Head-to-head data from the SURMOUNT-5 trial showed tirzepatide producing an average of 20.2 percent body weight loss versus 13.7 percent for semaglutide over 72 weeks — the first direct clinical comparison of the two most prescribed GLP-1 class weight-loss drugs. The Wegovy vs Mounjaro decision, however, involves more than raw weight loss numbers. The two drugs have different FDA indications, different mechanisms, different side effect profiles, different pricing, and different insurance coverage patterns. This guide walks through what actually separates them and how to think about which makes sense for your situation. Start with our medical conditions guide for context.
First, Are They Actually Comparable Drugs?
Technically, Wegovy and Mounjaro are not directly comparable because they are approved for different indications. Wegovy (semaglutide 2.4 mg weekly) is FDA-approved for chronic weight management in adults with obesity. Mounjaro (tirzepatide) is FDA-approved for type 2 diabetes. The direct weight-loss comparison between the two underlying molecules is Wegovy versus Zepbound, which contains the same tirzepatide as Mounjaro but is approved for weight management.
In practice, patients and prescribers often compare Wegovy and Mounjaro side by side because both are commonly used (sometimes off-label) for weight loss, and both are covered differently by insurance. When physicians describe “Wegovy vs Mounjaro,” they typically mean the broader semaglutide-vs-tirzepatide question. For the on-label comparison, see our Zepbound for weight loss guide.
Mechanism Differences
Wegovy contains semaglutide, which activates the glucagon-like peptide-1 (GLP-1) receptor. When activated, GLP-1 signaling slows gastric emptying, reduces appetite through brain pathways, and enhances glucose-dependent insulin secretion. Semaglutide is a single-agonist drug hitting just the GLP-1 receptor.
Mounjaro contains tirzepatide, which activates two hormone receptors simultaneously: GLP-1 and glucose-dependent insulinotropic polypeptide (GIP). GIP works in parallel with GLP-1 to influence glucose metabolism and appetite, and its co-activation appears to produce additive weight-loss effects. This dual mechanism is what the trial data suggests gives tirzepatide its edge over semaglutide on pure weight-loss outcomes.
Weight Loss: SURMOUNT-5 and Other Data
The SURMOUNT-5 head-to-head trial, reported in 2024, enrolled 751 adults with obesity and without diabetes and randomized them to either maximum-dose tirzepatide or maximum-dose semaglutide for 72 weeks. Tirzepatide produced an average weight loss of 20.2 percent compared to 13.7 percent for semaglutide, a statistically significant difference of approximately 6 percentage points in favor of tirzepatide.
These results align with indirect comparisons from the STEP and SURMOUNT programs. STEP-1 showed semaglutide 2.4 mg producing 14.9 percent weight loss over 68 weeks. SURMOUNT-1 showed tirzepatide 15 mg producing 22.5 percent over 72 weeks. Across both direct and indirect data, tirzepatide consistently outperforms semaglutide on weight-loss outcomes in the obesity population.
Side Effect Profiles
Both drugs share the common GLP-1 class side effects: nausea, vomiting, diarrhea, constipation, abdominal pain, and indigestion. Nausea affects roughly 30 to 45 percent of patients during titration on either drug, typically improving within weeks as tolerance develops. Injection site reactions are uncommon but possible with either.
Published data and real-world experience suggest tirzepatide’s side effect profile may be slightly more intense on average at maximum doses, likely because the absolute weight loss is greater. Both carry the same boxed warning for medullary thyroid carcinoma based on rodent studies. Rare but serious risks include pancreatitis, gallbladder disease, and acute kidney injury from severe dehydration. For details see our tirzepatide side effects article.
Dosing and Titration
Wegovy starts at 0.25 mg weekly for four weeks, then increases every four weeks through 0.5 mg, 1.0 mg, 1.7 mg, and finally 2.4 mg weekly for maintenance. Full titration takes about 16 to 20 weeks. Injections are given once weekly in the abdomen, thigh, or upper arm.
Mounjaro starts at 2.5 mg weekly for four weeks, then titrates through 5 mg, 7.5 mg, 10 mg, 12.5 mg, up to a maximum of 15 mg weekly. Titration can proceed every four weeks as tolerated, though many patients find maintenance at 5 mg or 10 mg sufficient without reaching the maximum. For dose schedules see our Wegovy doses article.
Cost and Insurance Coverage
Both drugs sit near the top of retail drug prices. Wegovy lists at roughly $1,349 per month, Mounjaro at roughly $1,080 per month, at 2026 wholesale acquisition prices. Commercial insurance coverage for Wegovy is generally tied to weight-loss indications, while Mounjaro coverage is generally tied to type 2 diabetes indications.
Manufacturer savings programs reduce costs substantially for eligible commercially insured patients. The Novo Nordisk Wegovy savings card can bring copays to as low as $0 for commercial plan holders with coverage. The Lilly Mounjaro savings card can bring copays to as low as $25 for type 2 diabetes patients with commercial coverage. Neither program applies to Medicare, Medicaid, or other federal beneficiaries. See our Wegovy cost guide and Mounjaro price breakdown.
Which Drug for Which Patient
For a patient with type 2 diabetes seeking glucose control plus some weight loss, Mounjaro is the on-label choice and typically produces strong A1C reduction plus modest-to-significant weight loss. For a patient with obesity without diabetes seeking maximum weight loss, Wegovy is the on-label option, with Zepbound (same tirzepatide as Mounjaro) as the on-label tirzepatide alternative producing greater average weight loss.
Prescribers often choose based on insurance coverage (whichever is covered wins in many cases), patient tolerability history with GLP-1 drugs, and individual response. Patients who have struggled with semaglutide side effects may tolerate tirzepatide differently (or vice versa), and switching between the two is clinically common.
Frequently Asked Questions
Which loses more weight, Wegovy or Mounjaro?
In direct head-to-head data from SURMOUNT-5, tirzepatide (the molecule in Mounjaro and Zepbound) produced 20.2 percent average weight loss versus 13.7 percent for semaglutide (Wegovy) over 72 weeks. Individual results vary, but tirzepatide consistently produces greater average weight loss.
Is Mounjaro FDA-approved for weight loss?
No. Mounjaro is FDA-approved only for type 2 diabetes. Zepbound, which contains the same tirzepatide, is the FDA-approved version for chronic weight management. Any use of Mounjaro for weight loss specifically is off-label.
Can you switch from Wegovy to Mounjaro?
Yes, and clinicians commonly do so based on insurance coverage, side effects, or inadequate weight loss response. Your prescriber typically starts the new drug at the lowest dose regardless of your final dose on the previous drug, to allow tolerance to develop to the new molecule.
Do Wegovy and Mounjaro have the same side effects?
Both share the same gastrointestinal side effect profile — nausea, vomiting, diarrhea, constipation, and abdominal pain — though tirzepatide may produce slightly more intense effects on average at maximum doses. Both carry the same boxed warning for medullary thyroid carcinoma.
Which is cheaper, Wegovy or Mounjaro?
At list prices, Mounjaro ($1,080 per month) is slightly cheaper than Wegovy ($1,349 per month). Actual out-of-pocket costs depend heavily on insurance coverage and manufacturer savings card eligibility, which favors different patients for each drug.
The Bottom Line on Wegovy vs Mounjaro
For maximum weight loss, tirzepatide-based drugs (Mounjaro for diabetes, Zepbound for weight loss) outperform semaglutide-based drugs (Ozempic for diabetes, Wegovy for weight loss) in head-to-head data. But FDA indications, insurance coverage, side effect tolerance, and individual response often matter more than a six-percentage-point difference in average weight loss. Many patients do very well on Wegovy; others respond better to tirzepatide. Work with your prescriber to match the drug to your specific situation, and don’t hesitate to switch if your first choice isn’t working. Both drugs represent major progress over anything available before 2021.