Eloralintide: What It Is, What the Trials Actually Show, and How It Compares to Retatrutide (October 2026)

A year ago almost nobody in the United States was searching for eloralintide. Over the past twelve months US search interest has risen roughly elevenfold. It peaked in the last days of September, when Eli Lilly took the stage at Europe's biggest diabetes meeting and showed that adding eloralintide to tirzepatide produced 23.3% average weight loss in people with type 2 diabetes. The fastest-rising question people are typing is "eloralintide vs retatrutide".

That's a fair question, because Lilly makes both and they work in completely different ways. Eloralintide copies amylin, not GLP-1. It is in five Phase 3 trials, it is nowhere near a pharmacy, and it is already for sale as a "research peptide". So what is it, what has actually been shown, and how does it stack up against the drugs it gets compared with? Let's dive in.

TLDR

What is eloralintide? An investigational once-weekly injectable from Eli Lilly (code LY3841136) that mimics amylin, a fullness hormone released by the pancreas alongside insulin. It is built to favour one amylin receptor subtype and largely leave the calcitonin receptor alone, which is what separates it from Novo Nordisk's cagrilintide.

Results: In the published Phase 2 trial, average weight loss at 48 weeks ranged from 9.5% on 1 mg to 20.1% on 9 mg, against 0.4% on placebo. Combined with tirzepatide as EloraTZP, up to 23.3% at 48 weeks in people with type 2 diabetes. That combination result is company topline and has not been published.

Dosage: Trials used 1 to 9 mg once weekly, some starting at the target dose and some stepping up from 3 mg. Phase 3 is testing four doses that Lilly hasn't disclosed. No validated protocol exists outside a trial.

Safety: Nausea and fatigue are the main side effects, both dose-related. Fatigue hit 43% to 46% on the 9 mg regimens against 12% on placebo. The longest human exposure on record is 48 weeks.

Legal Status (October 2026): Approved nowhere. In Phase 3 with primary completion dates in 2028. It cannot be lawfully compounded in the US, and any vial sold online is an unapproved drug from an unregulated source.

What Is Eloralintide, and Why Is It Trending Now?

Start with the hormone. Amylin is a 37-amino-acid peptide that your pancreatic beta cells release together with insulin every time you eat. It slows stomach emptying, blunts the glucagon spike after a meal, and tells the brainstem you have had enough (Hay et al., 2015, Pharmacological Reviews, PMID 26071095). It is one of the body's own "stop eating" signals, and it works through different neurons from GLP-1.

Eloralintide is Lilly's version of that signal. It is a single amylin analog with a fatty-acid chain attached so it binds albumin in the blood and circulates for a long time (Briere et al., 2025, Molecular Metabolism, PMID 41109426). How long is the surprising part: in the first human study, the half-life came out at 310 to 366 hours, roughly 13 to 15 days. That is about twice cagrilintide's.

The search graph has three reasons behind it.

The first is the Phase 2 result, published in The Lancet last November. Up to 20.1% average weight loss at 48 weeks from an amylin drug on its own, which no amylin-only drug had come close to before (Billings et al., 2025, The Lancet, PMID 41207310).

The second is the combination. On September 30, Lilly presented a Phase 2b trial of eloralintide plus tirzepatide, now branded EloraTZP, at the European Association for the Study of Diabetes meeting in Milan. The top combination beat tirzepatide 15 mg alone, 23.3% against 14.8%, and Lilly said it will start Phase 3 trials of a single-injection co-formulation before the end of 2026.

The third is retatrutide. The community that adopted Lilly's triple agonist over the past year spent September reading about amylin stacks, first cagrilintide (which we covered in our cagrilintide guide) and now this. Eloralintide is the amylin drug made by the same company as retatrutide, so the comparison writes itself.

Eloralintide is the amylin analog Lilly built to be different from cagrilintide on purpose: more selective, longer-lasting, and so far stronger on its own.

How Does Eloralintide Work?

Amylin receptors are strange. There is no single amylin receptor gene. The calcitonin receptor pairs with one of three helper proteins, called RAMPs, and each pairing makes a different amylin receptor subtype: AMY1, AMY2 and AMY3. The bare calcitonin receptor responds to amylin too (Hay et al., 2015).

Cagrilintide hits all of them, including the calcitonin receptor. Eloralintide was designed to be pickier. In human cell assays it activated the AMY1 receptor about 12 times more potently than the calcitonin receptor and about 11 times more potently than AMY3 (Briere et al., 2025). Lilly's bet is that the calcitonin receptor contributes to nausea without adding much weight loss, so avoiding it should buy tolerability.

The evidence for that bet is animal evidence. In lean rats, eloralintide caused significantly less conditioned taste avoidance than cagrilintide. That's a lab measure of nausea-like aversion: the rat learns to avoid a flavour paired with the drug (Briere et al., 2025). In obese rats it cut food intake and body weight, mostly as fat mass. One caveat from the same paper: at the rat receptors, eloralintide activated AMY3 strongly as well as AMY1, so the selectivity seen in human cells doesn't carry over neatly.

The selectivity is real in a dish. Whether it makes people feel better than cagrilintide does has never been tested, because the two have never been in the same trial.

Downstream, the effects look like amylin's: less hunger, earlier fullness, slower gastric emptying, and a modest effect on blood sugar. In people with type 2 diabetes, eloralintide alone lowered HbA1c by up to 1.4 points at 48 weeks, against 2.4 for tirzepatide 15 mg. Like cagrilintide, it is a weight drug first and a glucose drug second.

Eloralintide vs Retatrutide vs Cagrilintide vs Tirzepatide

Here is where eloralintide sits against the drugs it gets compared with. The figures come from separate trials with different populations and durations, so read across the rows with care. No trial has put eloralintide head-to-head with any of them except tirzepatide, in the EloraTZP study.

Sources: Billings et al., 2025; Lau et al., 2021, The Lancet, PMID 34798060; Garvey et al., 2025, NEJM, PMID 40544433; Jastreboff et al., 2022, NEJM, PMID 35658024; Jastreboff et al., 2023, NEJM, PMID 37366315; Lilly, September 30, 2026.

So, eloralintide vs retatrutide. Take the two Phase 2 trials, both 48 weeks long and both in people without diabetes. Retatrutide 12 mg gave 24.2%, eloralintide 9 mg gave 20.1%. Retatrutide is the stronger drug on paper, by about four points, and its Phase 3 numbers are higher again. Eloralintide's Phase 3 results won't exist until 2028.

The more interesting comparison is with cagrilintide. On its own, cagrilintide is a liraglutide-tier drug. Eloralintide's top doses landed in tirzepatide territory, without any incretin at all. A 2026 network meta-analysis of amylin-based drugs put high-dose eloralintide at 18.0 percentage points more weight loss than placebo, behind only high-dose amycretin and ahead of high-dose CagriSema (Kamrul-Hasan et al., 2026, Endocrinology, Diabetes & Metabolism, PMID 42175595). The authors call their own data "sparse" and "low-certainty", and they're right: the eloralintide input is one 263-person trial.

Here's the caveat that gets dropped: eloralintide's Phase 2 enrolled people with an average BMI of 39 and no diabetes, and 78% were women. People with type 2 diabetes lose less on every drug in this class. In the EloraTZP trial, which enrolled only people with diabetes, eloralintide alone managed 12.3% at its best dose, not 20%.

What the Evidence Actually Shows

Every human study of eloralintide was run and funded by Lilly. Here is what has passed peer review, separated from what exists only as a company announcement.

All weight figures above are Lilly's "efficacy estimand", the result had everyone stayed on treatment. The numbers that count everyone who was randomised, including people who stopped, are somewhat lower.

A few details in the Phase 2 data matter more than the headline.

The dose-response is real. Weight loss climbed steadily from 1 mg to 9 mg and hadn't clearly flattened at 48 weeks.

The way you get to the dose matters as much as the dose. According to the trial registration, the fixed-dose arms received their assigned dose from week one. The 6 mg group, which started at 6 mg, had nausea in 64% of participants. The group that stepped up from 3 mg to 6 mg to 9 mg over eight weeks had nausea in 25% and still lost 16.4%. Lilly's own summary says side effects were lower with slower escalation.

The arms were small, between 24 and 54 people each, so the dose-by-dose rates bounce around. That's why 9 mg straight shows less nausea than 6 mg straight.

Eloralintide has one published efficacy trial. It is a good trial, and it is one trial.

The combination trial adds a second point worth knowing. Eloralintide 6 mg plus the lowest tirzepatide maintenance dose, 5 mg, gave 19.4%, more than tirzepatide 15 mg alone. If that holds up in Phase 3, the pitch for EloraTZP is as much "the same result on less tirzepatide" as "a bigger result".

Lilly is also testing eloralintide with a second investigational molecule, macupatide, in two Phase 2 trials, and in ENLIGHTEN-6 as an add-on for people whose weight loss has stalled on a weekly incretin. That last trial is the closest anyone has come to studying the "add amylin to what you're already on" idea in humans. It includes no retatrutide arm.

Eloralintide Dosage: What the Trials Used vs What You'll See Online

Let's be clear about what exists. There are trial schedules, which are documented. There is gray-market practice, which isn't. Neither is a guideline, and nobody has published one.

What the trials used

Phase 2 tested 1, 3, 6 and 9 mg once weekly, plus two escalation schemes: 6 mg for 20 weeks then 9 mg, and 3 mg for four weeks, 6 mg for four weeks, then 9 mg. In the EloraTZP trial, everyone on eloralintide started at 1 mg or 3 mg and stepped up to 6 mg or 9 mg. The combination arms escalated every four weeks, with tirzepatide starting at 2.5 mg. Lilly says the Phase 3 co-formulation will use an "optimized escalation schedule" it hasn't described yet.

The half-life changes the arithmetic. At about two weeks, roughly 70% of each weekly dose is still in your system when the next one goes in. Blood levels keep climbing for around two months before they level off, which means a four-week escalation step is taken before the previous step has fully landed. It also means side effects that appear after a dose increase can take weeks to fade.

What the gray market sells

As of October 13, a price-tracking site listed eloralintide in stock from nine online vendors, with 10 mg vials priced from $85 to over $230, with a median of $160.20. Only one of the nine had a certificate of analysis verified with the issuing lab (PeptidePrices).

We could not find a community dosing protocol with any documented basis. The only schedules with data behind them are Lilly's. Nobody has published outcomes from gray-market use, at any size.

The dose matters for cost in a way it doesn't with most peptides. Trial doses are in milligrams, not micrograms. A 10 mg vial at 9 mg a week is barely one injection, so at those prices a trial-dose week costs roughly $77 to $144, before syringes and water.

The reconstitution arithmetic

For a 10 mg vial, units below are on a standard U-100 insulin syringe. Check them against the reconstitution calculator and the dosage calculator before drawing anything up.

At 6 and 9 mg the 2 mL mix won't fit in one U-100 syringe, which is why the 1 mL column exists. Whether the powder in a given vial dissolves cleanly at 10 mg/mL is something only the manufacturer knows, and gray-market vendors don't say.

No validated eloralintide protocol exists outside a clinical trial. The trial schedule is a fact about the trial, not an instruction.

Eloralintide Side Effects

Eloralintide's side effects are the amylin set, with one that stands out.

Fatigue. This is the signature one. In Phase 2, fatigue was reported by 0% on 1 mg, 13% on 3 mg, 29% on 6 mg, 43% on 9 mg and 46% on the 6-then-9 mg arm, against 12% on placebo (Billings et al., 2025). The slow 3-6-9 escalation brought it down to 21%. Lilly hasn't explained the cause, and it's unclear whether it is a property of the molecule, of amylin agonism generally, or of eating much less. If you've seen people asking whether retatrutide makes you tired, this is the drug where the answer is clearly yes at high doses.

Gastrointestinal. Nausea ran from 11% to 64% depending on dose and schedule, against 14% on placebo, and was similar to placebo at 1 mg and 3 mg. In the 12-week Phase 1 without escalation, GI effects were infrequent: diarrhea 10%, nausea 8%, vomiting 4% (Bhattachar et al., 2026, Diabetes, Obesity and Metabolism, PMID 41559929). Decreased appetite (19%) and headache (12%) were the other common reports there.

Combined with tirzepatide. GI side effects were more common on the combinations than on either drug alone, mostly during escalation. Discontinuation because of adverse events was 10.8% to 27.0% on EloraTZP, 0% to 10.8% on eloralintide alone and 2.9% on tirzepatide alone. Placebo was an odd 16.7%, which is one reason to wait for the full paper.

Hypoglycemia. No signal has been reported. Amylin lowers glucose in a meal-dependent way, which is why this hasn't been a problem in the class.

What's unknown. The longest human exposure is 48 weeks. There is no published data on stopping it, on weight regain afterwards, or on long-term use. The Phase 3 programme, with around 5,600 participants across the five ENLIGHTEN trials, is where those answers will come from. There is no human data at all on eloralintide combined with retatrutide.

The gray-market harm record

We found no published case reports of harm tied to gray-market eloralintide. That isn't the same as safety. It is new to the gray market, and nobody tracks outcomes. The nearest signal is from the same supply chain: an Australian health department recorded six cases of acute liver injury in people using products labelled as retatrutide, with a contaminant suspected. We covered that in our retatrutide guide.

The vial risk is the usual list: purity, endotoxin, sterility, and whether the stated milligrams are actually in there. That last one hits harder than usual here. At trial doses each vial is one injection, so a short-filled vial doesn't just weaken one dose out of ten, it is the dose.

Is Eloralintide Legal?

Eloralintide is not approved anywhere in the world. It is in Phase 3, and the five ENLIGHTEN trials have primary completion dates between January and June 2028. Lilly hasn't announced a filing date. On the trial timelines, an approval before 2029 would be fast.

Compounding is closed. Under section 503A, a pharmacy can only compound from a bulk ingredient that has a USP monograph, is a component of an FDA-approved drug, or is on FDA's 503A bulks list (FDA, bulk drug substances under section 503A). Eloralintide is none of those. FDA's statement on unapproved GLP-1 drugs names retatrutide and cagrilintide specifically, not eloralintide, but the same rule applies. Any telehealth clinic offering eloralintide today is offering something it cannot lawfully make.

The research-use-only label doesn't protect sellers either. In March, FDA sent warning letters to peptide vendors and treated dosing content and testimonials on their sites as proof the products were meant for people, whatever the disclaimer said (ArentFox Schiff, April 2026). And Lilly has shown it will sue: its August lawsuits targeted retatrutide sellers, including four research-use-only vendors. We found none that names eloralintide yet.

Enforcement targets the seller, not the buyer. But what arrives in the post is an unapproved drug from an unlicensed source, and every protection that comes with a pharmacy product is missing.

The Honest Take

Eloralintide is the most impressive amylin drug anyone has published. Twenty percent at 48 weeks on its own puts it in incretin territory, which nothing in its class had managed. The selectivity story is coherent, the half-life is unusual, and the Phase 3 programme is large.

It also has one efficacy trial. 263 people, mostly women, none with diabetes. The tolerability advantage over cagrilintide is a rat finding plus a story about receptors. The fatigue rate at the doses that produce the headline number is high enough that "favourable tolerability" depends a lot on how slowly you get there.

Against retatrutide, it isn't a rival. It's a different tool. Retatrutide is the stronger drug on every number we have. Eloralintide's case is that it gets most of the way there through a pathway that doesn't touch GLP-1 at all, and that it adds on top of tirzepatide. That second part is where Lilly is putting its money.

The gray-market vial is a different object from the trial drug. It's an unverified powder, at a dose that empties a vial a week, from vendors nobody tests. The moment that matters is 2028, when ENLIGHTEN reads out. Until then, the published data and the vial share a name and not much else.

FAQ

What is eloralintide?

An investigational once-weekly injectable from Eli Lilly that mimics amylin, a fullness hormone released with insulin after meals. It favours the AMY1 amylin receptor and largely spares the calcitonin receptor. It is in Phase 3 for obesity and is not approved anywhere.

Is eloralintide a GLP-1?

No. It doesn't act on the GLP-1 receptor at all. It works through amylin receptors, a separate appetite pathway, which is why Lilly is testing it both alone and on top of tirzepatide.

Eloralintide vs retatrutide: which is stronger?

Retatrutide, on current data. In separate 48-week Phase 2 trials, retatrutide 12 mg gave 24.2% weight loss and eloralintide 9 mg gave 20.1%. Retatrutide's Phase 3 toplines go higher still. They have never been compared directly, and they work on different receptors.

Eloralintide vs cagrilintide: what's the difference?

Both are once-weekly amylin analogs. Cagrilintide, from Novo Nordisk, also activates the calcitonin receptor; eloralintide was designed to mostly avoid it, and its half-life is roughly twice as long. On its own, eloralintide produced about 20% weight loss at 48 weeks, against about 11% for cagrilintide at 68 weeks.

What is EloraTZP?

Eloralintide combined with tirzepatide. In a 48-week Phase 2b trial in people with obesity and type 2 diabetes, the top combination gave 23.3% weight loss against 14.8% for tirzepatide 15 mg alone. Lilly plans to start Phase 3 trials of a single co-formulated injection by the end of 2026. The results are unpublished.

What is the eloralintide dosage?

Trials used 1 to 9 mg once weekly. The best-tolerated route to 9 mg was 3 mg for four weeks, then 6 mg for four weeks. There is no validated protocol outside a trial, and Phase 3 is testing four doses Lilly hasn't disclosed.

Does eloralintide make you tired?

Often, at high doses. Fatigue affected 43% of Phase 2 participants on 9 mg and 46% on the 6-then-9 mg schedule, against 12% on placebo. It was lower with slower escalation and absent on 1 mg.

What are the side effects of eloralintide?

Nausea, fatigue, decreased appetite, headache and other GI effects, all dose-related. Nausea ranged from 11% to 64% across Phase 2 arms against 14% on placebo, and was lowest on the low doses and the slowest escalation.

Can you stack eloralintide with retatrutide?

No human study has tested it. Lilly has paired eloralintide with tirzepatide and macupatide in trials, never with retatrutide. Both are unapproved, neither can be compounded, and the long half-lives mean any side effect would take weeks to clear.

When will eloralintide be FDA approved?

Not soon. The Phase 3 trials finish their primary data collection between January and June 2028, and Lilly hasn't announced a filing date. An approval before 2029 would be unusually fast.

Is eloralintide legal to buy?

It is not approved, cannot be compounded, and cannot be lawfully prescribed. Online vendors sell it as a research chemical, a label FDA has said does not protect sellers whose sites market to people. Enforcement targets sellers, but what you get is an unverified, unapproved drug.

Resources

Billings et al. (2025), The Lancet, eloralintide Phase 2 — https://pubmed.ncbi.nlm.nih.gov/41207310/

Briere et al. (2025), Molecular Metabolism, discovery, receptor selectivity and single-dose Phase 1 — https://pubmed.ncbi.nlm.nih.gov/41109426/

Bhattachar et al. (2026), Diabetes, Obesity and Metabolism, multiple-dose Phase 1 — https://pubmed.ncbi.nlm.nih.gov/41559929/

Kamrul-Hasan et al. (2026), Endocrinology, Diabetes & Metabolism, network meta-analysis of amylin-based therapies — https://pubmed.ncbi.nlm.nih.gov/42175595/

Hay et al. (2015), Pharmacological Reviews, amylin physiology and receptors — https://pubmed.ncbi.nlm.nih.gov/26071095/

Eli Lilly (November 6, 2025), eloralintide Phase 2 results and Phase 3 plans — https://lilly.gcs-web.com/news-releases/news-release-details/lillys-selective-amylin-agonist-eloralintide-demonstrated

Eli Lilly (September 30, 2026), EloraTZP Phase 2b results — https://investor.lilly.com/news-releases/news-release-details/lillys-eloratzp-combination-eloralintide-and-tirzepatide

CNBC (September 30, 2026), EloraTZP coverage — https://www.cnbc.com/2026/09/30/eli-lilly-obesity-drug-amylin-tirzepatide-weight-loss-trial.html

ClinicalTrials.gov, eloralintide Phase 2 arms (NCT06230523) — https://clinicaltrials.gov/study/NCT06230523

ClinicalTrials.gov, EloraTZP Phase 2b (NCT06603571) — https://clinicaltrials.gov/study/NCT06603571

ClinicalTrials.gov, ENLIGHTEN-1, obesity without diabetes (NCT07321886) — https://clinicaltrials.gov/study/NCT07321886

ClinicalTrials.gov, ENLIGHTEN-2, obesity with type 2 diabetes (NCT07282600) — https://clinicaltrials.gov/study/NCT07282600

ClinicalTrials.gov, ENLIGHTEN-3, obstructive sleep apnea (NCT07369011) — https://clinicaltrials.gov/study/NCT07369011

ClinicalTrials.gov, ENLIGHTEN-4, knee osteoarthritis pain (NCT07353931) — https://clinicaltrials.gov/study/NCT07353931

ClinicalTrials.gov, ENLIGHTEN-6, add-on to a weekly incretin (NCT07392190) — https://clinicaltrials.gov/study/NCT07392190

ClinicalTrials.gov, macupatide and eloralintide Phase 2 (NCT07589608) — https://clinicaltrials.gov/study/NCT07589608

Lau et al. (2021), The Lancet, cagrilintide Phase 2 — https://pubmed.ncbi.nlm.nih.gov/34798060/

Garvey et al. (2025), NEJM, REDEFINE 1 — https://pubmed.ncbi.nlm.nih.gov/40544433/

Jastreboff et al. (2022), NEJM, SURMOUNT-1 tirzepatide — https://pubmed.ncbi.nlm.nih.gov/35658024/

Jastreboff et al. (2023), NEJM, retatrutide Phase 2 — https://pubmed.ncbi.nlm.nih.gov/37366315/

BioPharma Dive (July 2026), retatrutide FDA filing moved to Q1 2027 — https://www.biopharmadive.com/news/lilly-retatrutide-fda-application-obesity-drug-results/825987/

PeptidePrices (checked October 13, 2026), eloralintide vendor listings — https://peptideprices.net/peptides/eloralintide

FDA, bulk drug substances used in compounding under section 503A — https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act

FDA, concerns with unapproved GLP-1 drugs, updated September 1, 2026 — https://www.fda.gov/drugs/drug-alerts-and-statements/fdas-concerns-unapproved-glp-1-drugs-used-weight-loss

ArentFox Schiff (April 2026), analysis of the March 31 research-use-only warning letters — https://www.afslaw.com/perspectives/alerts/ruo-ined-five-peptide-vendors-learn-research-use-only-not-legal-strategy