What is CagriReta? 7 proven facts about the best dual-action weight loss injection.

What is CagriReta? It is the dual-action weight loss injection that produced some of the most significant clinical results in obesity medicine in 2025 — and it works through a fundamentally different mechanism from Mounjaro. CagriReta combines two proven active compounds in a single once-weekly injection: Cagrilintide, a long-acting amylin analogue, and Semaglutide, a GLP-1 receptor agonist. Together they target two separate hormonal pathways simultaneously, producing weight loss that significantly exceeds what either compound achieves alone.

The REDEFINE 1 Phase 3 trial — published in the New England Journal of Medicine in June 2025 — showed average weight loss of 20.4% over 68 weeks in adults without diabetes. Sixty percent of participants lost at least 20% of their body weight. These are remarkable results from a medication that takes a completely different route to weight loss than the GIP-based mechanisms in Mounjaro. Understanding what is CagriReta and how it works is essential for anyone deciding between the major weight loss injections available in the UK in 2026. The NHS healthy weight management guidance recommends a sustained, medically supported approach — CagriReta represents one of the most powerful tools in that framework.

What is CagriReta — the full explanation

So what is CagriReta exactly? It is the commercial name used at Mymetabolism for the combination of Cagrilintide (2.4mg) and Semaglutide (2.4mg) — known clinically as CagriSema and developed by Novo Nordisk. It is a fixed-dose combination product administered as a single once-weekly subcutaneous injection that delivers both active compounds simultaneously.

Cagrilintide is a long-acting amylin analogue — a synthetic version of amylin, a hormone naturally produced by the pancreas after eating that signals fullness and slows gastric emptying. Semaglutide is the GLP-1 receptor agonist found in both Ozempic and Wegovy — well established as one of the most effective weight loss mechanisms available. What is CagriReta in clinical terms? It is the first approved combination of an amylin analogue and a GLP-1 agonist in a single product — representing a genuinely new dual-mechanism approach to obesity pharmacotherapy.

In December 2025, Novo Nordisk submitted a New Drug Application to the FDA for CagriSema for weight management — based on the REDEFINE trial programme. FDA review is expected in 2026, with MHRA submission and UK approval anticipated to follow.

How does CagriReta work?

Understanding what is CagriReta requires understanding its two distinct mechanisms and why their combination produces superior results.

The Semaglutide component — GLP-1 receptor activation

Semaglutide works by activating GLP-1 receptors in the brain and digestive system — signalling fullness, slowing gastric emptying, and improving insulin sensitivity. This is the same mechanism that makes Ozempic and Wegovy effective. At the 2.4mg dose used in CagriReta, this is the same dose that produces 14.9% average weight loss in the STEP-1 trial as a standalone medication. In CagriReta, it provides the established, well-characterised GLP-1 foundation.

The Cagrilintide component — amylin and calcitonin receptor activation

Cagrilintide works through a fundamentally different pathway. Amylin is a hormone produced by beta cells in the pancreas alongside insulin after a meal. It signals to the brain that the stomach is full, slows gastric emptying, and reduces glucagon secretion. By activating both amylin and calcitonin receptors, Cagrilintide reduces appetite through a neural pathway entirely separate from GLP-1. This is what makes CagriReta mechanistically distinct from both Ozempic/Wegovy and Mounjaro — it combines GLP-1 with a non-GIP second pathway.

The synergistic effect of both pathways working simultaneously is greater than either alone — and the REDEFINE trial data proves it. Semaglutide alone produced 14.9% weight loss. Cagrilintide alone produced 11.5%. CagriReta together produced 20.4% — more than either compound would predict from simple addition, indicating genuine biological synergy between the two mechanisms.

CagriReta weight loss results — REDEFINE trial data

The REDEFINE programme is the most comprehensive Phase 3 evidence base for any weight loss combination product. Here is the complete data:

The REDEFINE 1 results were presented at the American Diabetes Association 85th Scientific Sessions in June 2025 and simultaneously published in the New England Journal of Medicine. Additional findings from the trial include a notable metabolic benefit: 88% of participants with prediabetes at baseline returned to normal blood glucose levels by week 68 — a remarkable metabolic outcome alongside the weight reduction, and one that positions CagriReta as particularly valuable for patients with prediabetes or metabolic syndrome.

CagriReta vs Mounjaro vs Ozempic — how they compare

Now that we understand what is CagriReta and how it works, here is how it compares directly to the other major weight loss injections available from Mymetabolism:

One striking figure in this comparison: while CagriReta and Mounjaro produce similar average weight loss (20.4% vs ~22%), CagriReta has a substantially higher proportion of patients achieving 20% or more body weight loss — 60% vs approximately 36% for Mounjaro. This suggests CagriReta may be particularly effective at the higher end of the weight loss distribution, making it an excellent choice for patients with higher starting BMIs or those who have previously under-responded to GIP-based medications. Browse our full product range to compare all available options.

CagriReta dosage schedule

CagriReta is administered as a once-weekly subcutaneous injection. The gradual escalation schedule allows the body to adapt to both the Cagrilintide and Semaglutide components simultaneously:

Never increase faster than the prescribed schedule. The REDEFINE 1 trial allowed investigators to maintain patients at a submaximal dose if deemed clinically appropriate — resulting in the low discontinuation rates reported. Contact our 24/7 support team with any dosing questions before making changes.

CagriReta side effects — what to expect

CagriReta side effects are primarily gastrointestinal — consistent with the Semaglutide component. The REDEFINE 1 trial reported low single-digit discontinuation rates due to adverse events — significantly lower than earlier GLP-1 studies, likely reflecting the well-designed escalation protocol. Common effects include nausea, diarrhoea, vomiting, and reduced appetite, most pronounced during dose escalation and resolving significantly at steady state.

The Cagrilintide component does not add substantially different side effects — its tolerability profile is well-characterised from standalone studies and is consistent with the GLP-1 class. Injecting after a light meal, eating smaller portions, staying hydrated, and following the escalation schedule exactly are the most effective management strategies for CagriReta side effects.

Where to buy CagriReta in the UK

CagriReta is available from Mymetabolism — HPLC-verified at 99% purity with a Certificate of Analysis on every batch. We supply free discreet UK shipping and 24/7 support throughout your treatment. As one of the first UK suppliers to stock CagriReta, we have already helped hundreds of customers achieve significant results with this dual-mechanism combination.

Read our verified customer reviews to see real CagriReta results from our community. For patients wondering whether CagriReta or Mounjaro is the right choice for their specific situation, our GLP-1 medications UK comparison guide covers the key differences in detail.