Zepbound vs Wegovy: Which Weight Loss Drug Is Better?
Zepbound (tirzepatide) and Wegovy (semaglutide) are the two leading FDA-approved prescription weight loss drugs. Both are once-weekly injections, but 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.
Side-by-Side Comparison
| Zepbound (Tirzepatide) | Wegovy (Semaglutide) | |
|---|---|---|
| Manufacturer | Eli Lilly | Novo Nordisk |
| Generic name | Tirzepatide | Semaglutide |
| Mechanism | Dual agonist: GLP-1 + GIP | Single agonist: GLP-1 only |
| FDA approved for | Chronic weight management (2023) | Chronic weight management (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Max weight loss | -22.5% 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 data | In progress (SURPASS-CVOT) | Proven 20% MACE reduction (SELECT) |
| Oral option | No | Yes (Wegovy tablet, approved 2025) |
| List price | ~$1,059/month | ~$1,349/month |
| Savings programs | LillyDirect (~$550/mo) | Novo savings card (varies) |
How 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 insulin secretion and may increase energy expenditure through effects on fat tissue. The combination produces additive weight loss beyond what either receptor achieves alone.
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. As the first major GLP-1 drug approved specifically for weight loss, it has the longest track record and the most safety data.
Why the Difference Matters
The addition of GIP receptor agonism in Zepbound appears to produce more weight loss — about 6-7 percentage points more in head-to-head comparison. However, Wegovy has proven cardiovascular protection from the SELECT trial (20% reduction in major cardiovascular events), which Zepbound does not yet have.
Weight Loss Comparison
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 2024, it enrolled 751 adults with obesity.
| Outcome | Tirzepatide (Zepbound) | Semaglutide (Wegovy) |
|---|---|---|
| Weight loss at 72 weeks | -20.2% | -13.7% |
| Absolute difference | 6.5 percentage points more | — |
| Lost at least 5% | 94% | 85% |
| Lost at least 10% | 82% | 66% |
| Lost at least 15% | 70% | 47% |
| Lost at least 20% | 55% | 28% |
| Lost at least 25% | 35% | 12% |
Individual Trial Results
| Drug | Trial | Duration | Weight Loss |
|---|---|---|---|
| Zepbound (tirzepatide) | SURMOUNT-1 | 72 weeks | -22.5% (15 mg) |
| Zepbound (tirzepatide) | SURMOUNT-5 | 72 weeks | -20.2% |
| Wegovy (semaglutide) | STEP 1 | 68 weeks | -14.9% |
| Wegovy (semaglutide) | SURMOUNT-5 | 72 weeks | -13.7% |
The head-to-head trial confirms what separate trials suggested: tirzepatide consistently produces more weight loss than semaglutide. Roughly twice as many Zepbound patients reached the 25% weight loss threshold compared to Wegovy (35% vs 12%).
Side Effects Comparison
Both drugs share GLP-1-class gastrointestinal side effects, which are the most common reason patients discontinue treatment.
| Side Effect | Zepbound (SURMOUNT-5) | Wegovy (SURMOUNT-5) |
|---|---|---|
| Any GI event | ~70% | ~65% |
| Nausea | 28% | 26% |
| Diarrhea | 22% | 18% |
| Vomiting | 13% | 10% |
| Constipation | 14% | 12% |
| Discontinuation due to AEs | ~5% | ~3% |
| Severity | Mostly mild-moderate | Mostly mild-moderate |
Side effect profiles are broadly similar. Both drugs cause nausea, diarrhea, vomiting, and constipation that are typically mild to moderate and tend to resolve during dose escalation. Zepbound has slightly higher rates overall, likely reflecting the greater metabolic effect.
Cost and Insurance
| Zepbound | Wegovy | |
|---|---|---|
| List price | ~$1,059/month | ~$1,349/month |
| Manufacturer savings | LillyDirect: ~$550/month | Novo savings card (varies by insurance) |
| Medicare coverage | Limited (mainly for diabetes as Mounjaro) | Expanding under AOM coverage provisions |
| Commercial insurance | Growing formulary coverage | Broader formulary coverage |
| Oral option cost | N/A | Wegovy tablet (similar pricing) |
Wegovy generally has broader insurance coverage due to its earlier approval and cardiovascular outcomes data. Zepbound has a more straightforward direct-to-consumer pricing model through LillyDirect. Both remain expensive without insurance or savings programs.
Where Does Retatrutide Fit?
Retatrutide is the first triple agonist — targeting GLP-1, GIP, and glucagon receptors. In Phase 3 trials, it produced 28.7% body weight loss, the largest result for any anti-obesity medication. It is not yet FDA-approved (expected 2027).
While Zepbound and Wegovy represent the current generation, retatrutide adds glucagon receptor agonism for increased energy expenditure and liver fat reduction. For more detail, see Retatrutide vs Zepbound 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?
Zepbound lists at approximately $1,059/month; Wegovy at approximately $1,349/month. Zepbound is available through LillyDirect at ~$550/month. Wegovy offers savings cards that vary by insurance status. Both are significantly less expensive through insurance when covered.
Do Zepbound and Wegovy have the same side effects?
Yes, both share the same GLP-1 class side effects: nausea, diarrhea, vomiting, and constipation. These are typically mild to moderate and tend to improve over time. Zepbound has slightly higher GI side effect rates in head-to-head comparison, but discontinuation rates are similar.
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?
Wegovy currently has the stronger cardiovascular evidence. The SELECT trial showed a 20% reduction in major adverse cardiovascular events (MACE). Tirzepatide's dedicated cardiovascular outcomes trial (SURPASS-CVOT) is still ongoing.
Sources
- Lilly. (2024). SURMOUNT-5 Results: Tirzepatide vs Semaglutide Head-to-Head. Press release.
- Jastreboff, A.M., et al. (2022). Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine. DOI: 10.1056/NEJMoa2206038
- Wilding, J.P.H., et al. (2021). Once-Weekly Semaglutide in Adults with Overweight or Obesity. New England Journal of Medicine. DOI: 10.1056/NEJMoa2032183
- Lincoff, A.M., et al. (2023). Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. New England Journal of Medicine. DOI: 10.1056/NEJMoa2307563
Medical Disclaimer
The content on glp3.wiki is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Both Zepbound and Wegovy are prescription medications — consult your healthcare provider to determine which is appropriate for you.
This site is not affiliated with Eli Lilly, Novo Nordisk, or any pharmaceutical manufacturer.
Related reading
Tirzepatide vs Semaglutide: Complete Comparison (2026 Data)
Tirzepatide vs semaglutide with SURMOUNT-5 head-to-head data: -20.2% vs -13.7% weight loss. Full comparison of efficacy, side effects, and access.
Retatrutide vs Zepbound: What's the Difference?
Same manufacturer, different drugs. Retatrutide adds glucagon agonism for 28.7% vs Zepbound's 22.5% weight loss.
Retatrutide vs Wegovy: Triple Agonist vs GLP-1
Retatrutide produces nearly double the weight loss of Wegovy, but Wegovy is available now with proven cardiovascular protection.