---
title: "Eloralintide vs Retatrutide: Amylin or Three Incretin Receptors"
canonical_url: https://peptidelibrary.app/blog/eloralintide-vs-retatrutide
description: "Eloralintide and retatrutide are both once-weekly investigational injections from Eli Lilly, but they act on different hormone systems. What each one targets, what their trials measured, and why no trial has compared them."
updated: 2026-11-08
publisher: Peptide Library
notice: "Research and educational use only. Not medical advice."
---

# Eloralintide vs Retatrutide: Amylin or Three Incretin Receptors

Eloralintide and retatrutide are both once-weekly investigational injections from Eli Lilly, but they act on different hormone systems. What each one targets, what their trials measured, and why no trial has compared them.

**Eloralintide and retatrutide are both investigational once-weekly injections from Eli Lilly for obesity, but they act on different hormone systems.** Eloralintide is a selective amylin receptor agonist. Retatrutide activates three receptors from the incretin and glucagon family: GIP, GLP-1 and glucagon. Neither is approved anywhere, and no trial has compared them.

They are less rivals than two separate bets on how to reduce food intake. Eloralintide copies a pancreatic hormone, amylin, that is released alongside insulin; retatrutide extends the GLP-1 approach that semaglutide and tirzepatide made familiar.

> **Both are investigational.** Neither eloralintide nor retatrutide is FDA-approved. Doses below are the amounts given in published trials, inside monitored protocols, and are reported for context only. Nothing here is dosing guidance.

## What each one is

- **Eloralintide** (LY3841136) is a long-acting amylin analogue. In cell assays it preferentially activated the human amylin 1 receptor, about 12-fold over the calcitonin receptor and 11-fold over the amylin 3 receptor, and its pharmacokinetics support once-weekly dosing (Briere 2025). Peptide Library has no profile for it yet; this article cites its trials directly.
- **Retatrutide** (LY3437943) is a single peptide that is an agonist at the GIP, GLP-1 and glucagon receptors, given once weekly (Jastreboff 2023). See the [retatrutide profile](https://peptidelibrary.app/library/retatrutide) or the [plain-language introduction](https://peptidelibrary.app/blog/what-is-retatrutide).

|  | **Eloralintide** | **Retatrutide** |
| --- | --- | --- |
| Hormone it mimics | Amylin | GIP, GLP-1 and glucagon |
| Receptors | Amylin receptors, preferring AMY1R | GIP, GLP-1 and glucagon receptors |
| Developer | Eli Lilly | Eli Lilly |
| Interval in trials | Once weekly, subcutaneous | Once weekly, subcutaneous |
| Stage | Phase 3 trials registered, none reported | Phase 3 trials reported in obesity and type 2 diabetes |
| Approved anywhere | No | No |

The closest approved relatives make the split clearer. [Pramlintide](https://peptidelibrary.app/library/pramlintide) is an older, short-acting amylin analogue; [tirzepatide](https://peptidelibrary.app/library/tirzepatide) is a GIP and GLP-1 agonist, and retatrutide adds glucagon to it. The [eloralintide vs cagrilintide comparison](https://peptidelibrary.app/blog/eloralintide-vs-cagrilintide) covers how eloralintide differs from the other long-acting amylin analogue.

## What the published trials measured

The two programmes are at different points and have studied different groups, so each is described on its own. We have deliberately not copied weight-loss percentages from the two programmes into this article: placed side by side, figures from trials with different populations, lengths and analysis methods invite exactly the cross-trial ranking the evidence cannot support. Each paper reports its own results against its own placebo group.

### Eloralintide

- **Repeated doses, phase 1.** 100 participants with obesity or overweight received once-weekly eloralintide or placebo for 12 weeks in five ascending-dose cohorts, without dose escalation. The most common adverse events were decreased appetite (19%), headache (12%) and fatigue (11%); diarrhoea (10%), nausea (8%) and vomiting (4%) were less frequent (Bhattachar 2026).
- Weight fell in a dose-dependent way compared with placebo. The most common adverse events were nausea and fatigue, with rates that varied by dose arm (Billings 2025).
- **Phase 3.** Lilly has registered several phase 3 trials, including NCT07321886 (about 1,980 adults with obesity or overweight without type 2 diabetes, four eloralintide doses against placebo, weight change at week 64). None has reported results.

### Retatrutide

- The most common adverse events were gastrointestinal, dose-related and partly reduced by a lower starting dose; heart rate rose in a dose-dependent way, peaking at 24 weeks (Jastreboff 2023).
- Body weight fell compared with placebo at every dose, and pain and sleep apnoea measures improved in the subgroups; gastrointestinal events were the most common adverse events (Jastreboff 2026).
- Diarrhoea and nausea were more common than with placebo, as were hypotension and dysaesthesia (Bellido 2026).

The [retatrutide dosage chart](https://peptidelibrary.app/blog/retatrutide-dosage-chart) sets out each arm against its source, and the [retatrutide side effects guide](https://peptidelibrary.app/blog/retatrutide-side-effects) covers the adverse-event reporting.

## Where they differ beyond the mechanism

- **Tolerability profile.** Retatrutide's adverse events are dominated by gastrointestinal effects, as with other GLP-1-based drugs. In eloralintide's trials, fatigue and decreased appetite feature alongside nausea, and gastrointestinal events were infrequent in the 12-week phase 1 study. Different trial designs make these rates impossible to line up directly.
- **Heart rate.** Retatrutide raised heart rate in a dose-dependent way in phase 2. A 2026 review of eloralintide's early studies reported reductions in pulse rate, in contrast with GLP-1 receptor agonists, while noting that the evidence comes from small, short phase 1 and 2 studies (Sigalov 2026).
- **How far along the evidence is.** Retatrutide has published phase 3 results in thousands of participants. Eloralintide's published human data come from fewer than 500 participants across three studies.
- **Combination plans.** Lilly is testing eloralintide with tirzepatide as a combination called EloraTZP, in a phase 3 trial that compares it with each drug alone and with placebo over 100 weeks (NCT07881432). We found no registered trial combining eloralintide with retatrutide (ClinicalTrials.gov search, November 2026).

## What the evidence does not show

- **Which one causes more weight loss.** No trial has randomised people to eloralintide versus retatrutide. Any percentage comparing them is arithmetic across separate trials with different populations, durations and analysis methods.
- **Long-term safety of eloralintide.** Its longest published trial lasted 48 weeks.
- **Cardiovascular outcomes.** Neither drug has reported a cardiovascular outcomes trial.

> **Research vials are not trial drug.** Material sold online under either name is not Lilly's investigational product, and none of the trial results above transfer to it.

## Frequently asked questions

### Is eloralintide a GLP-1 drug?

No. It is an amylin receptor agonist. Amylin is a different hormone, released by the pancreas alongside insulin.

### Is eloralintide stronger than retatrutide?

There is no way to say from the evidence. No trial has compared them, and their trials differ in population, length and design.

### Are eloralintide and retatrutide approved?

No. Both are investigational drugs in Lilly's clinical programme. Retatrutide has published phase 3 results; eloralintide's phase 3 trials are registered but have not reported.

### Can eloralintide and retatrutide be combined?

No published or registered trial has tested them together. Lilly's registered combination for eloralintide is with tirzepatide (EloraTZP).

> **Research and educational use only.** Peptide Library is an independent research and comparison platform and does not sell peptides. Nothing here is medical advice, dosing guidance, or a recommendation to administer any substance to a person or an animal. Consult a licensed clinician for anything concerning human health.

## Sources

- [Briere et al. Eloralintide (LY3841136), a novel amylin receptor agonist for the treatment of obesity: From discovery to clinical proof of concept. Mol Metab. 2025.](https://pubmed.ncbi.nlm.nih.gov/41109426/)
- [Bhattachar et al. Eloralintide, a selective, long-acting amylin receptor agonist for treatment of obesity: Phase 1 proof of concept. Diabetes Obes Metab. 2026.](https://pubmed.ncbi.nlm.nih.gov/41559929/)
- [Billings et al. Eloralintide, a selective amylin receptor agonist for the treatment of obesity: a 48-week phase 2, multicentre, double-blind, randomised, placebo-controlled trial. Lancet. 2025.](https://pubmed.ncbi.nlm.nih.gov/41207310/)
- [NCT07321886 — Phase 3 study of once-weekly eloralintide in adults with obesity or overweight without type 2 diabetes](https://clinicaltrials.gov/study/NCT07321886)
- [NCT07881432 — Phase 3 study of EloraTZP (eloralintide with tirzepatide) in adults with obesity without type 2 diabetes](https://clinicaltrials.gov/study/NCT07881432)
- [Sigalov et al. Cardiometabolic Risk Reduction Through Selective Amylin Receptor Agonism: Emerging Cardiovascular Implications of Eloralintide. Cardiol Rev. 2026.](https://pubmed.ncbi.nlm.nih.gov/42745233/)
- [Jastreboff et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. N Engl J Med. 2023.](https://pubmed.ncbi.nlm.nih.gov/37366315/)
- [Jastreboff et al. Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity (TRIUMPH-1). N Engl J Med. 2026.](https://pubmed.ncbi.nlm.nih.gov/42814954/)
- [Bellido et al. Retatrutide in adults with obesity and type 2 diabetes (TRIUMPH-2): a phase 3 trial. Lancet. 2026.](https://pubmed.ncbi.nlm.nih.gov/42810372/)
- [Bajaj et al. Efficacy and safety of retatrutide in people with type 2 diabetes and inadequate glycaemic control with diet and exercise (TRANSCEND-T2D-1): a phase 3 trial. Lancet. 2026.](https://pubmed.ncbi.nlm.nih.gov/42250575/)

Note: Dose figures are left out of this Markdown version. See the cited sources.