GLP-1 Weight Loss Comparison: Ozempic vs Mounjaro vs Wegovy vs Zepbound

A data-driven, side-by-side comparison of the four leading GLP-1 weight loss medications based on clinical trial evidence, cost, dosing, and side effect profiles.

GLP-1 receptor agonists have transformed the weight loss landscape, but choosing between Ozempic, Mounjaro, Wegovy, and Zepbound requires understanding how they differ in efficacy, dosing, and cost. This guide compiles data from the largest randomized controlled trials to help you make an informed comparison.

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Table of Contents

How GLP-1 Medications Compare

All four medications are injectable GLP-1 receptor agonists given once weekly by subcutaneous injection. Ozempic and Wegovy both contain semaglutide (made by Novo Nordisk), while Mounjaro and Zepbound both contain tirzepatide (made by Eli Lilly). The key difference: tirzepatide is a dual GIP/GLP-1 agonist, which clinical trials show produces roughly 50% more weight loss than semaglutide alone.[1][2]

The table below summarizes the fundamental differences between these four medications. While Ozempic and Wegovy share the same active ingredient, they differ in approved indication and maximum dose. The same relationship applies to Mounjaro and Zepbound.[3]

Feature Ozempic Wegovy Mounjaro Zepbound
Generic Name Semaglutide Semaglutide Tirzepatide Tirzepatide
Manufacturer Novo Nordisk Novo Nordisk Eli Lilly Eli Lilly
FDA Approval Year 2017 2021 2022 2023
FDA-Approved For Type 2 Diabetes Chronic Weight Management Type 2 Diabetes Chronic Weight Management
Mechanism GLP-1 agonist GLP-1 agonist Dual GIP/GLP-1 agonist Dual GIP/GLP-1 agonist
Administration Weekly injection Weekly injection Weekly injection Weekly injection
Max Dose 2.0 mg 2.4 mg 15 mg 15 mg

Important Distinction

Ozempic and Mounjaro are FDA-approved for type 2 diabetes, not weight loss. When prescribed for weight loss, this is considered "off-label" use. Wegovy and Zepbound are the versions specifically approved for chronic weight management in adults with obesity (BMI 30+) or overweight (BMI 27+) with at least one weight-related comorbidity.[4]

Weight Loss Results by Medication

Tirzepatide (Mounjaro/Zepbound) at the highest dose produces approximately 22.5% body weight loss at 72 weeks, while semaglutide (Ozempic/Wegovy) produces approximately 14.9% at 68 weeks. For a person starting at 220 lbs, that translates to roughly 50 lbs lost on tirzepatide versus 33 lbs on semaglutide.[1][2]

The data below comes from the two landmark clinical trial programs: STEP (semaglutide) and SURMOUNT (tirzepatide). These are the largest randomized, double-blind, placebo-controlled trials conducted for each medication.

Medication Trial Duration Dose Participants (n) Avg % Body Weight Loss Avg lbs Lost (220 lb person)
Wegovy (semaglutide) STEP 1 68 weeks 2.4 mg 1,961 14.9% ~33 lbs
Ozempic (semaglutide) STEP 1* 68 weeks 2.4 mg* 1,961 14.9%* ~33 lbs
Zepbound (tirzepatide) SURMOUNT-1 72 weeks 15 mg 2,539 22.5% ~50 lbs
Mounjaro (tirzepatide) SURMOUNT-1* 72 weeks 15 mg* 2,539 22.5%* ~50 lbs
Mounjaro (tirzepatide) SURMOUNT-1 72 weeks 10 mg 2,539 21.4% ~47 lbs
Mounjaro (tirzepatide) SURMOUNT-1 72 weeks 5 mg 2,539 15.0% ~33 lbs
Placebo STEP 1 68 weeks N/A 655 2.4% ~5 lbs
Placebo SURMOUNT-1 72 weeks N/A 643 3.1% ~7 lbs

*Ozempic and Mounjaro were studied under their weight-loss branded counterparts (Wegovy and Zepbound respectively) in these obesity trials. The active ingredient is identical. Ozempic's FDA-approved max dose for diabetes is 2.0 mg, while the STEP 1 trial used 2.4 mg (the Wegovy dose).[1][2]

What These Numbers Mean in Practice

The difference between 14.9% and 22.5% body weight loss is clinically significant. For a 220 lb person, tirzepatide at the highest dose produces roughly 17 additional pounds of weight loss compared to semaglutide. However, even the lowest tirzepatide dose (5 mg) produces weight loss comparable to the highest semaglutide dose (2.4 mg).[2]

Individual results vary substantially. In the SURMOUNT-1 trial, approximately 36% of participants on tirzepatide 15 mg lost 25% or more of their body weight, while some participants experienced minimal weight loss.[2]

Want to estimate your personal weight loss trajectory? Use our medication-specific calculators: Ozempic Weight Loss Calculator, Mounjaro Weight Loss Calculator, or Wegovy Weight Loss Calculator.

Dosage Schedules Compared

All four medications follow a gradual dose-escalation schedule to minimize gastrointestinal side effects. Semaglutide (Ozempic/Wegovy) takes approximately 16-20 weeks to reach the maintenance dose, while tirzepatide (Mounjaro/Zepbound) takes approximately 20-32 weeks depending on tolerability.[5][6]
Phase Ozempic Wegovy Mounjaro Zepbound
Starting Dose 0.25 mg/week 0.25 mg/week 2.5 mg/week 2.5 mg/week
Titration Step 2 0.5 mg (wk 5) 0.5 mg (wk 5) 5 mg (wk 5) 5 mg (wk 5)
Titration Step 3 1.0 mg (wk 9) 1.0 mg (wk 9) 7.5 mg (wk 9) 7.5 mg (wk 9)
Titration Step 4 -- 1.7 mg (wk 13) 10 mg (wk 13) 10 mg (wk 13)
Maintenance Dose 1.0-2.0 mg (wk 9+) 2.4 mg (wk 17+) 5-15 mg (wk 17+) 5-15 mg (wk 17+)
Time to Full Dose 8-16 weeks 16-20 weeks 16-32 weeks 16-32 weeks
Titration Flexibility Moderate Fixed schedule High (3 maintenance doses) High (3 maintenance doses)

Tirzepatide offers more dosing flexibility because it has three effective maintenance doses (5 mg, 10 mg, and 15 mg), allowing prescribers to balance efficacy against tolerability. Some patients achieve satisfactory weight loss at 5 mg or 10 mg without needing the highest dose.[6] For detailed dosing guidance, see our Ozempic Dosage Calculator.

Side Effects Comparison

All GLP-1 medications share a similar gastrointestinal side effect profile. Nausea is the most common side effect, affecting 40-44% of patients across all four drugs. Side effects are generally most severe during dose escalation and improve as the body adjusts. Tirzepatide and semaglutide have comparable side effect rates at their respective therapeutic doses.[7][8]
Side Effect Ozempic/Wegovy (Semaglutide) Mounjaro/Zepbound (Tirzepatide) Placebo
Nausea 44% 40% 16%
Diarrhea 30% 31% 12%
Vomiting 24% 22% 6%
Constipation 23% 23% 5%
Abdominal Pain 20% 14% 8%
Headache 14% 12% 10%
Fatigue 11% 9% 5%
Injection Site Reaction 3-5% 3-7% 1%
Discontinuation Due to Side Effects 7% 6% 3%

Side effect rates compiled from STEP 1 and SURMOUNT-1 trial safety data.[7][8]

Serious but Rare Side Effects

Both drug classes carry warnings for pancreatitis, gallbladder disease, and potential thyroid C-cell tumors (observed in rodent studies). Tirzepatide and semaglutide both carry a boxed warning regarding thyroid C-cell tumors and are contraindicated in patients with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2.[9]

These medications should only be used under medical supervision. Report any persistent severe abdominal pain, signs of pancreatitis, or thyroid lumps to your healthcare provider immediately.

Cost Comparison

Without insurance, all four GLP-1 medications cost between $900 and $1,350 per month. Wegovy is the most expensive at list price. With commercial insurance that covers these medications, out-of-pocket costs typically range from $25 to $150 per month, though coverage varies significantly by plan.[10]
Cost Factor Ozempic Wegovy Mounjaro Zepbound
Monthly Cost (Without Insurance) $900 - $1,000 $1,300 - $1,350 $1,000 - $1,100 $1,000 - $1,100
Monthly Cost (With Insurance) $25 - $150 $25 - $150 $25 - $150 $25 - $150
Manufacturer Savings Program Yes (for eligible patients) Yes (for eligible patients) Yes (for eligible patients) Yes (for eligible patients)
Medicare Coverage Yes (for diabetes) Limited (varies by plan) Yes (for diabetes) Limited (varies by plan)
Annual Cost (Without Insurance) $10,800 - $12,000 $15,600 - $16,200 $12,000 - $13,200 $12,000 - $13,200

Prices reflect approximate U.S. retail pricing as of early 2026 and may vary by pharmacy and location. Actual out-of-pocket costs depend on individual insurance plans.[10]

Insurance Coverage Tips

  • Diabetes indication helps: Ozempic and Mounjaro are more likely to be covered because they have FDA approval for type 2 diabetes, which insurers are required to cover under many plans.
  • Prior authorization: Most insurers require prior authorization for GLP-1 medications, often requiring documented failed attempts at diet and exercise.
  • Step therapy: Some plans require trying cheaper medications first (such as metformin or phentermine) before approving a GLP-1.
  • Savings cards: Both Novo Nordisk and Eli Lilly offer manufacturer savings programs that can reduce copays to as low as $25/month for commercially insured patients.[11]

Which GLP-1 Is Right for You?

The best GLP-1 medication depends on your primary goal (diabetes management vs. weight loss), insurance coverage, and how your body responds to the medication. Tirzepatide generally produces more weight loss, but semaglutide has a longer track record and more cardiovascular outcome data.[12]

Choose Semaglutide (Ozempic/Wegovy) If:

  • You have type 2 diabetes AND want weight loss (Ozempic covers both)
  • Cardiovascular risk reduction is a priority -- semaglutide has proven CV outcomes data from the SELECT trial[12]
  • Your insurance covers semaglutide but not tirzepatide
  • You prefer a medication with a longer real-world track record (available since 2017)
  • You want the FDA-approved weight loss version specifically (Wegovy)

Choose Tirzepatide (Mounjaro/Zepbound) If:

  • Maximum weight loss is your primary goal (22.5% vs. 14.9%)
  • You tried semaglutide and plateaued or had insufficient response
  • You want more dosing flexibility (3 maintenance dose options)
  • Blood sugar control is also a concern -- tirzepatide shows strong A1C reduction[2]
  • Your insurance covers tirzepatide or cost is not a barrier

A Note on Off-Label Use

Many patients use Ozempic or Mounjaro off-label for weight loss because their insurance covers the diabetes indication but not the weight-loss branded versions (Wegovy/Zepbound). While the active ingredients are identical, the approved doses differ. Discuss this with your prescriber to understand the implications for your specific situation.

Timeline: When to Expect Results

Most patients notice meaningful weight loss starting around weeks 8-12, after the initial dose titration period. The bulk of weight loss occurs in the first 40-52 weeks, with results plateauing around 60-72 weeks. Tirzepatide users typically see faster and greater weight loss at each time point compared to semaglutide users.[1][2]
Wk 4

Month 1: Titration Begins

Semaglutide: 1-2% body weight loss (~2-4 lbs at 220 lbs). Appetite suppression noticeable but dose is still low (0.25 mg). Tirzepatide: 1-3% body weight loss (~2-7 lbs). Starting dose is 2.5 mg.

Wk 12

Month 3: Weight Loss Accelerates

Semaglutide: 5-8% body weight loss (~11-18 lbs). Dose has increased to 1.0-1.7 mg. Tirzepatide: 7-10% body weight loss (~15-22 lbs). Dose is typically 7.5-10 mg. Gastrointestinal side effects typically peak and begin to subside.

Wk 24

Month 6: Significant Results

Semaglutide: 10-12% body weight loss (~22-26 lbs). At full maintenance dose of 2.4 mg. Tirzepatide: 15-18% body weight loss (~33-40 lbs). Most patients at 10-15 mg by this point.

Wk 40

Month 10: Approaching Plateau

Semaglutide: 13-14% body weight loss (~29-31 lbs). Rate of loss slowing. Tirzepatide: 20-22% body weight loss (~44-48 lbs). Most significant weight loss window is closing.

Wk 68-72

Months 16-18: Maximum Results

Semaglutide: 14.9% body weight loss (~33 lbs) as observed in STEP 1 at 68 weeks.[1] Tirzepatide: 22.5% body weight loss (~50 lbs) as observed in SURMOUNT-1 at 72 weeks.[2] Weight loss has largely plateaued for most patients.

These timelines reflect averages from clinical trials. Individual results vary based on adherence, diet, exercise, starting weight, and metabolic factors. For a personalized projection, try our Ozempic Weight Loss Calculator or Mounjaro Weight Loss Calculator.

Frequently Asked Questions

Which GLP-1 medication causes the most weight loss?

Tirzepatide (Mounjaro/Zepbound) produces the most weight loss in clinical trials. At the 15 mg dose, participants lost an average of 22.5% of body weight over 72 weeks in the SURMOUNT-1 trial (n=2,539), compared to 14.9% with semaglutide 2.4 mg (Wegovy) over 68 weeks in the STEP 1 trial (n=1,961).[1][2]

How much weight can you lose on Ozempic in 3 months?

Most patients lose 5-8% of their body weight in the first 3 months on Ozempic, which translates to roughly 11-18 pounds for someone starting at 220 lbs. Weight loss accelerates after the initial titration period as the dose increases from 0.25 mg to the therapeutic range.

Is Mounjaro better than Ozempic for weight loss?

Clinical trial data suggests tirzepatide (Mounjaro) produces greater weight loss than semaglutide (Ozempic). SURMOUNT-1 showed 22.5% body weight loss with tirzepatide 15 mg at 72 weeks, while STEP 1 showed 14.9% with semaglutide 2.4 mg at 68 weeks. However, these were separate trials with different patient populations, so direct comparison has limitations. Individual responses vary, and some patients respond better to semaglutide.[1][2]

What is the difference between Ozempic and Wegovy?

Ozempic and Wegovy both contain semaglutide and are made by Novo Nordisk. Ozempic is FDA-approved for type 2 diabetes (maximum dose 2.0 mg), while Wegovy is approved specifically for chronic weight management at a higher maximum dose (2.4 mg). The active ingredient is identical; the differences are the approved indication, maximum dose, and the available pen concentrations.[3]

How much do GLP-1 medications cost per month?

Without insurance, GLP-1 medications cost approximately $900-$1,350 per month. Ozempic runs about $900-$1,000/month, Wegovy about $1,300-$1,350/month, Mounjaro about $1,000-$1,100/month, and Zepbound about $1,000-$1,100/month. With commercial insurance coverage, copays typically range from $25-$150/month depending on the plan.[10]

What are the most common side effects of GLP-1 medications?

The most common side effects across all GLP-1 medications are gastrointestinal: nausea (40-44% of patients), diarrhea (30%), vomiting (24%), and constipation (23%). These side effects are typically most pronounced during dose titration and tend to improve over time. Serious but rare side effects include pancreatitis, gallbladder problems, and changes in vision for diabetic patients.[7][8]

Do you regain weight after stopping GLP-1 medications?

Research indicates that most patients regain approximately two-thirds of lost weight within one year of stopping GLP-1 medications. The STEP 1 extension trial showed participants regained about 11.6 percentage points of the 17.3% body weight they had lost after discontinuing semaglutide for one year. This suggests these medications may require long-term use for sustained results.[13]

Can you take Ozempic and Mounjaro together?

No, Ozempic and Mounjaro should not be taken together. Both are GLP-1 receptor agonists, and combining them would increase the risk of severe gastrointestinal side effects and potentially dangerous drops in blood sugar. Patients should use one GLP-1 medication at a time under medical supervision. Switching between medications is possible but should be done under a prescriber's guidance.

Estimate your GLP-1 weight loss

Use our medication-specific calculators for personalized weight loss projections based on clinical trial data.

Ozempic Calculator Mounjaro Calculator

References

  1. Wilding JPH, Batterham RL, Calanna S, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2021;384(11):989-1002. doi:10.1056/NEJMoa2032183 (STEP 1 trial)
  2. Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022;387(3):205-216. doi:10.1056/NEJMoa2206038 (SURMOUNT-1 trial)
  3. U.S. Food and Drug Administration. FDA Approves New Drug Treatment for Chronic Weight Management. FDA News Release. June 2021.
  4. U.S. Food and Drug Administration. FDA Approves Novel, Dual-Targeted Treatment for Type 2 Diabetes (Mounjaro). FDA News Release. May 2022.
  5. Novo Nordisk. Ozempic (semaglutide) Prescribing Information. Revised 2024.
  6. Eli Lilly and Company. Mounjaro (tirzepatide) Prescribing Information. Revised 2024.
  7. Wilding JPH, Batterham RL, Calanna S, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity -- Supplementary Appendix. N Engl J Med. 2021. (STEP 1 safety data)
  8. Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity -- Supplementary Appendix. N Engl J Med. 2022. (SURMOUNT-1 safety data)
  9. U.S. Food and Drug Administration. Highlights of Prescribing Information: Boxed Warning for Semaglutide and Tirzepatide Products. FDA.gov.
  10. GoodRx. GLP-1 Medication Price Comparison. GoodRx.com. Accessed March 2026.
  11. Novo Nordisk. Wegovy Savings Offer. NovoCare.com; Eli Lilly. Zepbound Savings Card. LillyDirect.com. Accessed March 2026.
  12. Lincoff AM, Brown-Frandsen K, Colhoun HM, et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. N Engl J Med. 2023;389(24):2221-2232. doi:10.1056/NEJMoa2307563 (SELECT trial)
  13. Wilding JPH, Batterham RL, Davies M, et al. Weight Regain and Cardiometabolic Effects After Withdrawal of Semaglutide. Diabetes Obes Metab. 2022;24(8):1553-1564. doi:10.1111/dom.14725