This is the rarest and most useful kind of comparison in obesity medicine: a direct head-to-head trial. Most drug comparisons rely on cross-trial estimates, where different populations and protocols make the numbers only loosely comparable. CagriSema and tirzepatide were tested against each other in the same study, and the result was not what the coverage leading up to it had implied.
CagriSema is an investigational once-weekly combination of the amylin analog cagrilintide and the GLP-1 drug semaglutide. Tirzepatide is the approved dual GIP/GLP-1 agonist sold as Mounjaro and Zepbound. In the 84-week REDEFINE 4 trial, CagriSema produced substantial weight loss — but did not meet its primary endpoint of non-inferiority to tirzepatide.
At a glance
| CagriSema | Tirzepatide | |
|---|---|---|
| Drug class | Amylin analog + GLP-1 agonist (fixed-dose combination) | Dual GIP + GLP-1 receptor agonist (single molecule) |
| Brand names | None yet — investigational | Mounjaro, Zepbound |
| FDA status | Not approved; NDA filed Dec 2025, decision expected late 2026 | Approved for type 2 diabetes, weight management & obstructive sleep apnea |
| Head-to-head result (REDEFINE 4, 84 weeks) | ~23.0% weight loss | ~25.5% weight loss |
| Primary endpoint | Did not meet non-inferiority | Comparator arm |
| Dosing | Once weekly injection | Once weekly injection |
| Main side effects | Nausea, vomiting, diarrhea, constipation (GI-dominant) | Nausea, diarrhea, constipation (GI-dominant) |
| Availability | Clinical trials only | Prescription, widely available |
The bottom line
Bottom line: On the only direct evidence available, tirzepatide produced more weight loss than CagriSema — about 25.5% versus about 23.0% over 84 weeks in 809 adults with obesity, with CagriSema missing its non-inferiority endpoint. Two things are true at once: CagriSema delivers weight loss that would have been extraordinary by any pre-2020 standard, and it did not beat the incumbent. For anyone choosing today the question is moot, because CagriSema is not approved and tirzepatide is. If CagriSema is approved, its case will rest on individual response and tolerability rather than on average superiority.
Frequently asked questions
Is CagriSema better than Zepbound?
Not on the available evidence. In REDEFINE 4, the direct head-to-head trial, CagriSema produced about 23.0% weight loss versus about 25.5% for tirzepatide (Zepbound) over 84 weeks, and did not meet its primary endpoint of non-inferiority. Both produce large weight loss; tirzepatide produced more.
Why did CagriSema fail its head-to-head trial?
It did not fail to work — it failed to prove it was not worse than tirzepatide, which is what a non-inferiority endpoint tests. CagriSema produced roughly 23% weight loss, a large effect. It simply fell short of tirzepatide's roughly 25.5% by enough to miss the statistical threshold.
Can I get CagriSema instead of Zepbound?
No. CagriSema is investigational and not approved by the FDA, so it is not available by prescription. Tirzepatide is approved and available. Anything sold online as CagriSema is not the studied drug and is not quality-assured.
What is the difference in how they work?
CagriSema combines two separate molecules acting on two hormone systems: semaglutide on GLP-1 receptors and cagrilintide on amylin receptors. Tirzepatide is a single molecule that activates two incretin receptors, GIP and GLP-1. Different strategies for the same goal of engaging more than one appetite pathway.
References
Combined peer-reviewed sources from both peptide guides. Inclusion is not endorsement.
- Garvey WT, Blüher M, Osorto Contreras CK, et al. Coadministered Cagrilintide and Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2025. Peer-reviewed study
- Davies MJ, Bajaj HS, Broholm C, et al. Cagrilintide-Semaglutide in Adults with Overweight or Obesity and Type 2 Diabetes. N Engl J Med. 2025. Peer-reviewed study
- Frias JP, Deenadayalan S, Erichsen L, et al. Efficacy and safety of co-administered once-weekly cagrilintide with once-weekly semaglutide in type 2 diabetes: a phase 2 trial. Lancet. 2023. Peer-reviewed study
- Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med. 2022. Peer-reviewed study
- Frias JP, Davies MJ, Rosenstock J, et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes (SURPASS-2). N Engl J Med. 2021. Peer-reviewed study
- Jastreboff AM, le Roux CW, Stefanski A, et al. Tirzepatide for Obesity Treatment and Diabetes Prevention. N Engl J Med. 2025. Peer-reviewed study
- 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. Peer-reviewed study
- Zhao L, Cheng Z, Lu Y, et al. Tirzepatide for Weight Reduction in Chinese Adults With Obesity: The SURMOUNT-CN Randomized Clinical Trial. JAMA. 2024. Peer-reviewed study
- Loomba R, Hartman ML, Lawitz EJ, et al. Tirzepatide for Metabolic Dysfunction-Associated Steatohepatitis with Liver Fibrosis. N Engl J Med. 2024. Peer-reviewed study