some patients experienced persistent vomiting or cyclic vomiting syndrome and severe gastroparesis. Gastroparesis is stomach paralysis and occurs when there is a delay or stopping in food movement from the stomach to the small intestine.
Warnings about other possible serious side effects that are listed on the companies’ websites include inflammation of the pancreas, gallbladder problems, increased risk of low blood sugar, kidney problems, serious allergic reactions, change in vision for people with type 2 diabetes, increased heart rate, and depression and thoughts of suicide.[5]
In January 2024, a new FDA report listed potential links between the medications and extensive hair loss (called alopecia), a swallowing problem that can occur during surgery called aspiration, and thoughts of suicide.[6] A few days later, the FDA announced that their preliminary review did not support an increase in thoughts of suicides among patients taking these drugs, but the FDA also said they had drawn no conclusions based on their preliminary findings and would continue to review new data. Experts agree that thoughts of suicide are difficult to evaluate in the kinds of studies that have been conducted.
In 2025, researchers reported that women who had started taking Ozempic or Wegovy were twice was likely to experience hair loss than those starting the weight loss drug Contrave.[7] There was no difference between men taking these different types of drugs. The article is published as a “preprint,” which means that it has not yet been published in a peer-reviewed medical journal.
An even more serious side effect is the risk of thyroid cancer. According to a study conducted by the European Medicines Agency (EMA, which is the European version of the FDA), researchers found that using GLP-1 medications for 1-3 years may increase the risk for all types of thyroid cancers.[8]
Concerns about aspiration during surgery remain.[9] In 2023, the American Society of Anesthesiologists (ASA) advised that people taking GLP-1 drugs should make sure to stop taking the medication a week before surgery.[10] Everyone who plans to have surgery is advised not to eat for 24 hours before surgery, but since these drugs affect how long food stays in the stomach, a 24-hour fast is not enough to prevent regurgitating food during the operation. That would be dangerous because vomiting under anesthesia can cause pneumonia and other fatal problems due to the food and stomach acid getting into the lungs.[11] As of late 2024, the ASA no long recommends that everyone taking GLP-1 medications should stop taking them a week before surgery, but suggested that patients taking GLP-1 medications who have a high risk of aspiration should switch to a liquid diet prior to surgery.[12] Patients should keep in mind that the risk of aspiration may be impossible to prevent if someone taking the drug requires emergency surgery.
Do You Keep Losing Weight? What Happens if you Stop Taking the Drug?
Most weight loss strategies work for a limited time. People hit a plateau and stop losing weight. And of course, if people stop dieting or exercising, they gain the weight back. Is the same true for the new weight loss drugs such as semaglutide and tirzepatide?
Unfortunately, as noted earlier in this article, many patients who take these drugs stop taking them within a year. For example, in 2023, a published study by researchers at the Cleveland Clinic of more than 1,900 patients found that only 19% of people who are prescribed medications like Wegovy and Ozempic for weight-loss or diabetes are still taking the drugs a year later.[13] A 2024 study by Reuters based on an analysis of U.S. pharmacy claims found that 37% of Semaglutide patients had stopped taking the drug by 3 months and 60% by 1 year.[14] And as noted earlier, a study published in 2025 of more than 125,000 women and men found that half of diabetes patients and almost two-thirds of non-diabetes patients stop taking the GLP-1 within a year.[15]
Regardless of whether they stopped taking the drugs due to side effects, cost, or other reasons, the long-term benefits of these drugs are limited because when they stop taking the drugs, their stomach no longer feels full. A study conducted with almost 2,000 adults with at least one weight-related co-morbidity (such as hypertension, obstructive sleep apnea, or cardiovascular disease) found that one year after no longer taking Wegovy, participants regained an average of two-thirds of their prior weight loss.[16]
But even those who continue to take the drug hit a plateau, often after approximately 1 year.[17] As is often the case with weight loss strategies, they just stop losing weight. If they stop taking the drug, they are likely to gain back most of the weight they lost.
There is still much that is unknown about these drugs. It is unclear how these drugs affect patients after years of use, whether the drugs are effective at maintaining a certain weight after long-term use, and what percentage of people will only benefit if they stay on the drug for the rest of their lives. Current literature suggests that such medications need to be taken life-long to experience long-term benefits and prevent any negative consequences that come from discontinuing use. [13]
Other Questions to Consider
In 2022, Novo Nordisk spent a total of $11 million to promote their Ozempic and other weight-loss drugs, including $9 million on meals and $2 million on travel for thousands of doctors to promote their weight-loss drugs.[18] That included more than 457,000 meals; nearly 12,000 prescribers had food paid for by the company more than a dozen times in that one year. Buying meals for doctors is not illegal, but this extreme level of “generosity” raises concerns. If these drugs are so effective, why did the company think it necessary to provide all these free meals? And since the drugs became much more popular after the company spent all that money providing free meals to doctors, do you wonder if doctors are prescribing these drugs because they have they been unduly influenced to prescribe them?
Is taking these weight loss drugs right for you?
Ozempic is FDA approved for patients with type 2 diabetes and is not approved for weight loss. Due to the risk of thyroid cancer, if you or any family member has ever had a type of thyroid cancer, taking any of these 4 drugs may be dangerous. Similarly, if you have sensitivity to gastrointestinal problems, these drugs may not be right for you.
In January 2024, Eli Lilly, the maker of Mounjaro and Zepbound reminded physicians and patients that GLP-1 drugs are meant for serious diseases (obesity or Type 2 diabetes) and not for cosmetic weight loss.[19]
Another thing to consider is the cost, which is much higher in the U.S. compared to other countries.[20] If insurance does not cover the cost, one monthly dose of Ozempic costs about $1,000, and the cost for Wegovy is about $1,350 per month.[21],[22] The cost of Mounjaro is similar to Ozempic and Zepbound costs about $520. Since they are relatively new, there are no generic versions. You may be able to lower the costs of these drugs through savings programs or through coverage on your health insurance plan. Many private insurance providers cover these drugs to treat Type 2 diabetes. When used for weight-loss purposes, it is much less likely to be covered. In 2025, Medicare is paying for the drugs to treat diabetes but not for weight loss, and despite those restrictions the cost could result in an increase in Medicare premiums.
The media attention to these 4 drugs makes it seem that they are the only FDA-approved weight loss drugs. They are not. However, all weight loss drugs have unpleasant and potentially serious side effects, and these 4 seem to be more effective.
If you are eligible and interested in taking these drugs, you should first and foremost make sure to talk to your physician and discuss what to expect, the possible side effects, and your medical history. If you are not eligible for these drugs or are not interested in using them, there are other methods available that can help you lose weight and improve your health if you stick with them. These include exercising daily or regularly, developing healthier eating habits, and knowing when to eat.
[1]Hoffman, S. (2023) The Differences between Saxenda and Wegovy. Very Well Health. https://www.verywellhealth.com/the-differences-between-saxenda-and-wegovy-7564310
[2] Chen, E., and Joseph, A. (2023). Novo’s obesity drug Wegovy lowers cardiovascular risk by 20%, landmark trial finds. STAT+. https://www.statnews.com/2023/08/08/novo-nordisk-wegovy-cardiovascular-risk/
[3] Lincoff, A. M., Brown-Frandsen, K., Colhoun, H. M., Deanfield, J., Emerson, S. S., Esbjerg, S., Hardt-Lindberg, S., Hovingh, G. K., Kahn, S. E., Kushner, R. F., Lingvay, I., Oral, T. K., Michelsen, M. M., Plutzky, J., Tornøe, C. W., & Ryan, D. H. (2023). Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. New England Journal of Medicine. https://doi.org/10.1056/NEJMoa2307563
[4] Marso, S., Bain, S., Consoli, A., & Eliaschewitz, F. (2016). Semaglutide and Cardiovascular Outcomes in Patients with Type 2 Diabetes. The New England Journal of Medicine. https://www.nejm.org/doi/full/10.1056/nejmoa1607141
[5] Novo Nordisk. (n.d.). Tips for managing common side effects. https://www.wegovy.com/dashboard/my-library/week-02-tips-for-managing-common-side-effects.html#:~:text=thoughts%20of%20suicide.-,The%20most%20common%20side%20effects%20of%20Wegovy%C2%AE%20may%20include,runny%20nose%20or%20sore%20throat.
[6] FDA Looking Into New Risks With Popular Weight-Loss Drugs. (n.d.). Retrieved January 9, 2024, from https://www.usnews.com/news/health-news/articles/2024-01-04/fda-looking-into-new-risks-with-popular-weight-loss-drugs
[7] Sodhi, M., Rezaeianzadeh, R., Kezouh, A., Frey, C., & Etminan, M. (2025). Risk of Hair Loss with Semaglutide for Weight Loss (p. 2025.02.23.25322568). medRxiv. https://doi.org/10.1101/2025.02.23.25322568
[8] Bezin, J., Gouverneur, A., Penichon, M., Mathieu, C., Garrel, R., Hillaire-Buys, D., Pariente, A., & Faillie, J.L. (2022). GLP-1 Receptor Agonists and the Risk of Thyroid Cancer. Diabetes Care. https://diabetesjournals.org/care/article-abstract/46/2/384/147888/GLP-1-Receptor-Agonists-and-the-Risk-of-Thyroid?redirectedFrom=fulltext
[9] Yeo, Y. H., Gaddam, S., Ng, W. H., Huang, P.-C., Mohamed, G., Samaan, J., Hsieh, T. Y.-J., Lee, G. Y., Watson, R., Mathur, R., Ma, K. S.-K., & Rezaie, A. (2024). Increased Risk of Aspiration Pneumonia Associated With Endoscopic Procedures Among Patients With Glucagon-like Peptide 1 Receptor Agonist Use. Gastroenterology, 167(2), 402-404.e3. https://doi.org/10.1053/j.gastro.2024.03.015
[10] American Society of Anesthesiologists. (2023, November 1). Drugs for Diabetes or Weight Loss: What To Know Before Surgery. Made For This Moment | Anesthesia, Pain Management & Surgery. https://madeforthismoment.asahq.org/preparing-for-surgery/risks/drugs-diabetes-weight-loss/
[11] Goodman, B. (2023). They took blockbuster drugs for weight loss and diabetes. Now their stomachs are paralyzed. CNN. https://www.cnn.com/2023/07/25/health/weight-loss-diabetes-drugs-gastroparesis/index.html
[12] American Society of Anesthesiologists. (2024, October 29). Most Patients Can Continue Diabetes, Weight Loss GLP-1 Drugs Before Surgery, Those at Highest Risk for GI Problems Should Follow Liquid Diet Before Procedure. https://www.asahq.org/about-asa/newsroom/news-releases/2024/10/new-multi-society-glp-1-guidance
[13] Gasoyan, H., Pfoh, E. R., Schulte, R., Le, P., & Rothberg, M. B. (2024). Early‐ and later‐stage persistence with antiobesity medications: A retrospective cohort study. Obesity, 32(3), 486–493. https://doi.org/10.1002/oby.23952
[14] Terhune, C. (2023). Exclusive: Most patients using weight-loss drugs like Wegovy stop within a year, data show. Reuters. https://www.reuters.com/business/healthcare-pharmaceuticals/most-patients-using-weight-loss-drugs-like-wegovy-stop-within-year-data-show-2023-07-11/
[15] Rodriguez, P. J., Zhang, V., Gratzl, S., Do, D., Goodwin Cartwright, B., Baker, C., Gluckman, T. J., Stucky, N., & Emanuel, E. J. (2025). Discontinuation and Reinitiation of Dual-Labeled GLP-1 Receptor Agonists Among US Adults With Overweight or Obesity. JAMA Network Open, 8(1), e2457349. https://doi.org/10.1001/jamanetworkopen.2024.57349
[16] Wilding, J. P. H., Batterham, R. L., Davies, M., Van Gaal, L. F., Kandler, K., Konakli, K., Lingvay, I., McGowan, B. M., Oral, T. K., Rosenstock, J., Wadden, T. A., Wharton, S., Yokote, K., Kushner, R. F., & STEP 1 Study Group. (2022). Weight regain and cardiometabolic effects after withdrawal of semaglutide: The STEP 1 trial extension. Diabetes, Obesity and Metabolism, 24(8), 1553–1564. https://doi.org/10.1111/dom.14725
[17] The GLP-1 Agonist Plateau No One’s Talking About. (2023, September 22). https://www.medpagetoday.com/special-reports/exclusives/106464
[18] Florko, N. (2023). Novo Nordisk bought prescribers over 450,000 meals and snacks to promote drugs like Ozempic. STAT+. https://www.statnews.com/2023/07/05/ozempic-rybelsus-novo-nordisk-meals-for-doctors/#:~:text=Novo%20Nordisk%20bought%20prescribers%20over,to%20promote%20drugs%20like%20Ozempic&text=WASHINGTON%20%E2%80%93%20Novo%20Nordisk%20spent,weight%20loss%2Dinducing%20diabetes%20drugs
[19] An Open Letter From Eli Lilly and Company Regarding Certain Practices Related to Mounjaro® and Zepbound® | Eli Lilly and Company. (2024, June 20). https://investor.lilly.com/news-releases/news-release-details/open-letter-eli-lilly-and-company-regarding-certain-practices
[20] Amin, K., Telesford. I., Singh, R., & Cox, C. (2023). How do prices of drugs for weight loss in the US compare to peer nations’ prices? Health System Tracker. https://www.healthsystemtracker.org/brief/prices-of-drugs-for-weight-loss-in-the-us-and-peer-nations/?utm_campaign=morning_rounds&utm_medium=email&_hsmi=270760455&_hsenc=p2ANqtz-_P2SZN9DLjS_l7fSn8hrgS8xRf4YvJIonV0X-iRtKF3FtcWbgsMJd-K6tDV2u12XNFMEesDCulwlbdwkw74D1S-2WqXQ&utm_content=270760453&utm_source=hs_email#List%20prices%20of%20drugs%20used%20for%20weight%20loss%20in%20the%20U.S.%20and%20peer%20nations
[21] Wilson, A. (2023). How much does Ozempic cost without insurance?. RO. https://ro.co/weight-loss/ozempic-cost-without-insurance/
[22] Wilson, A. (2023). How much does Wegovy cost? RO. https://ro.co/weight-loss/wegovy-cost/