Retatrutide vs Cagrilintide: 28.7% vs 11.8% (2026 Comparison)

On paper, this looks like a blowout. Retatrutide produced 28.3–28.7% average weight loss in its Phase 3 trials. Cagrilintide, tested alone, produced 11.5–11.8%. That's less than half.

But comparing them purely on that number misses what's actually going on. Retatrutide is a triple hormone agonist — it activates GLP-1, GIP, and glucagon receptors, the same appetite-and-metabolism pathway that every major weight loss drug of the last five years has built on. Cagrilintide doesn't touch that pathway at all. It's a long-acting amylin analog — a completely different hormone system, acting on different parts of the brain, tested here as a standalone treatment rather than as part of a combination.

That distinction matters more than the raw numbers suggest. Cagrilintide was never designed to be used alone in Novo Nordisk's long-term plans — it's the amylin half of CagriSema, the cagrilintide-plus-semaglutide combination that reached 20.4–22.7% in the same trial that tested cagrilintide by itself. But the monotherapy data exists, it's real, and it points to something specific: a mechanism that may work for patients whose problem with GLP-1 drugs isn't lack of interest — it's that their stomachs can't tolerate them.

This article compares what each drug actually does, what the trial data shows, and — more usefully than "which number is bigger" — who each one might actually be right for.

Quick Comparison

What Is Cagrilintide, Actually?

Cagrilintide is a long-acting analog of amylin — a hormone your pancreas releases alongside insulin after you eat. Native amylin signals fullness, slows how fast your stomach empties, and helps regulate blood sugar by suppressing glucagon release right after meals. The problem with using amylin itself as a drug is that it disappears from the bloodstream in minutes. Cagrilintide solves that with a fatty-acid modification that stretches its half-life to roughly 7–8 days, making once-weekly dosing possible — the same engineering trick used to turn native GLP-1 into semaglutide and tirzepatide.

The important part: amylin and GLP-1 are different signaling systems. GLP-1 drugs (semaglutide, tirzepatide, and the GLP-1 component of retatrutide) act primarily through receptors in the hypothalamus. Amylin acts through a different region — the area postrema, in the brainstem. This is why amylin-based and GLP-1-based appetite suppression are described as complementary rather than redundant, and it's the entire rationale behind combining the two as CagriSema.

Cagrilintide has never been studied as a long-term standalone therapy at Phase 3 scale outside of its role as one arm in a combination trial. That changes the interpretation of the monotherapy number below — it's real data, but it comes from a trial that wasn't designed to optimize cagrilintide alone.

Clinical Trial Results

Retatrutide: TRIUMPH Program

Retatrutide has completed all four of its core Phase 3 trials as of August 2026. The two relevant to this comparison — TRIUMPH-4 and TRIUMPH-1, both in non-diabetic obesity populations — produced consistent results:

For the full breakdown of all four TRIUMPH trials, including TRIUMPH-2 and TRIUMPH-3 in more complex populations, see our complete clinical results guide.

Cagrilintide: REDEFINE-1 Monotherapy Arm

Cagrilintide's efficacy data comes from REDEFINE-1, the same Phase 3 trial that established CagriSema. REDEFINE-1 randomized 3,417 adults with obesity or overweight (plus at least one weight-related comorbidity, no diabetes) in a 21:3:3:7 ratio to CagriSema, semaglutide alone, cagrilintide alone, or placebo — all at 2.4mg, over 68 weeks. The cagrilintide-alone arm included 302 participants.

Efficacy (trial product) estimand assumes full treatment adherence; treatment policy estimand reflects real-world adherence patterns. Both are pre-specified statistical approaches, not different populations.

Roughly 1 in 3 participants (31.6%) on cagrilintide monotherapy achieved ≥15% weight loss, compared to about 1 in 20 (4.7%) on placebo. That's a real, statistically significant effect from a single-mechanism amylin drug — it's just a smaller effect than what triple-receptor activation or GLP-1 agonism alone typically produces.

Why the Efficacy Gap Exists

Three factors explain most of the difference:

Number of pathways activated. Retatrutide hits three receptor systems simultaneously — appetite suppression through GLP-1, improved insulin sensitivity and tolerability through GIP, and increased energy expenditure through glucagon. Cagrilintide activates one: the amylin/calcitonin receptor system. More mechanisms generally means more weight loss, which is exactly the same logic behind tirzepatide (two mechanisms, ~22.5%) outperforming semaglutide (one mechanism, ~14.9%).

Amylin alone is a moderate suppressant, not a powerful one. Amylin's primary jobs — slowing gastric emptying and increasing satiety per meal — produce real but modest calorie reduction on their own. It's most powerful as an addition to GLP-1 agonism, not as a replacement for it. That's precisely what the CagriSema data shows: cagrilintide roughly doubles semaglutide's effect when added to it, but doesn't come close to matching semaglutide's effect by itself.

It was never optimized to be used alone. REDEFINE-1 was designed to prove CagriSema works, with the cagrilintide-only and semaglutide-only arms included as scientific comparators — not as a dedicated attempt to push cagrilintide monotherapy to its ceiling. A dedicated cagrilintide-only program (Novo Nordisk's planned RENEW trials) could plausibly find higher numbers with different dosing or titration strategies, but that data doesn't exist yet.

Side Effects: A Genuinely Different Profile

Retatrutide

Retatrutide's side effect profile is well-characterized across its Phase 3 program: nausea in roughly 42–43% of patients at 12mg, diarrhea around 32–33%, vomiting 20–25%, and dysesthesia (abnormal skin sensations) unique to retatrutide at 12.5–20.9% depending on trial population. Discontinuation due to adverse events ranges 11.3–18.2% depending on population. For the complete breakdown, see our retatrutide side effects guide.

Cagrilintide

Cagrilintide's adverse events are also predominantly gastrointestinal — nausea, vomiting, diarrhea, constipation — occurring mainly during dose escalation and described in the primary REDEFINE-1 publication and at the ADA 85th Scientific Sessions as mainly transient and mild-to-moderate. What's notably absent from cagrilintide's profile: dysesthesia has not been reported as a signal for amylin-based therapy the way it has for retatrutide.

The specific arm-level GI percentage for cagrilintide monotherapy hasn't been published with the same granularity as retatrutide's — REDEFINE-1's public reporting emphasizes the CagriSema-vs-placebo comparison (79.6% vs 39.9% experiencing any GI event) more than the smaller 302-person monotherapy arm specifically. What is publicly documented is a genuine, ongoing scientific interest in whether cagrilintide's different mechanism translates to better tolerability for a specific group: patients who couldn't tolerate GLP-1 drugs in the first place. Novo Nordisk has a dedicated trial — not yet recruiting as of mid-2026 — specifically evaluating cagrilintide's tolerability in people who discontinued GLP-1 receptor agonist therapy due to gastrointestinal side effects (NCT07607587). That trial existing at all is a meaningful signal about where cagrilintide's real clinical niche may lie — not as a stronger option, but as an alternative pathway for people the strongest options don't work for.

Regulatory Status: Neither Is Approved, But They're Not on the Same Track

Retatrutide has completed all four of its core registrational trials as of August 2026. Eli Lilly is expected to submit a Biologics License Application (BLA) — not an NDA, since retatrutide is a biologic — in Q1 2027, with FDA approval projected between Q3 2027 (priority review) and Q1–Q2 2028 (standard review). Realistic launch: late 2027 to mid-2028. For the full regulatory timeline, see our FDA approval timeline guide.

Cagrilintide as a standalone drug has no filing timeline at all. Novo Nordisk has not submitted, and has not announced plans to submit, an application for cagrilintide monotherapy on its own. The only path to market for this molecule that currently has a regulatory filing in motion is CagriSema — the combination — which Novo Nordisk submitted to the FDA on December 18, 2025, with a decision expected in 2026. A dedicated Phase 3 program for cagrilintide alone (RENEW) was announced in September 2025 with a planned Q4 2025 start; results from that program, if it proceeds, would come years before any standalone regulatory filing could follow.

Practically: if you're interested in cagrilintide's mechanism specifically, CagriSema — not standalone cagrilintide — is the version on a real path to your pharmacy. For the full picture on that combination, see our retatrutide vs CagriSema comparison.

Who Each One Might Actually Fit

This isn't really a "which is more effective" decision — the efficacy gap is too large for that framing to be useful. It's a "different tool for a different problem" decision.

Retatrutide is built for maximum pharmacological weight loss. If you have severe obesity, multiple weight-related complications, or have already tried GLP-1-based options and need meaningfully more, retatrutide's triple-receptor mechanism is designed to deliver the highest ceiling currently in development.

Cagrilintide's real relevance is for people GLP-1 drugs don't work for — because their body won't tolerate them, not because they're not interested. If nausea, vomiting, or GI intolerance forced you to stop semaglutide or tirzepatide, a completely different mechanism — one that doesn't touch the GLP-1 pathway at all — may be worth watching, even at a more modest efficacy ceiling. That's a real, currently-being-studied use case, not a hypothetical one.

Neither is available today. For patients who need treatment now, tirzepatide (Zepbound, 22.5% average weight loss) and semaglutide (Wegovy, 14.9%) remain the only FDA-approved options in this class. For a complete look at what's approved now versus what's coming, see our complete retatrutide guide.

Conclusion

Retatrutide beats cagrilintide monotherapy by a wide margin on weight loss — 28.3–28.7% versus 11.5–11.8% — but that comparison, taken alone, misunderstands what each drug is for. Retatrutide is a triple-mechanism drug built to maximize weight loss. Cagrilintide is a single-mechanism amylin drug that was never intended to be used alone in Novo Nordisk's actual development plan — its real destination is CagriSema, where it roughly doubles semaglutide's effect.

The genuinely interesting question isn't which number is bigger. It's whether cagrilintide's fundamentally different mechanism — acting on amylin pathways rather than GLP-1 — turns out to help the specific population that current GLP-1 drugs fail: people who can't tolerate them, not people who need more from them. Novo Nordisk is actively studying exactly that question. Until that data exists, and until either drug is actually approved, this remains a comparison of two different clinical futures rather than two competing products.

Sources

• Garvey WT, et al. "CagriSema for the Treatment of Overweight or Obesity." New England Journal of Medicine, 2025. (REDEFINE-1)
• Novo Nordisk press release: CagriSema 2.4mg/2.4mg demonstrated 22.7% mean weight reduction in REDEFINE 1, published in NEJM. June 22, 2025.
• Novo Nordisk / BioSpace: Novo Nordisk presents phase 3 data for next-generation amylin cagrilintide, leading to advancement into dedicated clinical programme. September 16, 2025.
• Novo Nordisk press release: Novo Nordisk files for FDA approval of CagriSema. December 18, 2025.
• ADA Meeting News: REDEFINE trials advance combination treatment for weight management. June 23, 2025.
• ClinicalTrials.gov: NCT07607587 — Evaluation of the Tolerability of Cagrilintide in Participants Not Tolerating GLP-1-RA Therapies Due to Gastrointestinal Adverse Events.
• Eli Lilly press release: TRIUMPH-4 Phase 3 topline results. December 11, 2025.
• Eli Lilly press release: TRIUMPH-1 Phase 3 topline results. May 21, 2026.