Tirzepatide is the first approved drug to activate two incretin receptors with one molecule. It reached the market as Mounjaro for type 2 diabetes in 2022, as Zepbound for weight in 2023, and has since added obstructive sleep apnea, a pediatric diabetes indication, and, on 27 August 2026, a cardiovascular risk-reduction indication. FormBlends has a longer narrative tirzepatide guide; this page is the reference entry.
Mechanism and receptor profile
The Mounjaro label describes tirzepatide as a GIP receptor and GLP-1 receptor agonist that selectively binds and activates both receptors, with a C20 fatty diacid moiety that enables albumin binding and prolongs the half-life. GIP (glucose-dependent insulinotropic polypeptide) is the other incretin hormone; on its own it is a weak drug, but combined with GLP-1 activity in one peptide it produced larger weight and HbA1c changes than the GLP-1 comparators tested. Why is still debated; the Science site covers the receptor biology.
FDA approvals, with dates
| Date | Product | What was approved | Record |
|---|---|---|---|
| 13 May 2022 | Mounjaro | New molecular entity, glycemic control in adults with type 2 diabetes | NDA 215866, original |
| 8 Nov 2023 | Zepbound | Chronic weight management in adults with obesity, or overweight plus a weight-related condition | NDA 217806, original |
| 20 Dec 2024 | Zepbound | Moderate to severe obstructive sleep apnea in adults with obesity | NDA 217806, S-013 (letter) |
| 19 Dec 2025 | Mounjaro | Pediatric patients aged 10 and older with type 2 diabetes; warnings aligned with the class | NDA 215866, S-039 (letter) |
| 26 Aug 2026 | Zepbound | SURPASS-CVOT data added to the label, including the retinopathy warning; no new indication | NDA 217806, S-041 (letter) |
| 27 Aug 2026 | Mounjaro | Reduction of major adverse cardiovascular events in adults with type 2 diabetes at high risk (SURPASS-CVOT); 2.5 mg may be used for ongoing glycemic control | NDA 215866, S-044 and S-045 (letter) |
Both products are supplied as single-dose pens, single-dose vials and multi-dose KwikPens in 2.5 to 15 mg strengths.
Dosing as the label states it
Start at 2.5 mg once weekly for four weeks, increase to 5 mg, then increase in 2.5 mg steps after at least four weeks on the current dose.
| Mounjaro | Zepbound | |
|---|---|---|
| Starting dose | 2.5 mg for 4 weeks | 2.5 mg for 4 weeks (not a maintenance dose) |
| Escalation | 5 mg, then +2.5 mg after at least 4 weeks if more glycemic control is needed | 5 mg, then +2.5 mg after at least 4 weeks to the maintenance dose |
| Maintenance | Since August 2026 the label allows 2.5 mg for ongoing glycemic control; otherwise 5 to 15 mg | 5, 10 or 15 mg for weight; 10 or 15 mg for obstructive sleep apnea |
| Maximum | 15 mg (adults); 10 mg (ages 10 to 17) | 15 mg |
| Missed dose | Take within 4 days (96 hours), otherwise skip | Take within 4 days (96 hours), otherwise skip |
| Changing the day | Allowed if at least 3 days (72 hours) between doses | Allowed if at least 3 days (72 hours) between doses |
Injection sites are abdomen, thigh, or the back of the upper arm when someone else injects. The Zepbound label says to consider a lower maintenance dose if the intended one is not tolerated.
Pivotal trials and their numbers
| Trial | Population and duration | Result | PubMed |
|---|---|---|---|
| SURMOUNT-1 | 2,539 adults with obesity or overweight, no diabetes; 72 weeks | Weight -15.0% (5 mg), -19.5% (10 mg), -20.9% (15 mg) vs -3.1% placebo; 91% on 15 mg lost 5% or more vs 35% | 35658024 |
| SURMOUNT-2 | 938 adults with obesity or overweight and type 2 diabetes; 72 weeks | Weight -12.8% (10 mg) and -14.7% (15 mg) vs -3.2% placebo | 37385275 |
| SURPASS-2 | Adults with type 2 diabetes on metformin; 40 weeks | HbA1c -2.01, -2.24, -2.30 points (5, 10, 15 mg) vs -1.86 with semaglutide 1 mg; weight differences -1.9, -3.6, -5.5 kg | 34170647 |
| SURMOUNT-OSA | Adults with moderate to severe sleep apnea and obesity; 52 weeks, two trials | Apnea-hypopnea index -25.3 and -29.3 events per hour vs -5.3 and -5.5 on placebo | 38912654 |
| SURPASS-CVOT | 13,299 adults with type 2 diabetes and cardiovascular disease | Primary endpoint 12.2% vs 13.1% with dulaglutide; hazard ratio 0.92 (95.3% CI 0.83 to 1.01); non-inferior, not superior | 41406444 |
SURPASS-CVOT is the trial behind the August 2026 indication. Note what it compared: tirzepatide against dulaglutide, an active GLP-1 drug with its own cardiovascular indication, not against placebo. The result was non-inferiority with a point estimate in tirzepatide's favour, and the label's retinopathy warning was revised on the strength of the same trial.
Adverse reactions from the label
| Adverse reaction | Placebo % | 5 mg % | 10 mg % | 15 mg % |
|---|---|---|---|---|
| Nausea | 8 | 25 | 29 | 28 |
| Diarrhea | 8 | 19 | 21 | 23 |
| Vomiting | 2 | 8 | 11 | 13 |
| Constipation | 5 | 17 | 14 | 11 |
| Abdominal pain | 5 | 9 | 9 | 10 |
| Dyspepsia | 4 | 9 | 9 | 10 |
| Injection site reactions | 2 | 6 | 8 | 8 |
| Fatigue | 3 | 5 | 6 | 7 |
| Hypersensitivity reactions | 3 | 5 | 5 | 5 |
| Eructation | 1 | 4 | 5 | 5 |
| Hair loss | 1 | 5 | 4 | 5 |
Discontinuation for adverse reactions: 4.8%, 6.3% and 6.7% for 5, 10 and 15 mg against 3.4% on placebo, mostly in the first months and mostly gastrointestinal. The Mounjaro diabetes pool (placebo n=235; 5, 10, 15 mg n=237, 240, 241) reports nausea 4%, 12%, 15%, 18%; diarrhea 9%, 12%, 13%, 17%; decreased appetite 1%, 5%, 10%, 11%; vomiting 2%, 5%, 5%, 9%.
Boxed warning and other warnings
The class boxed warning: thyroid C-cell tumors in rats at clinically relevant exposures, human relevance unknown, contraindicated with a personal or family history of medullary thyroid carcinoma or MEN 2. Section 5 lists severe gastrointestinal reactions, acute kidney injury from volume depletion, gallbladder disease, pancreatitis, hypersensitivity, hypoglycemia (with insulin or sulfonylureas, or in type 2 diabetes), diabetic retinopathy complications, and pulmonary aspiration under anaesthesia. Zepbound's label also warns that coadministration with other tirzepatide products or any GLP-1 receptor agonist is not recommended.
Status and manufacturer
Approved and marketed by Eli Lilly.
Where next
The next step in the same direction is retatrutide, which adds glucagon receptor activity. The comparison table sets tirzepatide beside semaglutide, and the approval timeline shows how quickly the indications have accumulated.
Questions people ask
What is the difference between Mounjaro and Zepbound?
The same tirzepatide from the same manufacturer, in two FDA applications. Mounjaro is approved for type 2 diabetes in adults and children 10 and older and, since 27 August 2026, to reduce major adverse cardiovascular events in adults with type 2 diabetes at high risk. Zepbound is approved for weight reduction and for moderate to severe obstructive sleep apnea in adults with obesity. Doses and escalation are the same.
Did tirzepatide beat semaglutide in a head-to-head trial?
In SURPASS-2, in adults with type 2 diabetes, all three tirzepatide doses lowered HbA1c more than semaglutide 1 mg weekly and produced 1.9 to 5.5 kg more weight loss. That trial did not use the 2.4 mg or 7.2 mg semaglutide doses approved for weight, so it does not settle the weight comparison.
Sources
- Drugs@FDA: NDA 215866 Mounjaro (approval 2022-05-13; supplements 39, 44 and 45) Accessed September 4, 2026.
- Drugs@FDA: NDA 217806 Zepbound (approval 2023-11-08; supplements 13 and 41) Accessed September 4, 2026.
- FDA approval letter, NDA 215866 S-044 and S-045 (cardiovascular indication; 2.5 mg for ongoing glycemic control), 27 August 2026 Accessed September 4, 2026.
- FDA approval letter, NDA 215866 S-039 (pediatric type 2 diabetes), 19 December 2025 Accessed September 4, 2026.
- FDA approval letter, NDA 217806 S-013 (obstructive sleep apnea), 20 December 2024 Accessed September 4, 2026.
- Mounjaro prescribing information, Eli Lilly, DailyMed set id d2d7da5d-ad07-4228-955f-cf7e355c8cc0 Accessed September 4, 2026.
- Zepbound prescribing information, Eli Lilly, DailyMed set id 487cd7e7-434c-4925-99fa-aa80b1cc776b Accessed September 4, 2026.
- Jastreboff AM et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med 2022. PubMed 35658024 Accessed September 4, 2026.
- Garvey WT et al. Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2). Lancet 2023. PubMed 37385275 Accessed September 4, 2026.
- Frias JP et al. Tirzepatide versus semaglutide once weekly in patients with type 2 diabetes (SURPASS-2). N Engl J Med 2021. PubMed 34170647 Accessed September 4, 2026.
- Malhotra A et al. Tirzepatide for the treatment of obstructive sleep apnea and obesity (SURMOUNT-OSA). N Engl J Med 2024. PubMed 38912654 Accessed September 4, 2026.
- Cardiovascular outcomes with tirzepatide versus dulaglutide in type 2 diabetes (SURPASS-CVOT). N Engl J Med 2026. PubMed 41406444 Accessed September 4, 2026.
Canonical URL: https://formblendsglp1s.com/agents/tirzepatide. Written by the FormBlends editorial team. This page is educational and is not medical advice; see the medical disclaimer.