Wegovy vs. Zepbound: A Head-to-Head Comparison for 2025

Two drugs now dominate the weight loss conversation: Wegovy (semaglutide 2.4mg, by Novo Nordisk) and Zepbound (tirzepatide, by Eli Lilly). Both are FDA-approved for chronic weight management. Both work by targeting GLP-1 receptors. And both produce weight loss results that were, until recently, only achievable through bariatric surgery.

So which is better? The answer is more nuanced than most headlines suggest. Here is an evidence-based comparison of both drugs — covering mechanism, efficacy, side effects, cost, and who each one is most appropriate for.

How Each Drug Works

Wegovy (Semaglutide): Single GLP-1 Agonist

Semaglutide mimics glucagon-like peptide-1 (GLP-1), a hormone released by the gut after eating. GLP-1 signals the hypothalamus to reduce appetite, slows gastric emptying to prolong satiety, and helps regulate blood sugar by stimulating insulin release. Wegovy is dosed at 2.4mg once weekly via subcutaneous injection, titrated up over 16–20 weeks from an initial 0.25mg starting dose.

Zepbound (Tirzepatide): Dual GLP-1 / GIP Agonist

Tirzepatide is a dual incretin agonist — it activates both GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) receptors simultaneously. GIP is another gut hormone that independently regulates appetite and fat storage. The combined action of both pathways appears to produce synergistic weight loss effects that exceed either pathway alone. Zepbound is dosed weekly at 2.5mg, 5mg, 10mg, or 15mg, titrated over 20 weeks.

Clinical Trial Data: STEP vs. SURMOUNT

The most important data for comparing these drugs comes from their respective phase 3 weight management trials.

STEP 1 Trial (Semaglutide / Wegovy)

Published in the New England Journal of Medicine (2021), the STEP 1 trial randomized 1,961 adults with obesity (BMI ≥30, or ≥27 with a weight-related comorbidity) to semaglutide 2.4mg or placebo for 68 weeks. Results:

• Average weight loss: 14.9% of body weight (vs. 2.4% with placebo)
• Percentage of participants losing ≥10% of body weight: 69.1%
• Percentage losing ≥20% of body weight: 32.0%

SURMOUNT-1 Trial (Tirzepatide / Zepbound)

Published in the New England Journal of Medicine (2022), SURMOUNT-1 randomized 2,539 adults with obesity to tirzepatide (5mg, 10mg, or 15mg) or placebo for 72 weeks. Results at the highest dose (15mg):

• Average weight loss: 20.9% of body weight (vs. 3.1% with placebo)
• Percentage losing ≥10% of body weight: 91.0%
• Percentage losing ≥20% of body weight: 57.0%

The difference is meaningful: tirzepatide at its highest dose produces roughly 40% more weight loss than semaglutide at its highest dose. Both are far superior to placebo and to previous obesity medications, but if maximum weight loss is the primary goal, the data clearly favors tirzepatide.

It's important to note these are separate trials with different patient populations, trial durations, and protocols — making direct comparison imperfect. A head-to-head trial (SURPASS-CVOT vs. SELECT) doesn't directly compare weight loss as a primary endpoint, and the SURMOUNT trials weren't designed to be compared directly to STEP. However, the magnitude of difference is large enough that most obesity medicine specialists consider tirzepatide more potent for weight loss.

Side Effect Comparison

Both drugs share a similar GI-focused side effect profile, which is expected given their shared GLP-1 mechanism. The most common adverse effects are:

• Nausea (most common, especially during dose escalation): ~40–45% with tirzepatide; ~44% with semaglutide
• Diarrhea: ~23% tirzepatide; ~30% semaglutide
• Constipation: ~24% tirzepatide; ~24% semaglutide
• Vomiting: ~20% tirzepatide; ~24% semaglutide

GI side effects are most pronounced during the first 4–8 weeks as doses increase. The slow titration protocol for both drugs is specifically designed to minimize these symptoms. Most patients find side effects manageable and significantly reduced by month 3.

Both drugs carry black-box warnings regarding thyroid C-cell tumors (based on rodent studies; not confirmed in humans) and are contraindicated in patients with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2. Neither should be used during pregnancy.

Cost Comparison

One of the biggest practical considerations — and one that affects millions of patients — is cost.

• Wegovy (brand): ~$1,349/month list price; limited insurance coverage for obesity indication
• Zepbound (brand): ~$1,060/month list price; similarly limited coverage
• Compounded semaglutide: $199–$349/month via telehealth providers
• Compounded tirzepatide: $249–$399/month via telehealth providers

For the majority of patients without insurance covering obesity medications, the brand-name options are simply unaffordable for sustained use. Compounded versions of both drugs are available through telehealth providers at a fraction of the cost, using the same active ingredients sourced from FDA-registered 503B compounding facilities.

Who Each Drug Is Best For

Consider Wegovy (or compounded semaglutide) if:

• You want a well-studied, FDA-approved weight loss medication with the longest track record
• Your insurance covers semaglutide
• You've previously done well on a once-weekly injection and want to try GLP-1 therapy
• You have a strong cardiovascular risk profile (semaglutide's SELECT trial showed 20% reduction in major cardiac events)

Consider Zepbound (or compounded tirzepatide) if:

• Maximum weight loss is your primary goal
• You have significant insulin resistance or pre-diabetes alongside obesity
• You've previously used semaglutide and plateaued before reaching your target weight
• You want the most powerful currently-available GLP-1 based therapy

Wegovy vs. Zepbound: Head-to-Head Comparison

Which Does Truventa Offer — and Which Should You Choose?

At Truventa Medical, we prescribe both compounded semaglutide and compounded tirzepatide — the same active ingredients as Wegovy and Zepbound, respectively, sourced from FDA-registered 503B compounding facilities.

Our physicians work with you to determine which is more appropriate based on your health history, BMI, metabolic profile, and goals. For most patients starting out, compounded semaglutide is an excellent first step — excellent efficacy, a strong safety track record, and the lowest cost entry point. For patients who want maximum weight loss potential from the start, or who have previously used semaglutide without reaching their goals, compounded tirzepatide is the stronger choice.

Either way, you receive physician oversight, ongoing monitoring, and dose optimization throughout your treatment — all online, starting with a free health intake.