Wegovy vs. Mounjaro: Which Is Better for Weight Loss?

Two injectable medications — Wegovy (semaglutide) and Mounjaro (tirzepatide) — have fundamentally changed the conversation around obesity treatment. Both belong to the GLP-1 receptor agonist class, but their mechanisms, clinical results, and ideal candidates differ in meaningful ways. If you're deciding between them, here's what the science actually says.

How They Work: GLP-1 vs. Dual Agonism

Understanding the difference between Wegovy and Mounjaro starts with their mechanisms of action:

Wegovy (semaglutide) is a GLP-1 receptor agonist. GLP-1 (glucagon-like peptide-1) is a hormone released after eating that signals fullness, slows gastric emptying, and reduces appetite by acting on the hypothalamus. Semaglutide mimics this hormone at a much higher concentration and longer duration than the body naturally produces, leading to sustained appetite suppression and reduced caloric intake.

Mounjaro (tirzepatide) is a dual GIP/GLP-1 receptor agonist — the first of its kind. In addition to activating GLP-1 receptors, it also activates GIP (glucose-dependent insulinotropic polypeptide) receptors. GIP works synergistically with GLP-1 to enhance insulin secretion, reduce glucagon, and may play an additional role in energy storage and fat metabolism. This dual action is believed to be why tirzepatide produces greater weight loss in clinical trials than semaglutide alone.

Clinical Trial Data: STEP vs. SURMOUNT

The head-to-head comparison starts with the landmark trials behind each drug:

STEP 1 (Semaglutide/Wegovy): In the STEP 1 trial published in the New England Journal of Medicine (2021), adults with obesity who received semaglutide 2.4 mg weekly lost an average of 14.9% of body weight over 68 weeks, compared to 2.4% in the placebo group. Over two-thirds of participants lost more than 10% of their body weight.

SURMOUNT-1 (Tirzepatide/Mounjaro): In the SURMOUNT-1 trial (NEJM, 2022), adults with obesity receiving the highest dose of tirzepatide (15 mg weekly) lost an average of 20.9% of body weight over 72 weeks — the most robust weight loss ever seen in a Phase 3 pharmacological trial at the time. Even the lowest studied dose (5 mg) produced ~15% weight loss.

Important caveat: these trials used different populations, durations, and study designs, so direct comparisons must be made cautiously. However, the SURMOUNT data consistently outpaces STEP at comparable doses, and the recently published SURMOUNT-5 trial — which directly compared tirzepatide to semaglutide — confirmed tirzepatide's advantage, with participants losing approximately 47% more weight on tirzepatide versus semaglutide.

Side Effect Profiles: What to Expect

Both medications share a similar GI side effect profile because of their shared GLP-1 mechanism. The most common adverse effects for both include:

• Nausea (most common, especially during dose escalation)
• Vomiting
• Diarrhea or constipation
• Decreased appetite
• Fatigue during initial weeks

In the STEP and SURMOUNT trials, GI side effects were reported in 60–80% of participants but were primarily mild-to-moderate and decreased over time. Discontinuation rates due to adverse events were approximately 7% for semaglutide and 4–8% for tirzepatide depending on dose.

A rare but serious risk for both: medullary thyroid carcinoma (observed in rodent studies; contraindicated in patients with personal/family history of MTC or MEN2 syndrome). Neither medication should be used during pregnancy. Pancreatitis is a rare risk that warrants monitoring.

Some patients report that tirzepatide produces less nausea compared to semaglutide, though this varies by individual and dose escalation schedule.

FDA Approvals and Indications

Both drugs are FDA-approved, but for slightly different primary indications:

• Wegovy: FDA-approved in June 2021 specifically for chronic weight management in adults with obesity (BMI ≥30) or overweight (BMI ≥27) with at least one weight-related condition. Also carries FDA approval for reducing cardiovascular risk in adults with obesity and established heart disease (SELECT trial, 2023).
• Mounjaro: Originally FDA-approved in May 2022 for type 2 diabetes. Its weight-loss brand, Zepbound (same tirzepatide molecule), received FDA approval for chronic weight management in November 2023.

Physicians can prescribe Mounjaro (the diabetes brand) off-label for weight loss, which is common. Zepbound is the "on-label" weight loss approval. From a pharmacological standpoint, they are identical.

Cost and Insurance Coverage

Cost remains one of the most significant barriers to GLP-1 access:

• Wegovy list price: ~$1,350/month without insurance
• Zepbound/Mounjaro list price: ~$1,060–$1,350/month without insurance

Insurance coverage is inconsistent. Many commercial plans now cover these medications with prior authorization, while Medicare Part D coverage for obesity medications remains limited (though the TREAT Act is pushing for change). Manufacturer savings cards (Novo Nordisk for Wegovy; Eli Lilly for Mounjaro/Zepbound) can reduce out-of-pocket costs to as low as $25/month for eligible commercially-insured patients.

Compounded semaglutide and tirzepatide have become alternatives during shortage periods, typically costing $100–$400/month through licensed telehealth providers, making treatment accessible to far more patients.

Which Should You Choose?

There's no single "better" medication — the right choice depends on your individual profile:

• Choose Wegovy (semaglutide) if: you have established cardiovascular disease (SELECT trial supports cardiovascular risk reduction), you've had good prior response to GLP-1 medications, or your insurance covers it specifically.
• Choose Mounjaro/Zepbound (tirzepatide) if: you want the highest average weight loss outcomes supported by current data, you also have type 2 diabetes (tirzepatide provides outstanding glycemic control), or you've tried semaglutide with suboptimal results.
• In either case: A licensed physician should guide the decision based on your full medical history, comorbidities, medication tolerability, and weight loss goals.

The Role of Telehealth in Accessing GLP-1 Medications

Historically, getting a prescription for weight loss medications required a specialist visit — often with a 3–6 month waitlist. Telehealth has removed that barrier entirely. Through platforms like Truventa Medical, you can complete a clinical evaluation, receive a prescription if appropriate, and have medication shipped directly to you — all without leaving home.

Our physicians evaluate each patient individually, review labs and medical history, and recommend the most appropriate treatment for your situation. We also offer compounded semaglutide and tirzepatide options at significantly lower price points when brand-name medications aren't accessible.