Mounjaro and Zepbound are one drug sold under two names for two sets of indications. The labels were revised the same month (August 2026) and read almost identically for pages at a time. The differences are real, though, and they are all in the places people do not look.
Where they are identical
| Mounjaro (NDA 215866) | Zepbound (NDA 217806) | |
|---|---|---|
| Strengths | 2.5, 5, 7.5, 10, 12.5, 15 mg | 2.5, 5, 7.5, 10, 12.5, 15 mg |
| Start | 2.5 mg weekly, 4 weeks | 2.5 mg weekly, 4 weeks |
| Steps | +2.5 mg after 4 or more weeks | +2.5 mg after 4 or more weeks |
| Maximum | 15 mg adults; 10 mg age 10 to 17 | 15 mg; not established under 18 |
| Missed dose | Within 96 hours, else skip | Within 96 hours, else skip |
| Day change | 72 hours minimum | 72 hours minimum |
| Presentations | Single-dose pen and vial, multi-dose vial, KwikPen | Single-dose pen and vial, multi-dose vial, KwikPen |
Both labels revised 08/2026. Concentrations, storage limits and the boxed warning are also identical.
The 0.5 mL single-dose pens and vials, the 2.4 mL four-dose multi-dose vials and KwikPens, and the six concentrations from 4.17 to 25 mg/mL are the same across both products. So are the storage rules (21 days at room temperature for single-dose, 30 days or four doses for multi-dose), the boxed warning on thyroid C-cell tumors, and the two contraindications.
Where they differ
Indications. Mounjaro: an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients aged 10 and older with type 2 diabetes, and to reduce the risk of major adverse cardiovascular events in adults with type 2 diabetes at high cardiovascular risk. Zepbound: to reduce excess body weight and maintain weight reduction long term in adults with obesity or overweight plus a comorbidity, and to treat moderate to severe OSA in adults with obesity.
Approval dates. Mounjaro, May 13, 2022. Zepbound, November 8, 2023, with OSA added December 20, 2024.
Escalation language. Mounjaro says to increase "if additional glycemic control is needed". Zepbound says to increase according to the schedule and to choose a maintenance dose on response and tolerability, naming 5, 10 and 15 mg for weight and 10 and 15 mg for OSA. Mounjaro names no maintenance doses; the target is glycemic.
Pediatric use. Mounjaro is approved from age 10 for type 2 diabetes, with a 10 mg maximum in that group. Zepbound is not established in pediatric patients.
The adverse reaction tables. This is the difference that misleads most people. Mounjaro's Table 1 pools SURPASS-1 and SURPASS-5 in adults with type 2 diabetes (mean exposure 36.6 weeks) and lists reactions at 5% or more: nausea 12%, 15%, 18% at 5, 10, 15 mg versus 4% on placebo; diarrhea 12%, 13%, 17% versus 9%; decreased appetite 5%, 10%, 11% versus 1%; vomiting 5%, 5%, 9% versus 2%; constipation 6%, 6%, 7% versus 1%. Zepbound's Table 1 pools SURMOUNT-1 and SURMOUNT-2 (up to 72 weeks) at a 2% threshold: nausea 25%, 29%, 28% versus 8%; diarrhea 19%, 21%, 23% versus 8%; vomiting 8%, 11%, 13% versus 2%; constipation 17%, 14%, 11% versus 5%. Same drug, roughly double the nausea rate. The populations, trial lengths and reporting thresholds differ, so the tables are not comparable, and the label says so in its opening sentence about clinical trial rates. Any GI reaction: Mounjaro 37.1%, 39.6%, 43.6% versus 20.4%; Zepbound 56% at every dose versus 30%. The side-effect explorer lets you switch between the two tables.
Diabetes-specific warnings. Both labels warn about hypoglycemia with insulin or secretagogues and about diabetic retinopathy complications. In practice they bear on Mounjaro's population; the Zepbound label restricts the retinopathy warning to patients with type 2 diabetes.
Cardiovascular outcomes. Mounjaro's label includes the MACE indication and refers to a cardiovascular outcomes trial of 6,647 adults with type 2 diabetes and established cardiovascular disease; its section 6.1 reports higher rates of decreased appetite (17%), constipation (13%), vomiting (12%), abdominal pain (10%) and fatigue (10%) in that trial. Zepbound's label has no cardiovascular outcomes indication.
Which one you get
Prescribers and insurers usually decide this by diagnosis: type 2 diabetes leads to Mounjaro, obesity or OSA to Zepbound. Self-pay pricing is a Zepbound story; Lilly's published vial and KwikPen cash prices, tracked on the self-pay price page, are for Zepbound, and Lilly publishes Mounjaro's list price separately on its pricing site. Compounded tirzepatide is a third thing: not FDA approved and not interchangeable with either. For the semaglutide equivalents of both labels, the sister site Semaglutide Hub has the Ozempic versus Wegovy version of this page.
Questions people ask
Can I use Mounjaro for weight loss?
Mounjaro's approved indications are type 2 diabetes and cardiovascular risk reduction in adults with type 2 diabetes. Zepbound carries the weight-reduction and OSA indications. Prescribing outside a label is a matter between a prescriber, a patient and, usually, an insurer; the label itself does not address it.
Are Mounjaro and Zepbound interchangeable at the pharmacy?
They are the same molecule at the same strengths, but they are separate approved products with separate indications, and the Zepbound label states it should not be used with Mounjaro or other GLP-1 receptor agonists. A pharmacist cannot substitute one for the other without a new prescription. Compounded tirzepatide is interchangeable with neither.
Sources
- Zepbound (tirzepatide) prescribing information, Eli Lilly, DailyMed set id 487cd7e7-434c-4925-99fa-aa80b1cc776b, revised 08/2026 Accessed September 4, 2026.
- Mounjaro (tirzepatide) prescribing information, Eli Lilly, DailyMed set id d2d7da5d-ad07-4228-955f-cf7e355c8cc0, revised 08/2026 Accessed September 4, 2026.
- Eli Lilly press release, FDA approves Lilly's Mounjaro, May 13, 2022 Accessed September 4, 2026.
- FDA press announcement, FDA Approves New Medication for Chronic Weight Management, November 8, 2023 Accessed September 4, 2026.
Canonical URL: https://formblendstirzepatide.com/compare/mounjaro-vs-zepbound. Written by the FormBlends editorial team. This page is educational and is not medical advice; see the medical disclaimer.