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Ozempic vs Wegovy vs Mounjaro vs Zepbound: what's the difference? What the trials found

Four brand names, but only two medicines inside them. Here is what each one is approved for in the US, the dose ranges in the official labels, and what the weight-loss trials found.

By 8 min read
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The short version
  • There are only two molecules behind the four names: semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound). In the one head-to-head trial, adults without diabetes lost 20.2% of their weight on tirzepatide and 13.7% on semaglutide over 72 weeks.4
  • The brand mostly tells you the approved use: Ozempic and Mounjaro are approved for type 2 diabetes, Wegovy and Zepbound for weight management, each with extra uses listed below.1
  • Doses differ by brand. The Ozempic label tops out at 2 mg weekly, the Wegovy label goes up to 7.2 mg, and Mounjaro and Zepbound both run from 2.5 mg to 15 mg.1

Same molecule, different brand

Semaglutide acts on one gut-hormone receptor, GLP-1. Novo Nordisk sells it as Ozempic (weekly injection), Wegovy (weekly injection or daily tablet), and Rybelsus and Ozempic tablets (daily tablets).1

Tirzepatide acts on two receptors, GIP and GLP-1. Eli Lilly sells it as Mounjaro and Zepbound, both weekly injections.1

Within each pair, the medicine is the same. What differs is the approved use, the dose range on the label, and the devices. The labels also say not to combine them: the Wegovy and Zepbound labels state that using them with other products containing the same drug, or with any other GLP-1 receptor agonist, is not recommended.1

Illustration of two pairs of matching shapes linked by lines.

Side-by-side comparison

BrandMedicine and makerFDA-approved uses (current US label)Label dose rangeForms
Ozempic injectionSemaglutide, Novo NordiskBlood sugar control in adults with type 2 diabetes; lowering risk of heart attack, stroke and CV death in adults with type 2 diabetes and heart disease; lowering risk of kidney decline, kidney failure and CV death in adults with type 2 diabetes and chronic kidney disease0.25 mg weekly to start, then 0.5, 1 or 2 mg weekly (maximum 2 mg)Multi-dose pens; single-dose prefilled syringes
Rybelsus and Ozempic tabletsSemaglutide, Novo NordiskBlood sugar control in adults with type 2 diabetes; lowering CV risk in adults with type 2 diabetes at high riskRybelsus 3 mg to start, then 7 or 14 mg daily; Ozempic tablets 1.5 mg to start, then 4 or 9 mg dailyDaily tablets
Wegovy injectionSemaglutide, Novo NordiskWeight reduction and long-term maintenance (adults, and children 12 and older with obesity); lowering CV risk in adults with heart disease and obesity or overweight; MASH with moderate to advanced liver fibrosis in adults (accelerated approval)0.25 mg weekly to start; maintenance 1.7 or 2.4 mg weekly; up to 7.2 mg for weight reduction in adultsSingle-dose pens (including a 7.2 mg pen); 4-dose FlexTouch pen; single-dose syringes
Wegovy tabletsSemaglutide, Novo NordiskWeight reduction and maintenance in adults; lowering CV risk in adults with heart disease and obesity or overweight1.5 mg daily to start; maintenance 25 mg dailyDaily tablets
MounjaroTirzepatide, Eli LillyBlood sugar control in adults and children 10 and older with type 2 diabetes; lowering CV risk in adults with type 2 diabetes at high risk2.5 mg weekly to start, rising in 2.5 mg steps; maximum 15 mg (10 mg in children)Single-dose pens and vials; multi-dose vials; 4-dose KwikPen
ZepboundTirzepatide, Eli LillyWeight reduction and long-term maintenance in adults; moderate to severe obstructive sleep apnea in adults with obesity2.5 mg weekly to start; maintenance 5, 10 or 15 mg (10 or 15 mg for sleep apnea)Single-dose pens and vials; multi-dose vials; 4-dose KwikPen
 Source: current US prescribing information on DailyMed, sections 1 (Indications and Usage), 2 (Dosage and Administration) and 3 (Dosage Forms and Strengths), checked November 2026.1 CV = cardiovascular. These are the labels' instructions, not dosing advice. Approvals differ outside the US.

A few details worth knowing. Ozempic is not approved for weight management, and Wegovy is not approved for blood sugar control, even though they contain the same drug. Zepbound's 2.5 mg dose is for starting only and is not approved as a maintenance dose. The labels also note that Rybelsus and Ozempic tablets are not interchangeable milligram for milligram.1 Oral semaglutide for weight loss has its own article: oral semaglutide (Wegovy tablet).

Which leads to more weight loss?

For years, the only way to compare was to set separate trials side by side. Those enrolled different people at different times, so the numbers below are a rough guide, not a ranking.

TrialWhoMedicine and doseAverage weight change
STEP 1, 68 weeks1,961 adults with obesity or overweight, no diabetesSemaglutide 2.4 mg weekly (Wegovy dose)−14.9% vs −2.4% placebo
SURMOUNT-1, 72 weeks2,539 adults with obesity or overweight, no diabetesTirzepatide 5 / 10 / 15 mg weekly−15.0% / −19.5% / −20.9% vs −3.1% placebo
STEP UP, 72 weeks1,407 adults with BMI 30 or more, no diabetesSemaglutide 7.2 mg vs 2.4 mg weekly−18.7% vs −15.6% (−3.9% placebo)
OASIS 4, 64 weeks307 adults with obesity or overweight, no diabetesOral semaglutide 25 mg daily−13.6% vs −2.2% placebo
 Sources: Wilding 2021, Jastreboff 2022, Wharton 2025 (STEP UP), Wharton 2025 (OASIS 4).2,3,8,9 Randomized trials; all participants also received lifestyle advice.

The head-to-head trial: SURMOUNT-5

SURMOUNT-5 randomly assigned 751 adults with obesity and without type 2 diabetes to tirzepatide (10 or 15 mg) or semaglutide (1.7 or 2.4 mg), each at the highest dose the person tolerated, for 72 weeks. It was open-label and funded by Eli Lilly.4

Tirzepatide−20.2%
Semaglutide−13.7%

Waist size fell by 18.4 cm with tirzepatide and 13.0 cm with semaglutide. The most common side effects in both groups were stomach-related and mostly mild to moderate.4 Full details: semaglutide vs tirzepatide. SURMOUNT-5 tested the 2.4 mg semaglutide dose, not the newer 7.2 mg dose.

What about people with type 2 diabetes?

People with type 2 diabetes tend to lose less weight on these medicines than people without it. Three trials help here:

  • STEP 2 (semaglutide). In 1,210 adults with type 2 diabetes and overweight or obesity, semaglutide 2.4 mg led to a 9.6% average weight loss over 68 weeks, vs 3.4% on placebo. The trial also included a 1.0 mg group, the dose used for diabetes.5
  • SURMOUNT-2 (tirzepatide). In 938 adults with type 2 diabetes and obesity or overweight, tirzepatide 10 mg and 15 mg led to 12.8% and 14.7% weight loss over 72 weeks, vs 3.2% on placebo.6
  • SURPASS-2 (head to head at diabetes doses). In 1,879 adults with type 2 diabetes, tirzepatide 5, 10 and 15 mg lowered HbA1c by 2.01, 2.24 and 2.30 percentage points over 40 weeks, vs 1.86 with semaglutide 1 mg. Weight loss was 1.9, 3.6 and 5.5 kg greater with tirzepatide.7

More on this group: GLP-1 weight loss with type 2 diabetes.

How the dosing schedules compare

All four injections are given once a week, on the same day each week, with or without food. All start at a low dose and step up in stages of at least 4 weeks, which the labels say is to reduce stomach side effects.1 The labels differ on missed doses. The Ozempic label allows a missed dose within 5 days. The Mounjaro and Zepbound labels allow 4 days. The Wegovy injection label says to take it if the next dose is more than 2 days away.1 See missed a GLP-1 dose for the full label wording.

The tablets work differently. The labels say to take them once a day on an empty stomach with up to 4 ounces of water, then wait at least 30 minutes before eating, drinking or taking other oral medicines.1

Shared warnings

All of these US labels carry the same boxed warning about thyroid C-cell tumors seen in rodents. They also list similar warnings: pancreatitis, gallbladder problems, severe stomach side effects, kidney injury from dehydration, and a risk of breathing in stomach contents during anesthesia or deep sedation.1 See GLP-1 before surgery and GLP-1 and thyroid cancer.

This article compares what the labels and trials say. It does not recommend one medicine over another. Which one fits you, and at what dose, depends on your health, your other medicines and how you respond. Those are decisions for you and your prescriber.

Common questions

What is the difference between Ozempic and Wegovy?

Ozempic and Wegovy both contain semaglutide and are both made by Novo Nordisk. In the US, Ozempic is approved for adults with type 2 diabetes at weekly doses up to 2 mg, while Wegovy is approved for weight management and heart risk reduction at a usual maintenance dose of 2.4 mg weekly, with a 7.2 mg option for weight reduction in adults.

What is the difference between Mounjaro and Zepbound?

Mounjaro and Zepbound both contain tirzepatide, made by Eli Lilly, and use the same weekly doses from 2.5 mg up to 15 mg. Mounjaro is approved for type 2 diabetes and heart risk reduction in type 2 diabetes, while Zepbound is approved for weight management and for moderate to severe obstructive sleep apnea in adults with obesity.

Which is better for weight loss, Wegovy or Zepbound?

In the SURMOUNT-5 head-to-head trial of 751 adults with obesity and without diabetes, average weight loss over 72 weeks was 20.2% with tirzepatide (Zepbound) and 13.7% with semaglutide (Wegovy). Which medicine suits a person depends on their health, side effects and coverage, and is a decision for them and their prescriber.

Are the doses of Ozempic and Wegovy the same?

No. Both start at 0.25 mg weekly, but the Ozempic label's maximum is 2 mg weekly, while the Wegovy label's maintenance dose for weight reduction in adults is 1.7 mg or 2.4 mg weekly, with an option to go up to 7.2 mg.

Do Ozempic and Mounjaro cause weight loss in people with diabetes?

Yes, though usually less than in people without diabetes. In the SURPASS-2 trial of 1,879 adults with type 2 diabetes, tirzepatide (Mounjaro) at 5, 10 and 15 mg led to 1.9 to 5.5 kg more weight loss than semaglutide 1 mg (the Ozempic dose) over 40 weeks.

Sources

  1. US prescribing information on DailyMed: WEGOVY injection and tablets, OZEMPIC injection, RYBELSUS and OZEMPIC tablets, ZEPBOUND, MOUNJARO (2026 versions, checked November 2026).
  2. 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 · PubMed
  3. 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 · PubMed
  4. Aronne LJ, Horn DB, le Roux CW, et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity. N Engl J Med. 2025;393(1):26-36. doi:10.1056/NEJMoa2416394 · PubMed
  5. Davies M, Færch L, Jeppesen OK, et al. Semaglutide 2·4 mg once a week in adults with overweight or obesity, and type 2 diabetes (STEP 2): a randomised, double-blind, double-dummy, placebo-controlled, phase 3 trial. Lancet. 2021;397(10278):971-984. doi:10.1016/S0140-6736(21)00213-0 · PubMed
  6. Garvey WT, Frias JP, Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2): a double-blind, randomised, multicentre, placebo-controlled, phase 3 trial. Lancet. 2023;402(10402):613-626. doi:10.1016/S0140-6736(23)01200-X · PubMed
  7. Frías JP, Davies MJ, Rosenstock J, et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes. N Engl J Med. 2021;385(6):503-515. doi:10.1056/NEJMoa2107519 · PubMed
  8. Wharton S, Freitas P, Hjelmesæth J, et al. Once-weekly semaglutide 7·2 mg in adults with obesity (STEP UP): a randomised, controlled, phase 3b trial. Lancet Diabetes Endocrinol. 2025;13(11):949-963. doi:10.1016/S2213-8587(25)00226-8 · PubMed
  9. Wharton S, Lingvay I, Bogdanski P, et al. Oral Semaglutide at a Dose of 25 mg in Adults with Overweight or Obesity. N Engl J Med. 2025;393(11):1077-1087. doi:10.1056/NEJMoa2500969 · PubMed
This article summarises published research for general information. It is not medical advice and does not replace advice from your own care team. Never change a medication or dose without talking to your prescriber.

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