Wegovy vs. Zepbound: Which GLP-1 Weight Loss Drug Is More Effective?

The Short Answer

Wegovy and Zepbound are both FDA-approved injectable medications for chronic weight management, but they work through different mechanisms and produce different amounts of weight loss. Zepbound (tirzepatide) produces approximately 47% more weight loss than Wegovy (semaglutide) based on head-to-head data from the SURMOUNT-5 trial published in the New England Journal of Medicine in 2025. However, Wegovy has a longer track record, more cardiovascular outcomes data, and may be preferred for patients with a history of heart disease.

What Are Wegovy and Zepbound?

Wegovy (semaglutide 2.4 mg) is a once-weekly injectable GLP-1 receptor agonist approved by the FDA in June 2021 for chronic weight management in adults with obesity (BMI ≥30) or overweight (BMI ≥27) with at least one weight-related condition. It is manufactured by Novo Nordisk — the same company that makes Ozempic (semaglutide 1 mg for type 2 diabetes).

Zepbound (tirzepatide) is a once-weekly injectable dual GIP/GLP-1 receptor agonist approved by the FDA in November 2023 for chronic weight management. It is manufactured by Eli Lilly — the same company that makes Mounjaro (tirzepatide for type 2 diabetes). Zepbound was also approved in December 2024 for moderate-to-severe obstructive sleep apnea in adults with obesity, making it the first medication approved for this indication.

Key distinction: Wegovy activates one receptor (GLP-1); Zepbound activates two receptors (GIP + GLP-1). This dual mechanism is believed to explain Zepbound's superior weight loss efficacy.

Wegovy vs. Zepbound: Side-by-Side Comparison

Weight Loss: How Do They Compare?

Individual Trial Results

Wegovy (STEP 1 trial, 2021):

• 1,961 adults with obesity or overweight + weight-related condition
• Average weight loss: 13.7% of body weight over 68 weeks
• 86.4% of participants lost ≥5% of body weight
• 69.1% lost ≥10%; 50.5% lost ≥15%

Zepbound (SURMOUNT-1 trial, 2022):

• 2,539 adults with obesity or overweight + weight-related condition
• Average weight loss at maximum dose (15 mg): 20.9% of body weight over 72 weeks
• 91% of participants lost ≥5% of body weight
• 79% lost ≥10%; 57% lost ≥15%; 36% lost ≥20%

Head-to-Head: SURMOUNT-5 Trial (NEJM, 2025)

The most important data point for this comparison comes from SURMOUNT-5, a randomized, open-label, head-to-head trial published in the New England Journal of Medicine in January 2025:

• 751 participants with obesity or overweight + weight-related condition (no type 2 diabetes)
• Duration: 72 weeks
• Results:
  • Zepbound (tirzepatide 10 or 15 mg): 20.2% average weight loss
  • Wegovy (semaglutide 2.4 mg): 13.7% average weight loss
  • Difference: 47% more weight loss with Zepbound (6.5 percentage points)
  • Zepbound participants were 2.5× more likely to achieve ≥25% weight loss

Bottom line from SURMOUNT-5: Tirzepatide (Zepbound) produces significantly more weight loss than semaglutide (Wegovy) in a direct head-to-head comparison. This is the highest level of evidence available for comparing these two medications.

Cardiovascular Benefits

Wegovy: SELECT Trial (2023)

Wegovy has the stronger cardiovascular evidence base. The SELECT trial (published in NEJM, 2023) enrolled 17,604 adults with established cardiovascular disease and obesity (no type 2 diabetes):

• 20% reduction in major adverse cardiovascular events (MACE: non-fatal MI, non-fatal stroke, cardiovascular death)
• This was the first weight loss medication to demonstrate a reduction in cardiovascular events in a dedicated outcomes trial
• Based on SELECT data, the FDA approved Wegovy in March 2024 to reduce the risk of serious cardiovascular events in adults with cardiovascular disease and obesity or overweight

Zepbound: No Dedicated CV Outcomes Trial Yet

Zepbound does not yet have a dedicated cardiovascular outcomes trial in patients without type 2 diabetes. However:

• The SURPASS-CVOT trial (ongoing) is evaluating tirzepatide's cardiovascular outcomes in patients with type 2 diabetes
• Mounjaro (tirzepatide for T2D) has shown cardiovascular risk reduction in diabetic patients
• Mechanistically, the dual GIP/GLP-1 mechanism may provide cardiovascular benefits, but this remains to be proven in a dedicated outcomes trial

Verdict: If you have established cardiovascular disease, Wegovy currently has stronger evidence for reducing cardiovascular risk.

Dosing Schedules

Wegovy Titration Schedule

Zepbound Titration Schedule

Both medications are administered as subcutaneous injections in the abdomen, thigh, or upper arm. The injection pen is pre-filled and designed for self-administration.

Side Effects: How Do They Compare?

Both Wegovy and Zepbound share a similar side effect profile because they both activate GLP-1 receptors. The most common side effects are gastrointestinal.

Key observations:

• Zepbound appears to have a slightly lower rate of nausea and vomiting than Wegovy, though direct comparisons are difficult due to different trial populations
• Both medications have a black box warning for thyroid C-cell tumors (based on rodent studies; human relevance is unknown)
• Both are contraindicated in patients with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2)
• Both can cause pancreatitis (rare but serious); discontinue if suspected

Cost and Insurance Coverage

List Prices (2025)

Zepbound's Cost Advantage: Single-Dose Vials

In May 2024, Eli Lilly launched Zepbound single-dose vials (SDVs) at significantly lower prices than the autoinjector pens:

• 2.5 mg vial: ~$399/month
• 5 mg vial: ~$549/month
• 7.5 mg, 10 mg, 12.5 mg, 15 mg vials: ~$549/month

These vials require a separate syringe for injection and are not eligible for Eli Lilly's savings card, but they represent a major cost reduction for cash-pay patients. Wegovy does not have an equivalent lower-cost option.

Insurance Coverage

• Commercial insurance: Both medications are covered by many commercial plans, but prior authorization is typically required. Coverage rates have been improving as evidence accumulates.
• Medicare: As of 2025, Medicare Part D covers Wegovy for cardiovascular risk reduction (based on SELECT trial data). Zepbound is not yet covered by Medicare for obesity alone.
• Medicaid: Coverage varies significantly by state for both medications.

Which Is Right for You? A Decision Framework

Choose Wegovy if:

• You have established cardiovascular disease (heart attack, stroke, or peripheral artery disease) — SELECT trial data supports CV risk reduction
• You have type 2 diabetes and your doctor prefers Ozempic (same drug, different dose) for glycemic control
• You prefer a medication with a longer track record (approved 2021 vs. 2023)
• Your insurance covers Wegovy but not Zepbound

Choose Zepbound if:

• Maximum weight loss is your primary goal — SURMOUNT-5 shows 47% more weight loss vs. Wegovy
• You have obstructive sleep apnea — Zepbound is the only medication FDA-approved for this indication
• You want to minimize cost — Zepbound SDVs start at ~$399/month vs. Wegovy's ~$1,349/month
• You have type 2 diabetes and your doctor prefers Mounjaro (same drug, different indication)
• You tried Wegovy and did not achieve adequate weight loss

Talk to Your Doctor if:

• You have a history of pancreatitis, gallbladder disease, or thyroid cancer
• You are pregnant or planning to become pregnant (both are contraindicated)
• You have severe gastrointestinal conditions (gastroparesis, inflammatory bowel disease)
• You are taking medications that affect blood sugar (insulin, sulfonylureas) — dose adjustments may be needed

Frequently Asked Questions

Q: Is Zepbound better than Wegovy? A: For weight loss, yes — Zepbound produces approximately 47% more weight loss than Wegovy in head-to-head trials (SURMOUNT-5). However, Wegovy has stronger cardiovascular outcomes data (SELECT trial) and may be preferred for patients with established heart disease.

Q: Can I switch from Wegovy to Zepbound? A: Yes, switching is possible under medical supervision. Your doctor will typically start you at a lower dose of Zepbound and titrate up. There is no required washout period between the two medications.

Q: Are Wegovy and Ozempic the same drug? A: Yes — both contain semaglutide, but at different doses. Ozempic (0.5–2 mg) is FDA-approved for type 2 diabetes; Wegovy (2.4 mg) is FDA-approved for weight management. The higher dose in Wegovy produces greater weight loss.

Q: Are Zepbound and Mounjaro the same drug? A: Yes — both contain tirzepatide. Mounjaro is FDA-approved for type 2 diabetes; Zepbound is FDA-approved for weight management and obstructive sleep apnea.

Q: How long do you have to take Wegovy or Zepbound? A: Both medications are intended for long-term use. Clinical trials show that most of the weight lost is regained within 1–2 years of stopping either medication. These are chronic disease treatments, not short-term solutions.

Q: Which has fewer side effects, Wegovy or Zepbound? A: Both have similar GI side effect profiles. Zepbound appears to have slightly lower rates of nausea and vomiting in clinical trials, but direct comparisons are difficult. Individual responses vary significantly.

The Bottom Line

Both Wegovy and Zepbound are highly effective medications for chronic weight management that represent a major advance over older weight loss drugs. The choice between them should be made with your healthcare provider based on your individual health history, weight loss goals, cardiovascular risk, and insurance coverage.

Always consult a qualified healthcare professional before starting, stopping, or changing any medication.