Survodutide and retatrutide are the two late-stage weight-loss drugs built around the same extra ingredient: glucagon receptor activity, added to GLP-1. That makes them the natural pair to compare — and the comparison people search for has never been run. This page lines up what each programme has reported, on the three things glucagon is supposed to change or might harm: weight, liver fat and the heart. Everything here is from published papers, company announcements and trial registrations as of 27 September 2026. Neither drug is approved.
Each drug against the approved benchmark is covered separately: survodutide vs tirzepatide and retatrutide vs tirzepatide. The retatrutide record in full, including what is being sold under its name, is on retatrutide.
The two molecules
| Survodutide | Retatrutide | |
|---|---|---|
| Maker | Boehringer Ingelheim (licensed from Zealand Pharma) | Eli Lilly |
| Receptors | glucagon + GLP-1 | GIP + GLP-1 + glucagon |
| Dosing in trials | weekly injection, 3.6 or 6.0 mg | weekly injection, 4, 9 or 12 mg |
| Phase 3 obesity result | SYNCHRONIZE-1, peer-reviewed (NEJM, Aug 2026) | TRIUMPH-1 to 4, company announcements |
| Filing | none announced | FDA filing planned Q1 2027 (Lilly) |
| Registered trials (ClinicalTrials.gov, 27 Sept 2026) | 26, of which 9 phase 3 | 33, of which 14 phase 3 |
Neither registry lists a trial that includes both drugs.
Weight — the gap is large, and the evidence is uneven
| Survodutide 6.0 mg (SYNCHRONIZE-1) | Retatrutide 12 mg (TRIUMPH-1) | |
|---|---|---|
| Length | 76 weeks | 80 weeks |
| People | 725 | 2,339 |
| Weight change | −13.0% | −28.3% (efficacy estimand); −25.0% counting everyone |
| Placebo | −5.4% | −2.2% (−3.9% counting everyone) |
| Status of the number | peer-reviewed | company release, awaiting publication |
On their own trials, retatrutide's average loss is roughly double. Two caveats keep that from being a measured difference. SYNCHRONIZE-1's placebo arm lost an unusually large 5.4%, which compresses survodutide's apparent effect (the reason is worked through on our survodutide page). And retatrutide's phase 3 numbers have not yet been through peer review. Survodutide also showed a flat dose response — 6.0 mg added 0.8 points over 3.6 mg — while retatrutide's trials show weight loss still rising at 12 mg.
Liver fat — the reason both contain glucagon
Glucagon acts directly on the liver, and both companies have tested their drug in metabolic dysfunction-associated steatotic liver disease (MASLD), the condition formerly called fatty liver disease, and its inflammatory form, MASH.
| Liver evidence | Survodutide | Retatrutide |
|---|---|---|
| Liver fat by MRI | SYNCHRONIZE-MASLD (phase 3, 216 people, 48 weeks): ≥30% reduction in 84.2% vs 24.3% on placebo (efficacy estimand; 68.5% vs 28.6% counting everyone) | Phase 2 substudy (98 people): −82.4% relative change at 12 mg by week 24, vs +0.3% on placebo; 86% reached normal liver fat (<5%) |
| Biopsy — steatohepatitis | Phase 2 (293 people, 48 weeks): improvement without fibrosis worsening in 47% / 62% / 43% at 2.4 / 4.8 / 6.0 mg vs 14% | none published |
| Biopsy — fibrosis | same trial: ≥1-stage improvement 34–36% vs 22% | none published |
| Phase 3 liver trials running | LIVERAGE (1,800 people, MASH, to Dec 2031); LIVERAGE-Cirrhosis (1,590, to June 2029) | multi-drug MASH master protocol (4,500 people, to Aug 2030) |
The difference that matters here is the kind of evidence, not the size of the numbers. Retatrutide's liver-fat drop is dramatic, but it is imaging in a small substudy. Survodutide has the only published biopsy data of the two — the measure regulators use to approve liver drugs — and its phase 2 result had an odd shape: the middle dose did best on steatohepatitis (62%), and the top dose (43%) did no better than the lowest. The authors fitted a curved dose response; the phase 3 biopsy trials, due from 2029, will show whether that holds.
The heart — the open question for both
Glucagon itself, at high doses, raises heart rate and blood pressure. A 2026 review in the Journal of the American Heart Association summarises the dual-agonist record so far: survodutide and mazdutide "generally" raised heart rate about as much as plain GLP-1 drugs, and lowered blood pressure — but at least one other glucagon dual agonist was discontinued, partly over "unacceptably large increases in heart rate" and QT prolongation. The authors conclude the effect has to be judged compound by compound, in outcome trials.
| Outcome trial | People | Primary completion | Results |
|---|---|---|---|
| Survodutide, SYNCHRONIZE-CVOT (NCT06077864) | 5,531 | 1 June 2026 (status: completed) | none posted on 27 Sept 2026 |
| Retatrutide, cardiovascular and kidney outcomes (NCT06383390) | 10,000 | February 2029 | trial ongoing |
Survodutide's is the first of the two due to report. Our retatrutide page lists what glucagon activity does to heart rate and liver measures over years as one of the things not yet known; the same is true of survodutide until its outcome trial is published.
What cannot be said yet
- Which works better — no head-to-head exists or is registered.
- Which is safer — both show mostly gastrointestinal side effects in trials (survodutide 80.9–89.7% at 3.6–6.0 mg in SYNCHRONIZE-1; retatrutide's most common at 12 mg were nausea 42.4% and diarrhoea 32.0% in TRIUMPH-1), but trial differences make the rates hard to compare, and neither has outcome data.
- Doses, prices, dates — no label, no price and no approval date exists for either. Per-compound dosing is not covered on this site.
This page reports trial records; it does not recommend either drug, and neither can be legally prescribed outside a trial. What is approved today is on which drugs are GLP-1s.
Sources
- Survodutide: SYNCHRONIZE-1, N Engl J Med 20 August 2026 (NCT06066515); SYNCHRONIZE-MASLD, Kaplan LM et al., Nat Med 2026;32:2948–2958, doi:10.1038/s41591-026-04479-3 (author correction 25 August 2026); phase 2 MASH trial, N Engl J Med 2024;391:311–319, doi:10.1056/NEJMoa2401755.
- Retatrutide: liver substudy, Sanyal AJ et al., Nat Med 2024;30:2037–2048, doi:10.1038/s41591-024-03018-2; TRIUMPH-1 results, Eli Lilly release, 21 May 2026.
- Cardiovascular effects of glucagon receptor signalling in multiagonists, J Am Heart Assoc 2026, doi:10.1161/JAHA.126.049727.
- ClinicalTrials.gov, intervention searches "survodutide" (26 records) and "retatrutide" (33 records), and records NCT06077864, NCT06383390, NCT06632444, NCT06632457, NCT07165028, 27 September 2026.