Cagrilintide with retatrutide: what the evidence covers

Cagrilintide is a long-acting amylin analogue developed by Novo Nordisk. Retatrutide is a single molecule from Eli Lilly that acts on three receptors: GIP, GLP-1 and glucagon ^[2]. They come from competing companies, act on different hormone systems, and neither is approved anywhere.

"Cagri reta" and "cagri reta blend" are shorthand from online forums and peptide sellers for taking both, either as two injections or premixed in one vial. Neither drug is sold legitimately outside clinical trials, so what is in such a vial has not been checked by any regulator. One 2026 case report describes a person with type 1 diabetes whose impending diabetic ketoacidosis was complicated by retatrutide bought online ^[3].

The combination that was tested is different: cagrilintide with semaglutide, as CagriSema, a fixed-dose product studied in phase 3 against each of its parts. The sister page on cagrilintide with tirzepatide covers the other untested pairing people ask about.

In Nature Metabolism in September 2026, researchers gave diet-induced obese male rats daily injections of retatrutide and cagrilintide together. The combination reduced body weight and food intake in a dose-dependent way, by more than either drug alone at matched molar doses and by more than comparator combinations built on semaglutide or tirzepatide ^[1].

Three details limit what that means for people. The animals were rats, all male. They were dosed daily, not weekly as in human trials of either drug. And the authors frame the result as support for "five-receptor polypharmacology" and as guidance for designing future single-molecule drugs ^[1], which is a statement about drug design, not about two injections taken together.

For comparison, before cagrilintide and semaglutide reached phase 3 together, Novo Nordisk ran a phase 1b trial in 96 people that paired six cagrilintide doses with semaglutide 2.4 mg, co-escalated in 4-week intervals over 16 weeks, and measured safety and drug levels for each combination ^[4]. No equivalent study exists for cagrilintide with retatrutide.

The table lists what each drug's trials administered, in its own programme. The rows are not a schedule and cannot be merged into one.

Two things follow. First, no dose is established for the two drugs together, for any purpose, by any trial. Second, the trial doses above were of each manufacturer's own product, given under monitoring; they say nothing about the contents of a vial bought online. The cagrilintide calculator does the volume arithmetic for the trial doses of cagrilintide alone; it has no combination mode because there is no combination evidence to build one on.

Both drugs reduce appetite, through overlapping brain circuits, and both cause their main side effects in the gut. The one combination with complete phase 3 data shows what that overlap does. In REDEFINE 1, cagrilintide 2.4 mg alone produced 11.8% weight loss and semaglutide 2.4 mg alone 16.1%, but the two together produced 22.7%, not the sum ^[7].

Tolerability overlaps too. In retatrutide's phase 2 trial, gastrointestinal adverse events were dose-related and were partly reduced by starting at 2 mg rather than 4 mg ^[2]. In TRIUMPH-1, 11.3% of people on retatrutide 12 mg stopped because of adverse events, against 4.9% on placebo ^[8]; in TRIUMPH-3, in people with heart disease, the figure on 12 mg was 13.5% ^[10]. Adding a second appetite drug on top of a full retatrutide dose has not been measured at all, which is why its effect on nausea, vomiting, dehydration or discontinuation is unknown rather than merely uncertain.

The search "what is cagrilintide retatrutide for men" has no human answer for the combination. The rat study used only males ^[1], which is the one place "for men" and this pairing meet in the literature.

For retatrutide alone, the phase 2 trial deliberately enrolled roughly equal numbers of men and women (51.8% men) ^[2]. In its 8 mg (initial dose 4 mg) and 12 mg groups, women lost more weight on average than men: 28.5% and 26.6% against 19.8% and 21.9% ^[2]. The authors did not establish why. Lilly's phase 3 announcements report no results by sex ^[8][10].

For cagrilintide, the trials with the most men were CagriSema trials, not cagrilintide alone: REDEFINE 5 in Japan and Taiwan enrolled 68% men ^[11]. Its abstract reports no separate result for men. Nothing published shows the combination with retatrutide working differently, better or worse, in men.

Retatrutide is not approved in any country. Results Lilly has announced from its phase 3 programme include:

• TRIUMPH-1, 2,339 adults with obesity or overweight, 80 weeks: 19.0%, 25.9% and 28.3% weight loss on 4, 9 and 12 mg ^[8].
• TRIUMPH-2, 1,152 adults with type 2 diabetes, 80 weeks: 12.7%, 19.1% and 20.8% on 4, 9 and 12 mg, against 4.0% on placebo ^[10].
• TRIUMPH-3, 1,949 adults with severe obesity and heart disease, 80 weeks: 21.6% and 22.6% on 9 and 12 mg, against 3.2% on placebo; the cardiovascular event comparisons did not reach statistical significance ^[10].

In July 2026 Lilly said it was completing the manufacturing (CMC) data package and planned to submit retatrutide for U.S. approval in Q1 2027 ^[10]. Cagrilintide's furthest-advanced form is CagriSema, which Novo Nordisk submitted to the FDA in December 2025 ^[12]; cagrilintide itself is not approved alone or in any combination. So the pairing searched as "cagri reta" combines one drug awaiting filing with another awaiting a decision, and has never been tested as a pair. The new weight-loss drugs guide places both in the wider pipeline.