Key Takeaways
- Wegovy is semaglutide, a GLP-1 receptor agonist. Zepbound is tirzepatide, which acts on two gut hormones (GLP-1 and GIP). Both are once-weekly injections FDA-approved for chronic weight management.
- In SURMOUNT-5, the first head-to-head trial, tirzepatide produced greater average weight loss than semaglutide — roughly 20% versus 14% of body weight over 72 weeks.
- The choice is not only about pounds. Wegovy carries an FDA-approved indication to reduce cardiovascular risk; Zepbound is the first drug approved to treat obstructive sleep apnea in adults with obesity.
- Insurance coverage, cost, dosing tolerance, and your other health conditions often decide the question more than the trial average does.
- This is general education, not a recommendation. The right medication — if any — is a decision for you and a clinician who knows your history.
The quick answer
If the only question is which drug tends to take off more weight, the current evidence points to Zepbound (tirzepatide). In a direct comparison, it outperformed Wegovy (semaglutide) on average. But “more weight loss on average” is not the same as “the right drug for you.” Wegovy has a heart-protection indication that Zepbound lacks, the two are priced and covered differently, and plenty of people reach their goals on either one. Read on for where each pulls ahead.
At a glance
| Wegovy | Zepbound | |
|---|---|---|
| Active drug | Semaglutide | Tirzepatide |
| How it works | GLP-1 receptor agonist | Dual GIP + GLP-1 receptor agonist |
| Also sold as | Ozempic (diabetes) | Mounjaro (diabetes) |
| FDA-approved for | Chronic weight management; reducing cardiovascular risk in adults with known heart disease plus obesity or overweight | Chronic weight management; moderate-to-severe obstructive sleep apnea in adults with obesity |
| Dosing | Once-weekly injection, titrated to 2.4 mg | Once-weekly injection, titrated to 10 or 15 mg |
| Average weight loss (head-to-head) | ~13.7% at 72 weeks | ~20.2% at 72 weeks |
| Most common side effects | Nausea, diarrhea, vomiting, constipation | Nausea, diarrhea, vomiting, constipation |
| Boxed warning | Thyroid C-cell tumor risk (seen in rodents) | Thyroid C-cell tumor risk (seen in rodents) |
Details and sources for each row are below. Approved uses and dosing come from the FDA prescribing information for Wegovy and Zepbound.
How they work — and why it matters
Both drugs mimic GLP-1, a hormone your gut releases after eating. GLP-1 slows how fast the stomach empties and signals fullness to the brain, so you feel satisfied on less food. That shared mechanism is why the two feel similar day-to-day and share the same core side effects.
The difference is that tirzepatide (Zepbound) also activates the GIP receptor — a second incretin hormone. The prevailing hypothesis is that hitting two pathways rather than one is part of why tirzepatide tends to drive more weight loss. Semaglutide (Wegovy) is a single-pathway GLP-1 drug. For a deeper look at each molecule, see our full profiles of semaglutide and tirzepatide.
Weight loss: what the head-to-head trial found
Until recently, comparing Wegovy and Zepbound meant comparing separate trials with different participants — an unreliable exercise. That changed with SURMOUNT-5, a randomized, open-label trial that put the two drugs directly against each other in 751 adults with obesity but without diabetes, at their maximum tolerated doses, over 72 weeks.
The result: participants on tirzepatide lost about 20.2% of their body weight, versus about 13.7% on semaglutide. Tirzepatide also produced larger reductions in waist circumference and several cardiometabolic markers. Notably, gastrointestinal side effects severe enough to stop treatment were somewhat less frequent with tirzepatide (about 2.7%) than semaglutide (about 5.6%).
Two honest caveats. First, the trial was open-label — participants knew which drug they were taking — which can nudge results. Second, a trial average is not a personal guarantee: some people lose more on semaglutide than the average person does on tirzepatide. The trial tells you the tendency, not your outcome.
Approved uses beyond weight: where each pulls ahead
This is where “which is better” stops being about a single number.
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Wegovy has an FDA-approved cardiovascular indication. It is approved to reduce the risk of major cardiovascular events — heart attack, stroke, cardiovascular death — in adults with established heart disease who also have obesity or overweight. If protecting your heart is part of the goal, that approved indication is a real point in Wegovy’s favor.
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Zepbound is approved to treat obstructive sleep apnea. In December 2024 it became the first medication FDA-approved for moderate-to-severe obstructive sleep apnea in adults with obesity, based on the SURMOUNT-OSA trial. For someone whose obesity and sleep apnea travel together, that is a meaningful edge.
Same drug class, two different second acts. The one that matches your other conditions may matter more than the weight-loss gap.
Side effects and safety
The side-effect profiles are close. For both drugs, the common complaints are gastrointestinal — nausea, diarrhea, vomiting, constipation — and they tend to be worst during dose increases, then ease. Slow titration exists specifically to blunt them.
Both medications also carry a boxed warning about a risk of thyroid C-cell tumors observed in rodent studies; both are contraindicated in people with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2. Both can cause more serious effects such as pancreatitis and gallbladder problems, which is part of why they require a prescriber’s oversight.
One issue that applies to both: a meaningful share of the weight lost on any GLP-1 drug can be lean muscle, not just fat — one reason reviews of incretin therapy emphasize adequate protein and resistance training alongside the medication. See our guides on nutrition and exercise for how to protect muscle while you lose weight.
Cost, coverage, and access
For many people this is the deciding factor. Both are expensive without insurance, and coverage is inconsistent — some plans cover one, the other, or neither, and prior authorization is common. Manufacturer savings programs exist but eligibility varies. Because coverage shifts frequently, the practical question is often not “which drug is best?” but “which drug can I actually get and afford?” That is worth confirming with your prescriber and pharmacy before you settle on either.
A caution on the cheaper “compounded” versions advertised online: the FDA declared the semaglutide and tirzepatide shortages resolved, and routine compounding of copies is no longer permitted. We cover what that means in our guide to compounded semaglutide’s legal status.
So which should you choose?
There is no single winner — there is a best fit.
- Leaning Zepbound (tirzepatide): you want the greatest likelihood of larger weight loss, you have obstructive sleep apnea, or you did not tolerate or respond well to semaglutide.
- Leaning Wegovy (semaglutide): you have established cardiovascular disease and want the approved heart-protection benefit, it is the drug your insurance covers, or you have already responded well to it.
Whichever way you lean, the decision belongs in a clinic. Bring your weight history, your other conditions, and your coverage details, and let a clinician help you weigh them. Read how we source and review this content in our editorial policy.