CagriSema(Cagrilintide + Semaglutide)
The only stack anyone tested.
Every other combination on this site rests on reasoning. This one went through a 3,417-person trial that compared it against each of its two compounds taken alone. It worked, and it delivered 88% of what the two compounds should have added up to. That shortfall is the only real measurement anyone has of whether stacking adds up.
They also gave each compound on its own.
Testing a combination properly means running it against each of its parts. Against nothing at all is a lower bar. Otherwise a good result might be coming entirely from one compound and the other is along for the ride.
REDEFINE 1 did that. 3,417 adults over 68 weeks, split by chance into four groups: the combination, semaglutide alone, cagrilintide alone, and a placebo, meaning a dummy injection with no drug in it. Splitting by chance is what makes the four groups comparable, and each group is called an arm.[3] Published in the New England Journal of Medicine in June 2025.[1]
No other combination discussed in peptide communities has been through anything like this, and most have been through nothing at all.
Mean weight loss at 68 weeks
Figures below count only the people who stayed on treatment for the full 68 weeks.[5]
The combination beat both compounds alone, and beat them clearly. Adding a second appetite pathway to semaglutide moved average weight loss from 16.1% up to 22.7%, a gap of 6.6 percentage points. That figure is the distance between 16.1 and 22.7, and it does not mean 6.6% more weight came off.
You will see two different headline numbers for this trial, and both are correct. 22.7% is what happened among people who stayed on the drug. 20.4% counts everyone who started, including those who stopped early or dropped out.[5] The first answers what the drug does. The second answers what happens to a group of real people handed a prescription. Coverage that quotes one without saying which is leaving out the part that matters.
A mean of 22.7% says nothing about your chances.
How many people cleared each threshold is the part worth reading.
Roughly one in eight people saw less than 5% come off after 68 weeks on the most effective combination yet tested. Most coverage of this drug leaves that number out.
Two sources disagree here and one of them is wrong. One commercial summary reports that 40.4% of participants lost 25% or more.[7] Another reports 43% losing 20% or more.[8] Those cannot both hold: almost everyone clearing 20% would also have to clear 25%, which no weight loss trial has ever shown. We have not resolved which figure is the error, and neither is quoted from the primary paper.
Two compounds did not add up to the sum of their parts.
Strip out the placebo effect and compare what each arm actually contributed.
Better than either compound on its own, and roughly three percentage points short of stacking them arithmetically. Two appetite pathways overlap more than the mechanism story suggests they should.
No other hard measurement of this exists. And it comes from the pairing with the cleanest separation of any on the site: a gut hormone and a pancreatic one, different receptors, different organs.
If the best-separated pair in the category lands at 88% of additive, combinations with overlapping mechanisms have no reason to do better. A stack of four growth hormone compounds acting across two receptors is not going to deliver four compounds worth of effect. Nobody has measured that, and this is the closest thing to a number we have.
Read against your own stack, it cuts in a useful direction. Two compounds on separate pathways gave most of what addition predicted, which is a real result and better than nothing. The shortfall showed up anyway, in the cleanest case available, before anyone got to three or four compounds. Each one you add is buying a smaller share of what it promises than the one before it.
It cleared the bar it was measured against, and missed two others.
Novo Nordisk had guided to roughly 25% weight loss. The trial returned 22.7% on the adherent analysis and 20.4% counting everyone regardless of adherence.[5] The result was widely reported as a disappointment despite being a clear win over placebo.
REDEFINE 4 compared CagriSema against tirzepatide 15 mg in 809 adults over 84 weeks. CagriSema reached about 23% and failed to show it was no worse than tirzepatide, a single-molecule drug.[4]
Both findings point the same direction. A properly tested two-compound combination matched, and did not beat, a well-designed single compound. Adding a second pathway does not automatically beat choosing a better first one.
A second trial, REDEFINE 2, ran the same combination in 1,206 adults who had type 2 diabetes alongside obesity. Weight loss there was 15.7% against 3.1% on placebo, noticeably less than in people without diabetes.[2] Weight comes off more slowly in type 2 diabetes across this whole drug class, so the gap is expected. It is worth knowing before comparing yourself to the headline figure.
Four in five had gut symptoms.
Nausea, vomiting, constipation and diarrhoea. Mostly mild to moderate, and easing over time, which is what the GLP-1 class does generally.[2] The placebo rate was already close to 40%, so the share attributable to the drug is smaller than the headline number suggests.
Both compounds slow digestion, and that is part of how each one works. Running two compounds that both do it is the clearest example on this site of side effects adding up instead of cancelling out.
The tested product is not what people are buying.
CagriSema is one injection, taken weekly, with both compounds fixed in it at a set ratio. It is investigational. The trial results describe that product and nothing else.
What circulates in peptide communities is the two compounds bought separately from research chemical vendors and combined by the buyer. What REDEFINE 1 tested was a different thing, and the trial results do not transfer to it. Semaglutide is FDA approved in its own right. Cagrilintide is not approved anywhere, in any form.
Novo Nordisk filed a New Drug Application with the FDA on 18 December 2025, and a first decision is expected in late 2026.[9] As of now CagriSema is approved by no regulator anywhere in the world, and no filing has been publicly confirmed in the EU, the UK or Canada. If the FDA approves, it becomes prescribable. If it issues a Complete Response Letter asking for more data, the timeline extends by a year or more.
What people ask about CagriSema
Is CagriSema approved yet?
No. Novo Nordisk filed with the FDA on 18 December 2025 and a first decision is expected in late 2026. It is approved by no regulator anywhere in the world, and no filing has been publicly confirmed in the EU, the UK or Canada.
How much weight did people lose on CagriSema?
In REDEFINE 1, an average of 22.7% of body weight over 68 weeks among people who stayed on treatment, or 20.4% counting everyone who started. Semaglutide alone reached 16.1% in the same trial and placebo reached 2.3%. In people with type 2 diabetes, in REDEFINE 2, the figure was 15.7%.
Is CagriSema better than tirzepatide?
It did not beat it. REDEFINE 4 compared the two directly in 809 adults over 84 weeks and CagriSema failed to show it was even no worse than tirzepatide 15 mg. A two-compound combination matched, and did not beat, a single molecule.
Is buying cagrilintide and semaglutide separately the same as CagriSema?
No. CagriSema is a fixed-dose combination developed as a single once-weekly injection, and the trial results describe that product. Two vials bought from research chemical vendors and combined by the buyer is a different thing, and the trial results do not transfer to it. Semaglutide has its own FDA approval. Cagrilintide has none, in any country.
What are the side effects?
Gastrointestinal symptoms, mostly nausea, vomiting, constipation and diarrhoea, were reported by 79.6% of people on CagriSema against 39.9% on placebo. Most were mild to moderate and eased over time. Both compounds slow digestion, so running them together stacks that effect rather than cancelling it.
Does stacking two peptides double the effect?
No, and this trial is the only place anyone has measured it. Above placebo, semaglutide contributed 13.8 points and cagrilintide 9.5. Simple addition predicts 23.3. The combination delivered 20.4, which is 88% of additive. That shortfall showed up in the cleanest-separated pairing available, so combinations with overlapping mechanisms have no reason to do better. See how the other stacks compare.
Every reference carries how it was read.
Unusually for this section, the primary evidence here is a peer-reviewed phase 3 trial. Most pages in this section rest on preprints and vendor claims.
- 01Davies et al., REDEFINE 1, New England Journal of Medicine, published 22 June 2025. PMID 40544433.
- 02REDEFINE 2 results, 1,206 adults with type 2 diabetes: 15.7% against 3.1% placebo. NCT05394519" rel="nofollow noopener" target="_blank">NCT05394519. Presented at ADA Scientific Sessions, published in NEJM.
- 03REDEFINE 1 registration, ClinicalTrials.gov NCT05567796. 3,417 adults, 68 weeks, four arms.
- 04REDEFINE 4, CagriSema against tirzepatide 15 mg, 809 adults, 84 weeks. NCT05394519 covers the REDEFINE 2 registration. Noninferiority not met.
- 05Group-by-group figures, the adherent and all-comers analyses, and the 79.6% gastrointestinal adverse event rate.
- 07Commercial summary reporting 40.4% of participants losing 25% or more of body weight.
- 08Clinical summary reporting the responder ladder: 88%, 75%, 62% and 43% at the 5, 10, 15 and 20 percent thresholds.
- 09Regulatory status: NDA filed 18 December 2025, first US decision expected late 2026, no approval anywhere as of September 2026.
- 06Peptide Decoding vendor pricing data, 12 September 2026. Single-compound vials only.