There are now five GLP-1-based prescription medicines approved for long-term weight management in the U.S.: three injections and two daily pills. They differ in how much weight people lose in trials, how often you take them, who they are approved for, and what else they are approved to treat. Tick what matters to you below, and the tool highlights the options that match and sorts them for you.
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About this tool: based on FDA prescribing information and the main published trial for each medicine, checked in 2026. It is for comparison only and is not a recommendation. These are prescription medicines, and the right choice depends on your health history. See our medical disclaimer.
Who these medicines are approved for
All five are approved for chronic weight management, alongside a reduced-calorie diet and more physical activity, in adults with:
- a body mass index (BMI) of 30 or higher (obesity), or
- a BMI of 27 or higher (overweight) plus at least one weight-related condition, such as high blood pressure, type 2 diabetes or high cholesterol.
Wegovy injection and Saxenda are also approved for teenagers aged 12 and older with obesity, based on BMI percentiles for age and sex.
How they work
GLP-1 (glucagon-like peptide-1) is a gut hormone released after eating. It tells the brain you are full, slows how quickly the stomach empties, and helps the pancreas release insulin. GLP-1 receptor agonists mimic this hormone for much longer than the natural version lasts, which reduces appetite and food cravings. Tirzepatide (Zepbound) also activates a second hormone receptor, GIP, which is thought to explain why it produced more weight loss in trials. Orforglipron (Foundayo) is a small-molecule GLP-1 drug rather than a peptide, which is why it can be absorbed as a pill without strict fasting rules.
Weight loss: what the trials found
| Medicine | Main trial | Average weight loss | Placebo |
|---|---|---|---|
| Zepbound 15 mg | SURMOUNT-1, 72 weeks | About 21% | About 3% |
| Wegovy injection 2.4 mg | STEP 1, 68 weeks | About 15% | About 2% |
| Wegovy pill 25 mg | OASIS 4, 64 weeks | About 14% | About 2% |
| Foundayo | ATTAIN-1, 72 weeks | About 11% (highest dose) | About 2% |
| Saxenda 3 mg | SCALE, 56 weeks | About 8% | About 3% |
These are averages. In every trial, some people lost much more and some lost little, and results depended on staying on the full dose. Studies such as the 2023 SURMOUNT-4 trial show that most people regain a substantial part of the weight within a year of stopping, which is why these medicines are intended for long-term use.
Side effects they share
The most common side effects for all five are digestive: nausea, diarrhea, vomiting, constipation, stomach pain and indigestion. They are usually worst when starting or increasing the dose, which is why every medicine starts low and is raised gradually over several weeks or months. Less common but serious risks listed in FDA labeling include pancreatitis, gallbladder problems such as gallstones, kidney problems from dehydration, low blood sugar when combined with insulin or sulfonylureas, and a faster heart rate. The injectable GLP-1 medicines and oral semaglutide carry a boxed warning about thyroid C-cell tumors seen in rodent studies, and they should not be used by people with a personal or family history of medullary thyroid cancer or multiple endocrine neoplasia type 2 (MEN 2).
Other things to discuss with your prescriber
- Pregnancy: stop these medicines before trying to conceive. Wegovy’s label advises stopping at least two months before a planned pregnancy.
- Birth control pills: tirzepatide can reduce how well oral contraceptives work for four weeks after starting and after each dose increase. A backup or non-oral method is recommended during those times.
- Surgery and sedation: because stomach emptying slows, tell your surgical team you take a GLP-1 medicine before any procedure.
- Cost and coverage: insurance coverage for weight loss varies widely. Manufacturers now sell some forms directly to patients at a lower cash price, and the daily pills are generally priced below the injections.
- Compounded versions: the FDA has warned about dosing errors and quality problems with compounded semaglutide and tirzepatide. FDA-approved products are the safer choice.
Older non-GLP-1 options
Phentermine (a short-term appetite suppressant), Qsymia (phentermine with topiramate) and Contrave (naltrexone with bupropion) are older weight-loss medicines that cost less but produced smaller average weight loss in trials. Our comparisons of Wegovy vs phentermine and Ozempic vs phentermine explain the trade-offs.
Related reading
- Wegovy vs Saxenda: weekly vs daily
- Saxenda vs Victoza: same drug, different dose
- Mounjaro vs Trulicity
- Rybelsus vs metformin
- Waist-to-height ratio calculator
- A1C to average glucose calculator
Frequently asked questions
Which GLP-1 medicine causes the most weight loss?
In trials, tirzepatide (Zepbound) produced the largest average weight loss, about 21% at the highest dose. In the head-to-head SURMOUNT-5 trial, it led to more weight loss than semaglutide (Wegovy).
Is the Wegovy pill as effective as the injection?
Close. The 25 mg pill produced about 14% average weight loss in its main trial, compared with about 15% for the weekly injection in its trial. The pill must be taken daily on an empty stomach.
What is the difference between Foundayo and the Wegovy pill?
Both are once-daily pills. Foundayo (orforglipron) has no food or water timing rules, while the Wegovy pill must be taken on an empty stomach with a small sip of water, then 30 minutes before food. The Wegovy pill produced somewhat more weight loss in its trial.
Do you regain weight after stopping a GLP-1 medicine?
Most people regain a substantial part of the lost weight within a year of stopping, according to trials such as SURMOUNT-4 and STEP 1’s extension. Obesity is treated as a chronic condition, so these medicines are designed for long-term use.
Are Ozempic and Wegovy the same?
Both contain semaglutide, but Ozempic is approved for type 2 diabetes at doses up to 2 mg, while Wegovy is approved for weight management at 2.4 mg. Similarly, Mounjaro and Zepbound are both tirzepatide.
Sources
- Wegovy, Zepbound, Saxenda and Foundayo prescribing information, DailyMed and Drugs@FDA
- Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). NEJM. 2021. PubMed
- Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). NEJM. 2022. PubMed
- Pi-Sunyer X, et al. A randomized, controlled trial of 3.0 mg of liraglutide in weight management (SCALE). NEJM. 2015. PubMed
- FDA approves oral semaglutide for weight management. AJMC, December 2025
- Lilly’s weight-loss pill wins FDA approval. C&EN, April 2026
About this article
Written by the Health Linear Editorial Team from primary sources such as FDA prescribing information, DailyMed, NIH and peer-reviewed studies, which are linked in the article. Last updated October 27, 2026.
Read our editorial process and medical disclaimer. Spotted an error? Tell us and we will correct it.