Wegovy® vs Zepbound® is probably the exact search that brought you here. Maybe a friend lost weight on one of them. Maybe your doctor mentioned the other, and you are not sure which one fits your body.
Both drugs promise real weight loss, and both come from serious clinical research, not hype. But the trial numbers behind them are different enough to matter for your choice. You deserve to see those numbers before anyone tells you which one to pick.
I read the actual trial data behind both brands, including the one study that put them head to head. Below, you will find the real percentages, the dosing schedule, the side effects, and my honest take on who each medication tends to fit best.
KEY TAKEAWAYS
- Zepbound® (tirzepatide) produced more weight loss than Wegovy® (semaglutide) in the SURMOUNT-5 head-to-head trial: 20.2% versus 13.7% at 72 weeks.
- Wegovy® is the only one with published heart-protection data: a 20% drop in cardiovascular events (SELECT trial).
- Zepbound® also treats moderate-to-severe sleep apnea in adults with obesity, a use Wegovy® does not have.
- Wegovy® now comes as a daily pill too, approved in December 2025, not just a weekly shot.
- Both drugs share the same top side effects (nausea, diarrhea, constipation) and the same thyroid warning.
What readers want to figure out
- What is the real difference between Wegovy® and Zepbound®?
- Which one leads to more weight loss, based on actual trial data?
- How do the weekly doses and side effects compare?
- What is the boxed warning both drugs carry?
- What changed for 2026, and which one should I ask my doctor about?
Here is how I will walk through this. First the fast comparison, then the mechanism, then each drug’s own trial data, then the head-to-head study that settled the biggest question. After that, dosing, side effects, the safety warning, and what is new this year.
Wegovy® vs Zepbound®: the fast comparison
| Attribute | Wegovy® | Zepbound® |
|---|---|---|
| Active drug | Semaglutide (GLP-1 receptor agonist) | Tirzepatide (dual GIP/GLP-1 receptor agonist) |
| Maker | Novo Nordisk | Eli Lilly and Company |
| FDA approval for weight loss | June 4, 2021 | November 8, 2023 |
| Own-brand trial | STEP 1: 14.9% body weight loss, 68 weeks, N=1,961 | SURMOUNT-1: 20.9% body weight loss (15 mg), 72 weeks, N=2,539 |
| Head-to-head result (SURMOUNT-5, 72 weeks, N=751) | 13.7% body weight loss | 20.2% body weight loss |
| Form | Weekly injection (pen); also a daily pill since Jan 2026 | Weekly injection (pen or vial) only |
| Typical maintenance dose | 2.4 mg weekly (or 1.7 mg) | 5, 10, or 15 mg weekly |
| Top side effects | Nausea, diarrhea, vomiting, constipation | Nausea, diarrhea, vomiting, constipation |
| Extra approved use | Cuts major cardiovascular events by 20% (SELECT trial) | Treats moderate-to-severe sleep apnea with obesity |
| Boxed warning | Thyroid C-cell tumors (rodent data) | Thyroid C-cell tumors (rodent data) |
Figures come from FDA prescribing labels and the SURMOUNT-5 trial (Aronne et al., NEJM 2025). All results reflect the FDA-approved brand-name products.
Both drugs use the same eligibility rule. You typically qualify with a BMI of 30 or higher. A BMI of 27 or higher also works if you have a weight-related condition, like high blood pressure or type 2 diabetes.
Two gut hormones usually beat one. That is the short version of why Zepbound® tends to edge out Wegovy® on the scale.
The mechanism gap: why two hormones might beat one
Wegovy® contains semaglutide. Semaglutide copies GLP-1, a hormone your gut releases after you eat. GLP-1 tells your brain you are full and slows down digestion.
Zepbound® contains tirzepatide. Tirzepatide copies GLP-1 and a second hormone called GIP. Researchers believe the added GIP activity helps explain why tirzepatide tends to produce more weight loss.
Both hormones occur naturally in your body after meals. Semaglutide and tirzepatide simply turn up that signal for a full week at a time, instead of minutes.
Wegovy® and the STEP 1 numbers
The STEP 1 trial tested Wegovy® against a placebo shot in 1,961 adults with obesity or overweight. Nobody in the trial had diabetes.
After 68 weeks, people on Wegovy® lost an average of 14.9% of their starting body weight. The placebo group lost 2.4%. That gap was one of the largest ever recorded for a weight-loss drug at the time.
For someone who weighs 220 pounds, 14.9% works out to about 33 pounds. Results vary by person, and some people lose more or less than the trial average.
Zepbound® and the SURMOUNT-1 numbers
The SURMOUNT-1 trial tested three doses of Zepbound® against a placebo shot in 2,539 adults with obesity or overweight. Diabetes was also an exclusion here.
At the highest dose, 15 mg, people lost an average of 20.9% of body weight over 72 weeks. The placebo group lost 3.1%. The 10 mg and 5 mg groups still beat placebo, at 19.5% and 15.0%.
Fewer people quit the Zepbound® groups than the placebo group, about 14% to 16% versus 26%. That suggests side effects did not drive most people off the drug.
The head-to-head trial: what SURMOUNT-5 actually found
STEP 1 and SURMOUNT-1 were separate trials with different people, so you cannot compare them directly. SURMOUNT-5 fixed that. It put Zepbound® and Wegovy® in the same 751-person trial.
Every participant got the highest dose they could tolerate. Zepbound® users could reach 15 mg. Wegovy® users could reach 2.4 mg, the approved ceiling for each drug.
After 72 weeks, the Zepbound® group lost 20.2% of body weight. The Wegovy® group lost 13.7%. Waist size dropped more too, 18.4 cm versus 13.0 cm.
Nearly two out of three people on Zepbound® reached at least 15% weight loss, versus two out of five on Wegovy®. Side effects in both groups were mostly mild stomach issues during dose increases.
One limit is worth knowing. SURMOUNT-5 was not blinded, so participants knew which drug they were taking. That can shape how people report side effects, even when the weight numbers are objective.
SURMOUNT-5 is the closest thing this field has to a fair fight. Zepbound® won it on the scale, but Wegovy® still holds the only heart-protection data.
What the first few months look like on either drug
1. Week 1: you start at the lowest dose, 0.25 mg for Wegovy® or 2.5 mg for Zepbound®, once a week.
2. Weeks 2 to 4: your body adjusts. Mild nausea or a full feeling after small meals is common.
3. Every 4 weeks: your prescriber raises the dose in steps, watching how you tolerate each one.
4. Weeks 12 to 20: most people reach a maintenance dose, 2.4 mg for Wegovy® or 5 to 15 mg for Zepbound®.
5. Ongoing: you stay on the maintenance dose long term, with regular check-ins to track weight and side effects.
Side effects: is one easier on your body?
Nausea, diarrhea, vomiting, and constipation top both drug labels. If you have taken one GLP-1 medication before, expect a similar feeling on the other.
Wegovy®’s label also lists headache, fatigue, and dyspepsia among common reactions. Zepbound®’s label adds fatigue, injection-site reactions, and burping to its own list.
In the SURMOUNT-5 head-to-head trial, most side effects in both arms were mild to moderate stomach symptoms. They showed up mostly around dose increases, not randomly throughout treatment.
Neither drug wins a clear side-effect contest in the data. Your own history with nausea or a sensitive stomach matters more than the averages.
The boxed warning both drugs share
Wegovy® and Zepbound® both carry an FDA boxed warning, the strongest label warning the agency uses. In rodent studies, both drugs caused thyroid C-cell tumors.
Nobody knows yet if this happens in humans. The FDA states that the human relevance of this rodent finding has not been determined for either drug.
Both drugs are off-limits if you or a close family member has had medullary thyroid cancer. The same is true if you have Multiple Endocrine Neoplasia syndrome type 2. Tell your prescriber about your thyroid history before you start either one.
What’s new for 2026: the Wegovy® pill
Zepbound® is still injection-only in 2026. Wegovy® is not. The FDA approved a daily Wegovy® pill in December 2025, and it reached pharmacies in January 2026.
The pill comes in four doses: 1.5 mg, 4 mg, 9 mg, and 25 mg, taken once a day. It uses the same semaglutide found in the injection, just swallowed instead of injected.
In the OASIS 4 trial, 307 adults took the 25 mg pill or a placebo for 64 weeks. People who stayed on treatment the whole time lost 16.6% of body weight, versus 2.7% on placebo. Counting everyone, including those who stopped early, the average was 13.6% versus 2.4%.
If needles are the reason you have put off treatment, this pill is worth asking about. Eli Lilly has an oral tirzepatide version in testing, but it has no FDA approval yet, so Zepbound® still means a weekly shot for now.
A pill does not change the biology, but it changes who is willing to start. That alone makes 2026 a real turning point for Wegovy®.
So which one wins in 2026?
There is no universal winner here, and I would be skeptical of anyone who tells you there is. The SURMOUNT-5 trial gives Zepbound® the edge for raw weight loss.
If you are chasing the biggest number on the scale and a needle does not bother you, ask about Zepbound® first. The 20.2% average is the best documented result of the two.
If you have known heart disease alongside your weight, Wegovy® has something Zepbound® does not have. The SELECT trial showed a 20% drop in major cardiovascular events. That data point can matter more than a few extra pounds for some people.
If sleep apnea is part of your health picture, Zepbound® has its own distinct edge. It became the first medication ever approved specifically for moderate-to-severe sleep apnea with obesity, back in December 2024.
If a weekly needle is the dealbreaker, the new Wegovy® pill changes the math. It will not match the injection’s numbers exactly, but it removes the biggest barrier for a lot of people who never started.
One more thing. All these numbers come from trials of the FDA-approved brand-name drugs. They do not apply to compounded semaglutide or tirzepatide, which are not FDA-approved and were never tested in STEP 1, SURMOUNT-1, or SURMOUNT-5.
Insurance coverage often settles the debate before biology does. If your plan covers one and not the other, that practical reality usually wins. Ask your prescriber to check both before you decide.
FREQUENTLY ASKED QUESTIONS
SURMOUNT-5 is the only trial that tested both drugs in the same group of people. Zepbound® (tirzepatide) produced 20.2% average weight loss over 72 weeks, and Wegovy® (semaglutide) produced 13.7% in the same trial. That is a real, measured difference, though individual results still vary from person to person.
Wegovy® contains semaglutide, which copies one gut hormone, GLP-1. Zepbound® contains tirzepatide, which copies GLP-1 and a second hormone, GIP. Both are weekly injections approved for weight management. Zepbound® produced more weight loss in the SURMOUNT-5 head-to-head trial, while Wegovy® has separate trial data showing it lowers cardiovascular risk.
Neither one clearly wins or loses here. Both drugs share the same top four side effects: nausea, diarrhea, vomiting, and constipation. In the SURMOUNT-5 trial, most side effects in both groups were mild to moderate. They mostly showed up around dose increases, not randomly throughout treatment.
Switching between the two is a common conversation with prescribers, though neither FDA label provides an official conversion chart between them. Most prescribers restart the new drug at its lowest dose and re-titrate slowly, the same way you started the first time. Tell your prescriber every dose you have taken so far.
Both drugs carry the FDA’s strongest warning label because of thyroid C-cell tumors seen in rodent studies. Nobody knows yet if this happens in humans. Both drugs are contraindicated if you or a close family member has had medullary thyroid cancer. The same is true for Multiple Endocrine Neoplasia syndrome type 2.
Zepbound® and Mounjaro® both contain tirzepatide, made by Eli Lilly. Mounjaro® is approved for type 2 diabetes. Zepbound® is approved for chronic weight management and, since December 2024, for moderate-to-severe sleep apnea with obesity. This article compares Zepbound® to Wegovy®, both approved specifically for weight loss.
Yes. The FDA approved a once-daily Wegovy® pill in December 2025, and it launched in US pharmacies in January 2026. It comes in four doses and uses the same semaglutide as the injection. In its trial, people who stayed on it the full 64 weeks lost 16.6% of body weight.
If raw weight loss is your main goal and needles do not bother you, ask about Zepbound® first, based on the SURMOUNT-5 numbers. If you have heart disease alongside your weight, ask about Wegovy® for its cardiovascular data. If needles are the dealbreaker, ask about the new Wegovy® pill
KEEP READING
See who actually prescribes these medications
Wegovy® and Zepbound® both require a prescription. Compare licensed telehealth providers on intake speed, insurance support, and follow-up care, so you know where to start.
→ /compare/best-glp-1-providers/
SOURCES
1. Wilding JPH et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). NEJM 2021;384(11):989 to 1002. https://doi.org/10.1056/NEJMoa2032183
2. Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). NEJM 2022;387:205 to 216. https://doi.org/10.1056/NEJMoa2206038
3. Aronne LJ et al. Tirzepatide Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5). NEJM 2025. https://doi.org/10.1056/NEJMoa2416394
4. Lincoff AM et al. Semaglutide and Cardiovascular Outcomes in Obesity (SELECT). NEJM 2023;389:2221 to 2232. https://doi.org/10.1056/NEJMoa2307563
5. US Food and Drug Administration. WEGOVY (semaglutide) injection, prescribing information. Revised August 2025. https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/215256s024lbl.pdf
6. US Food and Drug Administration. ZEPBOUND (tirzepatide) injection, prescribing information. https://www.accessdata.fda.gov/drugsatfda_docs/label/2024/217806s003lbl.pdf
7. US Food and Drug Administration / Novo Nordisk. FDA approves Novo Nordisk’s Wegovy pill, the first and only oral GLP-1 for weight loss in adults. December 22, 2025.
8. US Food and Drug Administration. FDA approves first medication for obstructive sleep apnea. December 20, 2024.
9. US Food and Drug Administration / Novo Nordisk. FDA approval for Wegovy to treat adults with obesity. June 4, 2021.
Last updated: 2026-07-09 · Editorially reviewed by the Peptides.io team
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