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Zepbound vs Wegovy: Which Weight Loss Drug Is Better?

Regulatory status

Editorially reviewed · Last updated September 8, 2026 · How we review

Zepbound (tirzepatide) and Wegovy (semaglutide) are the two leading FDA-approved prescription weight loss drugs. Both have once-weekly injectable forms, and Wegovy also comes as a daily tablet. They work through different mechanisms — Zepbound targets two receptors (GLP-1 + GIP) while Wegovy targets one (GLP-1 only). In a head-to-head clinical trial (SURMOUNT-5), Zepbound produced significantly more weight loss than Wegovy.
This comparison focuses on the weight-management brands and their product choices. For molecule-level evidence across diabetes and weight management, read tirzepatide vs semaglutide. Approval and coverage depend on the exact product and indication.

At a glance — how do they differ?

Zepbound (Tirzepatide)Wegovy (Semaglutide)
ManufacturerEli LillyNovo Nordisk
Generic nameTirzepatideSemaglutide
MechanismDual agonist: GLP-1 + GIPSingle agonist: GLP-1 only
FDA approved forChronic weight management (2023)Chronic weight management (2021)
Max dose15 mg weekly7.2 mg weekly (Wegovy HD); SURMOUNT-5 tested up to 2.4 mg
Separate pivotal-trial mean-20.9% at 72 weeks (SURMOUNT-1)-14.9% at 68 weeks (STEP 1)
Head-to-head result-20.2% (SURMOUNT-5)-13.7% (SURMOUNT-5)
CV outcomes dataSURPASS-CVOT completed in T2D; Mounjaro CV indication approved Aug 2026Proven 20% MACE reduction (SELECT)
Oral optionNoYes (Wegovy tablet, approved 2025)

How do the mechanisms differ?

Zepbound: GLP-1 + GIP (Dual Agonist)

Zepbound activates two gut hormone receptors simultaneously. GLP-1 (glucagon-like peptide-1) reduces appetite and slows gastric emptying. GIP (glucose-dependent insulinotropic polypeptide) enhances glucose-dependent insulin secretion. The clinical comparison tests tirzepatide as a medicine; it does not isolate how much weight loss each receptor causes.

Wegovy: GLP-1 Only (Single Agonist)

Wegovy is a long-acting GLP-1 receptor agonist. It reduces appetite through brain signaling, slows gastric emptying to keep you fuller longer, and improves insulin sensitivity. Its weight-management evidence includes STEP trials and the SELECT cardiovascular outcomes trial.

Why the Difference Matters

SURMOUNT-5 found 6.5 percentage points greater average weight loss with tirzepatide at the doses tested. That does not establish the contribution of GIP alone. SELECT provides cardiovascular evidence for semaglutide in people with established cardiovascular disease and overweight or obesity without diabetes. The completed tirzepatide cardiovascular trial studied a different population with type 2 diabetes.

SURMOUNT-5 — which one lost more?

The SURMOUNT-5 Head-to-Head Trial

SURMOUNT-5 is the only randomized head-to-head trial directly comparing tirzepatide and semaglutide for weight loss. Published in 2025, this open-label trial enrolled 751 adults with obesity or overweight without diabetes. It compared maximum tolerated tirzepatide 10 or 15 mg with semaglutide 1.7 or 2.4 mg. It did not test Wegovy HD 7.2 mg or oral Wegovy.
OutcomeTirzepatide (Zepbound)Semaglutide (Wegovy)
Weight loss at 72 weeks-20.2%-13.7%
Absolute difference6.5 percentage points more—
Lost at least 10%81.6%60.5%
Lost at least 15%64.6%40.1%
Lost at least 20%48.4%27.3%
Lost at least 25%31.6%16.1%

Individual Trial Results

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DrugTrialDurationWeight Loss
Zepbound (tirzepatide)SURMOUNT-172 weeks-20.9% (15 mg)
Zepbound (tirzepatide)SURMOUNT-572 weeks-20.2%
Wegovy (semaglutide)STEP 168 weeks-14.9%
Wegovy (semaglutide)SURMOUNT-572 weeks-13.7%

The SURMOUNT-5 table uses the treatment-regimen estimand, which accounts for discontinuation. At least 25% weight loss occurred in 31.6% with tirzepatide and 16.1% with semaglutide. Results from SURMOUNT-1 and STEP 1 are separate-trial context, not additional head-to-head evidence.

How do the side effects compare?

Both drugs share GLP-1-class gastrointestinal side effects, which are the most common reason patients discontinue treatment.

Side EffectZepbound (SURMOUNT-5)Wegovy (SURMOUNT-5)
Nausea43.6%44.4%
Diarrhea23.5%23.4%
Vomiting15.0%21.3%
Constipation27.0%28.5%
Discontinuation due to AEs6.1%8.0%
SeverityMostly mild-moderateMostly mild-moderate

In SURMOUNT-5, gastrointestinal events were generally mild to moderate. Nausea rates were similar; vomiting and discontinuation due to adverse events were numerically higher with Wegovy at the doses studied. This does not predict individual tolerability.

Cost — what does insurance cover?

Costs depend on the dose, device, insurance plan and savings-program eligibility. Compare the maintenance price as well as any starter offer using Zepbound’s current savings terms and Wegovy’s manufacturer coverage information. Ask your insurer about prior authorization and the cost after meeting your deductible.
The Medicare GLP-1 Bridge launched July 1, 2026. Eligible beneficiaries pay $50 per month for included drugs: Wegovy injection or tablets, Foundayo tablets, and Zepbound KwikPen only. Zepbound single-dose pens and vials are excluded from this program. Coverage is conditional, not automatic.

Where Does Retatrutide Fit?

Retatrutide remains investigational. Lilly reported 28.7% mean weight loss at 68 weeks with 12 mg in TRIUMPH-4, which enrolled adults with obesity or overweight and knee osteoarthritis without diabetes. That is the efficacy estimand; the estimate regardless of treatment adherence was 23.7%. This placebo-controlled trial cannot establish superiority over tirzepatide or semaglutide. There is no confirmed FDA approval date.
See Retatrutide vs Tirzepatide and Retatrutide vs Wegovy.

Frequently Asked Questions

Is Zepbound better than Wegovy for weight loss?

In the SURMOUNT-5 head-to-head trial, Zepbound produced significantly more weight loss than Wegovy (-20.2% vs -13.7% at 72 weeks). However, "better" depends on individual factors including insurance coverage, cardiovascular risk (Wegovy has proven CV protection), and whether you prefer an oral option (available for Wegovy).

How much does Zepbound cost compared to Wegovy?

There is no single price comparison that applies to everyone. Check the exact dose and device, insurance copay, and current manufacturer savings terms. Eligible Medicare GLP-1 Bridge participants pay $50 per month for covered products; Zepbound coverage in that program is limited to KwikPen.

Do Zepbound and Wegovy have the same side effects?

Both can cause nausea, diarrhea, vomiting and constipation. In SURMOUNT-5, nausea rates were similar, while vomiting and adverse-event discontinuation were numerically higher with Wegovy at the studied doses. Individual responses vary.

Can I switch from Wegovy to Zepbound?

Switching is possible under medical supervision. Your doctor will determine the appropriate starting dose of Zepbound based on your current Wegovy dose and how well you tolerate it. There is no standardized switching protocol — decisions are made on a case-by-case basis.

Does Wegovy come in a pill form?

Yes. The FDA approved oral Wegovy (semaglutide tablets) in 2025 for chronic weight management. It is the first oral GLP-1 drug specifically approved for weight loss. Zepbound does not have an oral formulation.

Which has better cardiovascular protection — Zepbound or Wegovy?

The studies answer different questions. SELECT showed a 20% reduction in major cardiovascular events with semaglutide versus placebo in adults with established cardiovascular disease and overweight or obesity without diabetes. SURPASS-CVOT found tirzepatide non-inferior to dulaglutide in type 2 diabetes with established cardiovascular disease. Mounjaro gained a cardiovascular indication in August 2026; that is a different labeled population from Wegovy’s SELECT population.

Sources

How we keep this honest
What this is
Educational information, not medical advice. It reports published research — it doesn’t recommend that you use, obtain, or supply anything.
Regulatory status
Zepbound and Wegovy are FDA-approved medicines with product-specific indications. Retatrutide remains investigational.
Our standard
Every claim traces to a primary source. We label the strength of evidence and flag estimates as estimates — never as clinical fact.
No commercial ties
We don’t sell, supply, or link to suppliers of any medicine, and aren’t affiliated with any manufacturer.

Do not make decisions about your health without consulting a qualified healthcare provider. For trial enrolment, see ClinicalTrials.gov. More on how we review.

Grounded in primary sources
NEJMThe LancetJAMAFDAClinicalTrials.gov

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