01 What is Cagrilintide?
In plain English.
Cagrilintide is an experimental once-weekly injection developed by Novo Nordisk for obesity and metabolic disease. It is a lab-made copy of amylin, a hormone the pancreas releases alongside insulin after a meal to tell the body it has eaten enough. The natural hormone lasts minutes; cagrilintide has been engineered to last about a week, so it can be injected weekly. It is most often tested alongside semaglutide (Wegovy / Ozempic), and the combination is known as CagriSema.
It is currently investigational, meaning it is not available as a prescription medicine anywhere in the world (neither alone nor as CagriSema). The only legitimate route to receive it today is enrolment in a registered clinical trial. Anything labelled 'cagrilintide' on a research-chemical site is unregulated and unverifiable.
02 How it works
The simple version, then the science.
Cagrilintide copies what the body's own amylin does after a meal: it slows down how fast the stomach empties, suppresses the post-meal rise in glucagon (a hormone that pushes blood sugar up), and signals fullness to the brain. That is a different mechanism from semaglutide, which acts on GLP-1 receptors. Because the two pathways are independent, hitting both at once (as in CagriSema) appears to produce more appetite suppression and more weight loss than either alone.
Go deeper · the proposed mechanism
Cagrilintide is a long-acting acylated analogue of human amylin with high-affinity agonism at the calcitonin and amylin receptor subtypes (AMY1R, AMY2R, AMY3R, plus the calcitonin receptor itself). Albumin binding via a fatty-acid side chain extends the half-life to roughly one week, supporting once-weekly subcutaneous dosing. Functional effects include delayed gastric emptying, postprandial glucagon suppression, and central anorectic signalling via area postrema and hypothalamic amylin-responsive neurons. Combination with semaglutide is hypothesised to be additive because the GLP-1 and amylin receptor pathways converge on overlapping (but not identical) appetite circuits.
03 What it's used for
Each use graded by how strong the evidence actually is.
- ModerateObesity / weight loss (monotherapy)🔬 Phase 2 dose-finding trial (Lau et al., Lancet 2021; n=706) reported up to 10.8% mean weight loss at the 4.5 mg weekly dose at 26 weeks, with a dose-response across 0.3–4.5 mg. Cagrilintide alone is not being developed as a standalone weight-loss drug; the lead programme is the CagriSema combination.
- ModerateObesity (CagriSema combination)🔬 REDEFINE 1 (NEJM, 2025; n=3,417) reported ~22.7% mean weight loss at 68 weeks on cagrilintide 2.4 mg + semaglutide 2.4 mg, versus ~16.1% on semaglutide alone and ~11.8% on cagrilintide alone. Phase 3 read-out, not yet approved.
- ModerateType 2 diabetes (CagriSema combination)🔬 REDEFINE 2 (NEJM, 2025) tested CagriSema in adults with overweight/obesity and type 2 diabetes; weight loss and HbA1c reductions were larger than semaglutide alone. Phase 2 work in T2D (Frias et al., Lancet 2023) showed similar synergy with HbA1c and body weight.
- AnecdotalOnline "research chemical" weight-loss use💬 Cagrilintide vials and CagriSema "stacks" are sold by unregulated peptide vendors. Contents, purity, sterility and dose accuracy are unverifiable; there is no clinical oversight and no approved product to compare against.
04 What the evidence says
The evidence base is the most interesting one in obesity right now, but it is still preliminary. The phase 2 monotherapy trial (Lau et al., Lancet 2021) established dose-response and tolerability and produced mean weight loss up to ~10.8% over 26 weeks. A phase 1b combination study (Enebo et al., Lancet 2021) first showed the additive signal with semaglutide. The phase 2 combination work in type 2 diabetes (Frias et al., Lancet 2023) confirmed synergy on weight and HbA1c. The phase 3 REDEFINE 1 readout in 2025 (Garvey et al., NEJM) reported ~22.7% mean weight loss at 68 weeks on CagriSema, versus ~16.1% on semaglutide alone. Two honest caveats. First, the headline CagriSema number landed below the higher expectations set by earlier briefings, which moved Novo Nordisk's share price meaningfully on the day. Second, long-term safety beyond the trial window is unknown, and cagrilintide has never been tested at population scale. Until regulators review the full dossier, the right description is 'strong, on-label-quality phase 3 data for the combination, not yet approved'.
05 Dosing & administration
Reported in the literature, information not advice.
For context only. There is no approved cagrilintide or CagriSema product and no validated outpatient protocol. Trial protocols use once-weekly subcutaneous injection with a slow titration over several months (typically 0.25 mg, then stepping through 0.5, 1.0, 1.7 and 2.4 mg weekly) to manage gastrointestinal side effects; in the combination programme, semaglutide is titrated on the same schedule. Self-dosing from unregulated suppliers sits outside the boundary of established medicine and cannot be made safe by following a forum protocol.
06 Side effects & safety
Across phase 2 and phase 3 trials, the safety profile has looked broadly similar to other gut-hormone analogues. The most common adverse events are gastrointestinal (nausea, vomiting, diarrhoea, constipation, dyspepsia), typically worst during dose escalation and easing thereafter. Injection-site reactions are reported. Hypersensitivity reactions have been observed at higher rates than with semaglutide alone in some trials. Because amylin agonism delays gastric emptying, drugs that depend on rapid absorption may be affected. Pregnancy, breastfeeding, personal or family history of medullary thyroid cancer or MEN-2, severe gastrointestinal disease, and active pancreatitis are typical exclusions in trials of this class. Long-term safety beyond the longest published follow-up (~80 weeks for the REDEFINE programme) is not yet characterised. Quality of any non-trial "cagrilintide" sold online is unknown.
07 Where to buy (research use only)
Vetted on quality and transparency, not an endorsement to use.
08 Legal & regulatory status
- UKNot licensed by the MHRA. Available only via clinical trial participation. No legitimate UK supply outside trials.
- USNot FDA-approved. Phase 3 trials in progress; no compounding pathway because no approved cagrilintide product is on shortage.
- EUNot authorised by the EMA. Investigational only.
- SportCagrilintide is not named on the WADA Prohibited List, but as an unapproved investigational substance it is captured by category S0 ("Non-Approved Substances") and is prohibited at all times in tested sport.
09 Clinical studies & research
Primary sources. Read the science yourself.