What is the core difference between cagrilintide and retatrutide?
The two work through completely different hormone systems. Cagrilintide is a long-acting analog of amylin, a hormone co-secreted with insulin. It acts as an agonist at the amylin receptors (AMY1R and AMY3R) — which are the calcitonin receptor paired with accessory RAMP proteins — and signals in the hindbrain to promote satiety and slow gastric emptying. Retatrutide takes the incretin route instead: it is a single molecule that activates three receptors at once — GIP, GLP-1, and glucagon.
That difference in target explains why they are studied differently. Because amylin and GLP-1 act on complementary pathways, cagrilintide has mostly been developed in combination with the GLP-1 agonist semaglutide, a fixed-dose pairing called CagriSema. Retatrutide, by contrast, is being advanced as a standalone triple agonist, with the glucagon arm adding a mechanism — increased energy expenditure and reduced liver fat — that neither amylin nor GLP-1 contributes on its own.
The most important point for anyone reading today, though, is that both are investigational. Neither cagrilintide nor retatrutide is approved by the FDA, and the only lawful way to receive either is enrollment in a clinical trial.
Which produced more weight loss in clinical trials?
In its Phase 2 monotherapy trial (Lancet, 2021), once-weekly cagrilintide at the 4.5 mg dose produced a mean weight reduction of about 10.8% at 26 weeks, versus 3.0% for placebo, and it outperformed the active comparator liraglutide 3.0 mg (about 9.0%). Retatrutide, in its Phase 2 obesity trial (NEJM, 2023), produced a much larger mean reduction of roughly 24.2% at the 12 mg dose over 48 weeks — among the highest figures reported for any pharmacological agent.
It is essential not to over-read that gap. These came from different trials, with different doses, durations, and patient populations, and they were never compared head-to-head. The cagrilintide figure is for the amylin analog alone; in practice cagrilintide is being developed as the CagriSema combination, where the addition of semaglutide pushed weight loss substantially higher in later trials. Comparing a single-agent Phase 2 number against a triple agonist is not a like-for-like contest.
How do the side effects compare?
Both compounds are dominated by gastrointestinal side effects, which is typical of drugs acting on appetite and gut-hormone pathways. For cagrilintide, nausea was the most commonly reported adverse event in its Phase 2 trial, and like other agents in this space the GI effects were dose-dependent and tended to ease with gradual dose escalation. Retatrutide trials reported the familiar cluster — nausea, diarrhea, vomiting, and constipation — also dose-dependent.
Retatrutide trials additionally noted dose-dependent increases in heart rate, a signal linked to its glucagon-receptor activity that is being watched closely in Phase 3. For both compounds the longer-term safety picture is, by definition, still incomplete: neither has accumulated the post-market safety database that an approved medicine carries. That asymmetry — investigational evidence on both sides — is itself a meaningful part of the comparison.
Are cagrilintide and retatrutide approved or legal?
Neither is FDA-approved. Cagrilintide has no standalone approval; Novo Nordisk has filed it only as the combination CagriSema (cagrilintide plus semaglutide), with the New Drug Application submitted in December 2025 and FDA review expected during 2026 — meaning that as of this writing it is filed but not approved. Retatrutide remains in Phase 3 of Eli Lilly's TRIUMPH program and is likewise not approved.
For both, the only lawful route to access is a clinical trial. Material sold online as "research" cagrilintide or retatrutide is explicitly labeled not for human use, is unregulated for identity, purity, and sterility, and sits outside the approved supply chain. For athletes there is an added line: as non-approved peptide agents, both fall under the World Anti-Doping Agency framework (non-approved substances, S0, and peptide hormones/mimetics, S2) and should be treated as prohibited in tested sport. Any decision about either compound belongs with a licensed clinician.
Tracking either compound on PeptidePanel
Whichever agent a clinician is overseeing, the monitoring discipline is the same: log doses, watch the biomarkers that matter (weight trend, HbA1c, lipids, liver enzymes, heart rate), and catch side effects early. PeptidePanel is the neutral tracking layer for that — it records the protocol your clinician sets, charts your bloodwork against reference ranges, and reminds you when a dose or a lab is due.
PeptidePanel does not sell, source, supply, endorse, or prescribe any compound, and nothing here is medical advice. Both compounds on this page are investigational and of unverified long-term safety in humans. The tool is for record-keeping on protocols a qualified prescriber has put you on — not a way to obtain anything.