Mounjaro vs Zepbound: Same Drug, Different Approved Uses

Mounjaro and Zepbound are the same active medicine — tirzepatide injection for subcutaneous use, made by Eli Lilly and Company — sold under two different brand names with two different FDA approvals ^{[1] [2] [3] [4]}. Both are dual agonists, meaning one molecule activates both the GIP receptor and the GLP-1 receptor, and both labels state “Initial U.S. Approval: 2022” ^{[1] [2] [6]}. What actually differs is what the FDA has approved each brand to treat, plus the paperwork behind them: Mounjaro was approved under NDA 215866 on May 13, 2022, and Zepbound under a separate application, NDA 217806, on November 8, 2023 ^{[3] [4]}.

In practice, the brand follows the condition being treated. Mounjaro’s label covers type 2 diabetes and, as of August 27, 2026, reducing cardiovascular risk in adults with type 2 diabetes ^{[2] [3]}. Zepbound’s label covers long-term weight management and, since December 20, 2024, moderate to severe obstructive sleep apnea in adults with obesity ^{[1] [4] [7]}. What differs between them is the approved uses, the maintenance-dosing rules and the lists of common side effects ^{[1] [2]}.

Is Mounjaro the same as Zepbound?

As medicines, yes. Both brands contain tirzepatide injection, solution, for subcutaneous use, packaged by Eli Lilly and Company ^{[1] [2]}. Both work the same way in the body — each label describes the drug as a glucose-dependent insulinotropic polypeptide (GIP) receptor and glucagon-like peptide-1 (GLP-1) receptor agonist ^{[1] [2] [6]}.

As products, they are separate. Mounjaro is approved under NDA 215866 and Zepbound under NDA 217806 — two distinct new drug applications filed by the same company ^{[3] [4]}. Each brand carries its own set of NDC codes ^{[1] [2]}. Lilly describes Mounjaro as the #1 prescribed branded type 2 diabetes medicine for adults in the U.S. ^[6].

The Zepbound label carries a limitation of use: coadministration with other tirzepatide-containing products or with any GLP-1 receptor agonist is not recommended ^{[1] [7]}.

What is the difference between Mounjaro and Zepbound?

The approved uses. The two labels share the same dose strengths, the same pen and vial presentations, the same boxed warning and the same contraindications ^{[1] [2]}. The indications do not overlap at all, and the maintenance-dosing rules and common side-effect lists differ as well ^{[1] [2]}.

	Mounjaro	Zepbound
Active ingredient	Tirzepatide [2]	Tirzepatide [1]
FDA application	NDA 215866 [3]	NDA 217806 [4]
Original approval	May 13, 2022 [3]	November 8, 2023 [4]
Approved use 1	Improve glycemic control, with diet and exercise, in adults and pediatric patients 10 years and older with type 2 diabetes [2] [6]	Reduce excess body weight and maintain weight reduction long term, with a reduced-calorie diet and increased activity, in adults with obesity, or overweight plus at least one weight-related comorbid condition [1] [7]
Approved use 2	Reduce risk of major adverse cardiovascular events (CV death, non-fatal heart attack, non-fatal stroke) in adults with type 2 diabetes at high risk [2] [6]	Treat moderate to severe obstructive sleep apnea in adults with obesity [1] [7]
Weight-loss indication?	No — the U.S. label carries none [2]	Yes [1]
Approved in children?	Yes, ages 10 and older for type 2 diabetes; not known to be safe and effective under 10 [2] [6]	Not known to be safe and effective in children [7]

Mounjaro’s label contains no weight-management indication in the United States ^[2]. Zepbound’s label contains no glycemic-control indication ^[1].

Why does one drug have two brand names?

Because the FDA approved it twice, for different populations. Tirzepatide first reached the market as Mounjaro, approved on May 13, 2022, as a Type 1 New Molecular Entity under priority review ^[3]. Lilly then won a separate approval for the same molecule as Zepbound on November 8, 2023, also under priority review, this time for weight management ^[4].

Each brand has since picked up its own additions:

• Zepbound gained the obstructive sleep apnea indication on December 20, 2024, through supplement SUPPL-13, classified by FDA as Efficacy-New Indication ^{[4] [7]}.
• Mounjaro gained pediatric patients 10 years and older on December 19, 2025, through SUPPL-39 ^[3]. That approval fulfilled a postmarketing requirement (PMR 4271-1) from the original May 13, 2022 approval letter, which called for a 30-week randomized, placebo-controlled study in ages 10 to 17 followed by a 22-week open-label extension — trial I8F-MC-GPGV ^[5].
• Mounjaro gained the cardiovascular indication on August 27, 2026, through two supplements acted on the same day: SUPPL-44 (Efficacy-New Indication) and SUPPL-45 (Efficacy-New Dosing Regimen) ^[3]. Lilly announced the approval on August 28, 2026 ^[6].

How do the dosages compare?

The strength lineup is identical. Both brands come in single-dose pens or vials at 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg per 0.5 mL ^{[1] [2]}. Both labels set the recommended starting dosage at 2.5 mg injected subcutaneously once weekly ^{[1] [2]}.

From there, the escalation language differs. The Mounjaro label states that if additional glycemic control is needed, the dosage is increased in 2.5 mg increments after at least 4 weeks on the current dose ^[2]. The Zepbound label specifies 2.5 mg once weekly for 4 weeks, then an increase in 2.5 mg increments after at least 4 weeks until the recommended maintenance dosage is achieved ^[1].

Dosing item	Mounjaro	Zepbound
Starting dose	2.5 mg once weekly [2]	2.5 mg once weekly for 4 weeks [1]
Titration	2.5 mg increments after at least 4 weeks, if additional glycemic control is needed [2]	2.5 mg increments after at least 4 weeks until maintenance dosage is reached [1]
Maintenance — diabetes	The label highlights specify no maintenance-dose range; increases follow the glycemic-control rule above [2]	Not applicable
Maintenance — weight	Not applicable	5 mg, 10 mg, or 15 mg once weekly [1]
Maintenance — OSA	Not applicable	10 mg or 15 mg once weekly [1]
Maximum — adults	15 mg once weekly [2]	15 mg once weekly [1]
Maximum — pediatric 10 years and older	10 mg once weekly [2]	Not applicable

The Zepbound label directs prescribers to consider treatment response and tolerability when selecting the maintenance dosage ^[1]. The Mounjaro label flags its Recommended Dosage section (2.1) as a recent major change dated 08/2026 ^[2]. Separately, FDA approved Mounjaro supplement SUPPL-45, categorized as Efficacy-New Dosing Regimen, with an action date of August 27, 2026 ^[3].

Administration instructions on the Mounjaro label call for once-weekly dosing at any time of day, with or without meals, injected into the abdomen or thigh — or the back of the upper arm by another person — with rotation of injection sites ^[2].

What pens and vials does each brand come in?

The same presentations, under each brand’s name. Both offer a single-dose pen or single-dose vial at 2.5, 5, 7.5, 10, 12.5, or 15 mg per 0.5 mL, and both offer a multi-dose vial or a single-patient-use KwikPen that delivers four doses: 10 mg/2.4 mL (four 2.5 mg doses), 20 mg/2.4 mL (four 5 mg doses), 30 mg/2.4 mL (four 7.5 mg doses), 40 mg/2.4 mL (four 10 mg doses), 50 mg/2.4 mL (four 12.5 mg doses), or 60 mg/2.4 mL (four 15 mg doses) ^{[1] [2]}.

FDA’s drug database lists MOUNJARO, MOUNJARO (AUTOINJECTOR), and MOUNJARO KWIKPEN products under NDA 215866, and ZEPBOUND, ZEPBOUND (AUTOINJECTOR), and ZEPBOUND KWIKPEN under NDA 217806 ^{[3] [4]}. The KwikPen labeling supplements for both brands were approved the same day, January 20, 2026 — Mounjaro SUPPL-9 and Zepbound SUPPL-2 ^{[3] [4]}. Both labels also flag January 2026 updates to their administration sections ^{[1] [2]}.

Both labels warn never to share a KwikPen between patients, even if the pen needle is changed ^{[1] [2]}.

How much do Mounjaro and Zepbound cost?

Current prices have to be checked on Lilly’s own pages, which are updated as terms change. Lilly publishes brand-specific cost pages at pricinginfo.lilly.com/mounjaro and pricinginfo.lilly.com/zepbound ^{[12] [13]}, and its self-pay channel LillyDirect maintains separate Mounjaro and Zepbound product pages ^{[8] [9]}. Zepbound savings-program terms are published separately by Lilly ^[14], and Mounjaro savings and coverage information sits on mounjaro.lilly.com ^[15]. Lilly has also issued a news release announcing lowered prices for Zepbound single-dose vials ^[22].

For any current figure — list price, LillyDirect self-pay price, savings-card copay, caps, exclusions or expiration dates — check those pages directly, and note which kind of price each one states, since a self-pay price is not the same thing as a list price.

Do they have the same warnings and side effects?

The boxed warning and contraindications are the same on both labels. Both carry the same boxed warning: tirzepatide causes thyroid C-cell tumors in rats, and it is unknown whether it causes thyroid C-cell tumors, including medullary thyroid carcinoma, in humans, as the human relevance of tirzepatide-induced rodent thyroid C-cell tumors has not been determined ^{[1] [2]}. Both are contraindicated in people with a personal or family history of medullary thyroid carcinoma, in people with Multiple Endocrine Neoplasia syndrome type 2, and in anyone with known serious hypersensitivity to tirzepatide or the product’s excipients ^{[1] [2]}.

The warnings lists match in kind, though not word for word: severe gastrointestinal reactions (not recommended in severe gastroparesis), acute kidney injury due to volume depletion, acute gallbladder disease, acute pancreatitis, hypersensitivity reactions including anaphylaxis and angioedema, hypoglycemia when combined with insulin or an insulin secretagogue, monitoring for diabetic retinopathy progression, and pulmonary aspiration during general anesthesia or deep sedation ^{[1] [2]}. One wording difference: the Mounjaro label’s retinopathy warning covers patients with a history of diabetic retinopathy, while the Zepbound label’s covers patients with type 2 diabetes mellitus, and the section numbering differs between the two labels ^{[1] [2]}. Both drugs delay gastric emptying and can affect the absorption of other oral medications ^{[1] [2]}.

The common side-effect lists differ, reflecting the different populations studied. Adverse reactions reported in 5% or more of Zepbound-treated patients were nausea, diarrhea, vomiting, constipation, abdominal pain, dyspepsia, injection site reactions, fatigue, hypersensitivity reactions, eructation, hair loss, and gastroesophageal reflux disease ^[1]. For Mounjaro, the list was nausea, diarrhea, decreased appetite, vomiting, constipation, dyspepsia, and abdominal pain ^[2]. In the SURPASS-CVOT trial, the most common adverse events with Mounjaro were gastrointestinal, generally mild to moderate, and occurred mostly during dose escalation ^[6].

What label changes happened in 2025 and 2026?

Both labels have been updated repeatedly, and some changes are ones readers ask about directly.

The Zepbound label flags these recent major changes: Severe Gastrointestinal Adverse Reactions (5.2) dated 02/2026; Suicidal Behavior and Ideation — Removed — dated 02/2026; Never Share a Zepbound KwikPen Between Patients (5.10) dated 01/2026; Diabetic Retinopathy Complications in Patients with Type 2 Diabetes Mellitus (5.8) dated 08/2026; and Dosage and Administration (2.4) dated 01/2026 ^[1]. On the FDA side, Zepbound supplement SUPPL-42 (Labeling-Package Insert) has an action date of February 25, 2026, and SUPPL-41 (Efficacy-Labeling Change With Clinical Data) has an action date of August 26, 2026 ^{[4] [16]}.

The Mounjaro label flags these recent major changes: Severe Gastrointestinal Adverse Reactions (5.6) dated 12/2025; Diabetic Retinopathy Complications in Patients with a History of Diabetic Retinopathy (5.7) dated 08/2026; and Never Share a Mounjaro KwikPen Between Patients (5.10) dated 01/2026 ^[2].

The current labels on DailyMed were updated August 28, 2026 for Zepbound and August 27, 2026 for Mounjaro ^{[1] [2]}.

What studies back each brand’s main use?

Mounjaro’s cardiovascular indication rests on SURPASS-CVOT (NCT04255433), which randomized 13,299 participants 1:1 across 640 sites in 30 countries to Mounjaro (15 mg or maximum tolerated dose) or Trulicity (dulaglutide) 1.5 mg weekly ^[6]. Over a median follow-up of 210.1 weeks — about four years — Mounjaro was non-inferior to dulaglutide for the MACE-3 composite of cardiovascular death, heart attack, or stroke; superiority was not established ^[6]. Lilly reported an 8% lower rate of cardiovascular death, heart attack or stroke, with a hazard ratio of 0.92 (95.3% CI 0.83–1.01) ^[6].

Zepbound’s sleep apnea indication rests on SURMOUNT-OSA (NCT05412004), which randomized 469 participants 1:1 to Zepbound (maximum tolerated dose of 10 mg or 15 mg) or placebo, measuring change in the apnea-hypopnea index at 52 weeks ^[7]. Participants not on PAP therapy had 25 fewer breathing disruptions per hour with Zepbound versus 5 with placebo; those on PAP had 29 fewer versus 6 ^[7]. After one year, 42% of the Zepbound group and 50% of the Zepbound-plus-PAP group reached remission or mild, non-symptomatic OSA, versus 16% and 14% on placebo ^[7]. Weight loss averaged 45 lbs (18% of body weight) with Zepbound and 50 lbs (20%) with Zepbound plus PAP, versus 4 lbs (2%) and 6 lbs (2%) on placebo ^[7].

Why do UK websites call Mounjaro a weight-loss drug?

Because the UK regulator did. The UK’s MHRA has authorized Mounjaro (tirzepatide) for weight management and weight loss ^[17]. The U.S. label carries no weight-management indication for Mounjaro ^[2]. So a UK news story about Mounjaro as a weight-loss drug and a U.S. pharmacy label for Mounjaro are describing two different regulatory situations for the same molecule.

How do you avoid counterfeit or unapproved tirzepatide?

Lilly operates scan.lilly.com, where the authenticity of Zepbound and Mounjaro medication can be checked, and maintains a counterfeit-medicine identification page at lilly.com/medicines/safety/counterfeit ^{[18] [19]}. The only FDA-approved presentations of tirzepatide are the subcutaneous injection forms listed on the two labels and in FDA’s drug database ^{[1] [2] [3] [4]}. FDA has also posted a declaration document regarding tirzepatide shortage status; its current wording and date should be confirmed on the FDA page before relying on it ^[20].

What should you expect at the pharmacy counter?

The brand follows the approved indication: type 2 diabetes or cardiovascular risk in type 2 diabetes corresponds to Mounjaro; obesity or OSA with obesity corresponds to Zepbound ^{[1] [2]}. Each brand carries its own NDC codes and its own approved uses ^{[1] [2]}.

Suspected adverse reactions can be reported to Eli Lilly at 1-800-LillyRx (1-800-545-5979) or to FDA at 1-800-FDA-1088 or www.fda.gov/medwatch ^{[1] [2]}. Any question about which brand or dose fits a specific situation belongs with a healthcare provider — the information here describes what the labels state, nothing more.

Sources

1. National Library of Medicine, DailyMed. ZEPBOUND (tirzepatide) injection, solution.
2. National Library of Medicine, DailyMed. MOUNJARO (tirzepatide) injection, solution.
3. US Food and Drug Administration. Drugs@FDA: New Drug Application 215866, Eli Lilly and Co.
4. US Food and Drug Administration. Drugs@FDA: New Drug Application 217806, Eli Lilly and Co.
5. US Food and Drug Administration. Supplement approval letter, NDA 215866/S-039, Mounjaro (tirzepatide) injection.
6. Eli Lilly and Company. FDA approves Lilly’s Mounjaro (tirzepatide) to reduce cardiovascular risk in adults with type 2 diabetes. August 28, 2026.
7. Eli Lilly and Company. FDA approves Zepbound (tirzepatide) as the first and only prescription medicine for moderate-to-severe obstructive sleep apnea in adults with obesity. December 20, 2024.
8. Eli Lilly and Company, LillyDirect. Authentic Zepbound (tirzepatide) shipped to you.
9. Eli Lilly and Company, LillyDirect. Authentic Mounjaro (tirzepatide) shipped to you.
10. US Food and Drug Administration. Supplement approval letter, NDA 217806/S-002, Zepbound KwikPen (tirzepatide) injection.
11. US Food and Drug Administration. Supplement approval letter, NDA 215866/S-009, Mounjaro KwikPen (tirzepatide) injection.
12. Eli Lilly and Company. Mounjaro cost information, with or without insurance.
13. Eli Lilly and Company. Zepbound cost information, with or without insurance.
14. Eli Lilly and Company. Zepbound (tirzepatide): full terms and conditions.
15. Eli Lilly and Company. Savings and coverage, Mounjaro (tirzepatide).
16. US Food and Drug Administration. Supplement approval letter, NDA 217806/S-042, Zepbound (tirzepatide) injection.
17. UK Government, Medicines and Healthcare products Regulatory Agency. MHRA authorises diabetes drug Mounjaro (tirzepatide) for weight management and weight loss.
18. Eli Lilly and Company. Check the authenticity of your Zepbound (tirzepatide) and Mounjaro (tirzepatide) medication.
19. Eli Lilly and Company. Identify real Lilly medicine: protect yourself from counterfeit and unsafe, mass compounded products.
20. US Food and Drug Administration. Declaratory order: resolution of shortages of tirzepatide injection products (Mounjaro and Zepbound). December 19, 2024.
21. US Food and Drug Administration. Supplement approval letter, NDA 215866/S-044 and S-045, Mounjaro (tirzepatide) injection.
22. Eli Lilly and Company. Lilly lowers the price of Zepbound (tirzepatide) single-dose vials. December 1, 2025.