Retatrutide vs Cagrilintide
Comprehensive side-by-side comparison of mechanisms, dosing, side effects, and research
Also: LY3437943, Triple G
Retatrutide is the heavy hitter of the new weight-loss drugs: a once-weekly injectable peptide that hits three receptors at once - GIP, GLP-1, and glucagon - earning it the nickname triple-G agonist. In a phase 2 trial it produced some of the largest weight loss ever recorded for a drug, up to roughly 24 percent of body weight at the top dose. It is investigational, made by Eli Lilly, and not yet FDA approved as of 2026.
Also: AM833, NN9838
Cagrilintide (also called AM833) is a long-acting synthetic analog of amylin, the gut-brain satiety hormone co-secreted with insulin by pancreatic beta cells. It is an investigational once-weekly injectable being developed by Novo Nordisk for obesity, most prominently as the amylin half of CagriSema (cagrilintide plus semaglutide). It is not yet approved as a standalone drug, but it has cleared phase 2 trials and is in late-stage development.
Key Comparison Insights
- Both peptides belong to the Weight Loss category, suggesting similar primary applications.
Detailed Comparison
| Attribute | Retatrutide | Cagrilintide |
|---|---|---|
| Category | Weight Loss | Weight Loss |
| FDA Status | Not FDA Approved | Not FDA Approved |
| Clinical Status | Pre I II III IV FDA | Pre I II III IV FDA |
| Mechanism of Action | Retatrutide combines three hormone signals into one molecule. The GLP-1 component curbs appetite and slows stomach emptying, the GIP component supports insulin response and may improve how fat tissue handles nutrients, and the added glucagon receptor activity is the novel piece: glucagon can increase energy expenditure and fat burning in the liver. The idea is that two arms cut how much you eat while the third raises how much you burn, which is why retatrutide is thought to push weight loss further than GLP-1-only drugs like semaglutide or even the dual GIP/GLP-1 agonist tirzepatide. The exact contribution of each receptor in humans is still being worked out, so consider the glucagon-driven energy-expenditure story a strong hypothesis rather than fully nailed down. | Cagrilintide is a non-selective agonist of the amylin and calcitonin receptor family. It activates amylin receptors (which are calcitonin receptors paired with RAMP accessory proteins) to signal satiety in the brain, slow gastric emptying, and blunt the post-meal glucagon rise. Mechanistic work in mice shows it reduces body weight mainly through amylin receptors AMY1R and AMY3R acting in the hindbrain, with the area postrema as a key entry point and downstream signaling through the nucleus of the solitary tract and parabrachial nucleus. Notably, weight loss in those studies persisted even after the acute appetite-suppressing effect faded, hinting at effects on energy balance beyond simple food-intake reduction. Chemically it is built on a pramlintide-like 37-amino-acid backbone with substitutions and a fatty-diacid chain attached to extend its half-life to roughly a week, enabling once-weekly dosing. |
| Common Dosing | 4-12 mg weekly Once weekly, same day each week | 2.4 mg weekly Once weekly |
| Administration | Subcutaneous injection weekly | Subcutaneous injection once weekly |
| Typical Duration | Long-term use expected | Long-term / chronic use expected |
| Best Time to Take | Morning, same day each week | Any consistent time weekly |
Possible Side Effects May vary by individual |
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| Research Summary | The key human evidence is the phase 2 trial by Jastreboff and colleagues, published in the New England Journal of Medicine in 2023, which randomized 338 adults with obesity (without type 2 diabetes) over 48 weeks. Mean weight reduction reached about 24 percent at the 12 mg dose, and weight loss had not clearly plateaued by week 48, hinting the ceiling could be even higher. Among participants with prediabetes at baseline, a large majority returned to normal blood sugar. Side effects were dominated by gastrointestinal issues like nausea, vomiting, and diarrhea, the familiar pattern for this drug class, and were mostly dose-dependent. These are genuinely strong phase 2 results, but they are phase 2: larger and longer phase 3 trials are underway to confirm safety and durability, and retatrutide sold outside of trials is not an approved, quality-controlled medicine. | Cagrilintide has real human data, which sets it apart from most peptides in this category. In a 2021 Lancet phase 2 dose-finding trial (Lau et al.), once-weekly cagrilintide at 4.5 mg produced about 10.8% mean body weight loss over 26 weeks, beating both placebo (around 3%) and liraglutide 3.0 mg (around 9%), establishing that amylin agonism alone can drive clinically meaningful weight loss. Its bigger story is combination therapy: paired with semaglutide as CagriSema, it advanced into phase 3 REDEFINE trials for obesity and type 2 diabetes, with reported weight loss in the low 20% range, though final results came in somewhat below the most optimistic expectations. Side effects are dominated by the expected gastrointestinal effects (nausea, vomiting) common to gut-hormone drugs. As of 2026 cagrilintide is investigational and not FDA-approved on its own. The evidence is genuinely human and well-controlled here, which is rare, but it is still a drug under regulatory review rather than an approved therapy. |
Frequently Asked Questions: Retatrutide vs Cagrilintide
What is the difference between Retatrutide and Cagrilintide?
Retatrutide is a weight loss peptide that retatrutide is the heavy hitter of the new weight-loss drugs: a once-weekly injectable peptide that hits three receptors at once - gip, glp-1, and glucagon - earning it the nickname triple-g agonist. in a phase 2 trial it produced some of the largest weight loss ever recorded for a drug, up to roughly 24 percent of body weight at the top dose. it is investigational, made by eli lilly, and not yet fda approved as of 2026. Cagrilintide is a weight loss peptide that cagrilintide (also called am833) is a long-acting synthetic analog of amylin, the gut-brain satiety hormone co-secreted with insulin by pancreatic beta cells. it is an investigational once-weekly injectable being developed by novo nordisk for obesity, most prominently as the amylin half of cagrisema (cagrilintide plus semaglutide). it is not yet approved as a standalone drug, but it has cleared phase 2 trials and is in late-stage development. The main differences lie in their mechanisms of action and clinical applications.
Which is better, Retatrutide or Cagrilintide?
Neither is universally "better" - the choice depends on your specific goals. Retatrutide is typically used for weight loss purposes, while Cagrilintide is used for weight loss. Always consult with a healthcare provider to determine which may be appropriate for your situation.
Can Retatrutide and Cagrilintide be used together?
Some peptide protocols combine multiple compounds for synergistic effects. However, using Retatrutide and Cagrilintide together should only be considered under medical supervision, as both compounds have their own side effect profiles and potential interactions. Research on their combined use may be limited.