Wegovy vs Mounjaro: Key Differences Explained

Wegovy and Mounjaro are prescription medicines used in metabolic disease and weight-management care, but they are not the same medicine.

Wegovy contains semaglutide, a GLP-1 receptor agonist, while Mounjaro contains tirzepatide, which activates both GIP and GLP-1 receptors. Their approved indications, available formulations and regulatory status also differ between countries.

Understanding these differences is important because the brand name alone does not always indicate the same approved use in every market.

Wegovy vs Mounjaro at a Glance

Both medicines affect pathways involved in appetite, food intake and metabolic regulation, but tirzepatide acts on two incretin receptors rather than one.

What Is Wegovy?

Wegovy is a prescription medicine containing semaglutide, a GLP-1 receptor agonist.

GLP-1, or glucagon-like peptide-1, is a naturally occurring hormone involved in appetite regulation, insulin secretion and glucose metabolism.

Semaglutide activates GLP-1 receptors and can influence areas of the brain involved in appetite and food intake. It also slows gastric emptying and affects glucose-dependent insulin and glucagon responses.

Wegovy was originally introduced as a once-weekly subcutaneous injection. However, formulation should now be specified when discussing the product.

In the United States, the FDA has also approved once-daily oral Wegovy tablets containing semaglutide for certain adult indications. The current U.S. label therefore includes both injectable and oral Wegovy formulations.

Availability of oral Wegovy outside the United States may differ.

What Is Mounjaro?

Mounjaro is a prescription medicine containing tirzepatide, a dual GIP and GLP-1 receptor agonist.

Tirzepatide activates two incretin hormone receptors:

• GIP: glucose-dependent insulinotropic polypeptide receptor
• GLP-1: glucagon-like peptide-1 receptor

Through these pathways, tirzepatide influences glucose-dependent insulin secretion, glucagon regulation, appetite and food intake.

Mounjaro is administered by subcutaneous injection once weekly.

The important regulatory point is that the approved indication attached to the Mounjaro brand differs by country.

GLP-1 vs GIP + GLP-1: How Do Their Mechanisms Differ?

The main pharmacologic difference is that semaglutide targets GLP-1 receptors, while tirzepatide targets both GIP and GLP-1 receptors.

Semaglutide

Semaglutide mimics the activity of GLP-1.

GLP-1 receptor activation can:

• increase glucose-dependent insulin secretion
• reduce inappropriate glucagon secretion
• influence appetite-regulating pathways
• reduce food intake
• delay gastric emptying

Tirzepatide

Tirzepatide activates both GIP and GLP-1 receptors.

The combination influences glucose regulation and energy intake through two incretin pathways rather than one.

This pharmacologic difference does not by itself determine which treatment is appropriate for an individual. Treatment choice also depends on approved indications, medical history, tolerability, concomitant medications and clinical goals.

Wegovy vs Mounjaro: What Does the Clinical Evidence Show?

A direct clinical trial has compared tirzepatide with semaglutide in adults with obesity without type 2 diabetes.

The phase 3b SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, randomly assigned 751 adults with obesity without diabetes to maximum tolerated doses of:

• tirzepatide 10 mg or 15 mg once weekly, or
• semaglutide 1.7 mg or 2.4 mg once weekly.

After 72 weeks, the mean percentage change in body weight was:

Waist circumference decreased by an average of 18.4 cm with tirzepatide and 13.0 cm with semaglutide.

The most commonly reported adverse events in both groups were gastrointestinal and were generally mild to moderate, particularly during dose escalation.

These findings need to be interpreted within the specific trial population and dosing protocol.

Importantly, SURMOUNT-5 compared the active medicines tirzepatide and semaglutide for obesity treatment. It does not mean that the Mounjaro brand has an obesity indication in every country.

The study was also funded by Eli Lilly, the manufacturer of tirzepatide, which should be considered when interpreting the evidence alongside other independent and regulatory sources.

Approved Uses Differ by Country

Wegovy and Mounjaro should not be assumed to have identical indications internationally.

United States

In the United States, Mounjaro is FDA-approved as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes.

For tirzepatide used specifically for chronic weight management in the United States, the relevant brand is Zepbound, not Mounjaro.

Wegovy has FDA-approved indications that include long-term weight reduction in eligible patients. The injectable formulation also has additional approved indications, including cardiovascular risk reduction in certain adults and treatment of noncirrhotic MASH with F2–F3 fibrosis under accelerated approval.

FDA-approved Wegovy tablets are also available for weight reduction and cardiovascular risk reduction in eligible adults.

European Union

In the EU, Wegovy is authorized for weight management in eligible adults and certain adolescents.

Mounjaro has both type 2 diabetes and adult weight-management indications in the EU.

South Korea

In South Korea, Wegovy is approved for weight management, including use in eligible adults and adolescents according to the Korean product information.

Mounjaro has Korean MFDS-approved indications including adult type 2 diabetes, chronic weight management in eligible adults, and treatment of moderate-to-severe obstructive sleep apnea in adults with obesity under the conditions specified in the local label.

Because indications can change over time, the current local regulatory label should always be checked before discussing an approved use.

How Are Wegovy and Mounjaro Administered?

Both medicines are available as injectable therapies, but Wegovy now also has an oral formulation in some markets.

Injectable Wegovy is generally administered subcutaneously once weekly using a gradual dose-escalation schedule.

Mounjaro is also administered subcutaneously once weekly, beginning at a lower dose and increasing gradually according to the approved label and individual tolerability.

In the United States, Wegovy tablets are taken once daily. The FDA label specifies administration on an empty stomach in the morning with water, followed by a waiting period of at least 30 minutes before food, beverages or other oral medicines.

Therefore, statements such as “Wegovy is always a weekly injection” are no longer accurate globally.

What About Side Effects?

Both semaglutide and tirzepatide commonly cause gastrointestinal adverse effects, particularly during dose escalation.

Reported effects can include:

• nausea
• diarrhea
• vomiting
• constipation
• abdominal discomfort or pain
• dyspepsia
• reduced appetite

Both medicines also carry warnings or precautions related to potentially serious conditions such as pancreatitis, gallbladder disease, severe gastrointestinal reactions and kidney injury associated with volume depletion.

U.S. prescribing information for both Wegovy and Mounjaro includes a boxed warning concerning thyroid C-cell tumors observed in rodents. It is unknown whether these medicines cause medullary thyroid carcinoma in humans. Both are contraindicated in patients with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2 under the U.S. labels.

Individual risks can differ according to medical history, other medications and the specific indication being treated.

Wegovy vs Mounjaro: The Key Difference

Wegovy and Mounjaro belong to the same broader incretin-treatment conversation, but they are pharmacologically and regulatorily different medicines.

Wegovy contains semaglutide and primarily targets GLP-1 receptors.

Mounjaro contains tirzepatide and activates both GIP and GLP-1 receptors.

Clinical trials have reported substantial weight reduction with both molecules, and the SURMOUNT-5 head-to-head trial reported a larger average weight reduction with tirzepatide than semaglutide under its specific 72-week study conditions.

However, treatment decisions should not be based on a single efficacy number.

Approved indication, cardiovascular or metabolic disease, diabetes status, adverse-effect profile, concomitant medications, formulation preferences and local regulatory approval all need to be considered by a qualified healthcare professional.

Frequently Asked Questions

Is Wegovy the same as Mounjaro?

No. Wegovy contains semaglutide, while Mounjaro contains tirzepatide. Semaglutide is a GLP-1 receptor agonist, whereas tirzepatide activates both GIP and GLP-1 receptors.

Which resulted in more weight loss in clinical trials?

In the 72-week SURMOUNT-5 head-to-head trial involving adults with obesity without type 2 diabetes, tirzepatide was associated with a mean body-weight reduction of 20.2%, compared with 13.7% with semaglutide. These results apply to the specific trial population, doses and study design and should not be interpreted as a guaranteed individual outcome.

Are Wegovy and Mounjaro both GLP-1 drugs?

They both involve GLP-1 signaling, but their mechanisms are not identical. Semaglutide acts as a GLP-1 receptor agonist, while tirzepatide acts as a dual GIP and GLP-1 receptor agonist.

Are both medicines once-weekly injections?

Injectable Wegovy and Mounjaro are administered once weekly. However, Wegovy is no longer exclusively injectable: once-daily Wegovy tablets are FDA-approved in the United States, and formulation availability varies between countries.

Is Mounjaro approved for weight loss everywhere?

No. Approved indications vary by jurisdiction. For example, Mounjaro is approved for adult weight management in the EU and South Korea, whereas in the United States the Mounjaro brand is approved for type 2 diabetes and the tirzepatide brand used for chronic weight management is Zepbound.

Do Wegovy and Mounjaro have similar side effects?

There is considerable overlap, particularly gastrointestinal effects such as nausea, diarrhea, vomiting and constipation. The exact safety profile, contraindications and warnings should be reviewed in the current prescribing information for the relevant country.

How should someone choose between Wegovy and Mounjaro?

The choice cannot be determined from weight-loss percentages alone. A licensed healthcare professional should consider the approved indication, medical history, diabetes status, other medications, contraindications, potential adverse effects and available formulations before prescribing either medicine.

References

1. Aronne LJ, et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity. New England Journal of Medicine. 2025;393:26–36. SURMOUNT-5.
2. U.S. Food and Drug Administration. Wegovy (semaglutide) Prescribing Information. Current 2026 labeling.
3. U.S. Food and Drug Administration. Mounjaro (tirzepatide) Prescribing Information.
4. European Medicines Agency. Wegovy EPAR.
5. European Medicines Agency. Mounjaro EPAR.
6. Korea regulatory/product information for Wegovy and Mounjaro. Current product information should be checked through MFDS and the relevant authorized manufacturer information.

Disclaimer

This content is for general educational purposes only and is not medical advice. Wegovy and Mounjaro are prescription-only medicines and must be prescribed by a licensed healthcare professional. Approval status, formulations and availability vary by country. Always consult local regulatory guidance and a qualified physician before making treatment decisions.

Regulatory status reflects information available at publication and may change; verify with the relevant authority, including the FDA, EMA, MHRA or MFDS.