These two produced almost the same weight loss — 20% for eloralintide, 20.9% for tirzepatide — through completely different receptors. Both belong to Eli Lilly. And Lilly is running trials that give them together rather than choosing between them. Which tells you how the company sees this, and it is not as a contest.
Side by side
| Eloralintide | Zepbound | |
|---|---|---|
| Status | Investigational, phase 3 | FDA approved |
| Target | Amylin receptor | GLP-1 and GIP |
| Weight loss | 20% at 48 wks (phase 2, n=263) | 20.9% at 72 wks (phase 3, n=2,539) |
| Nausea | 33% at 9 mg | 28% |
| Fatigue | 43–46% | 7% |
| Can you get it | No | Yes |
| Also approved for | — | Obstructive sleep apnoea |
| Maker | Eli Lilly — both | |
Why the comparison is the wrong question
Two drugs that hit the same receptor are alternatives: you take one or the other, and more of both is not more effect. Two drugs that hit different receptors are not alternatives. They can be added.
Zepbound works through GLP-1 and GIP. Eloralintide works through amylin, a separate hormone released by the pancreas alongside insulin. There is no overlap in target, and Lilly has registered trials studying eloralintide together with tirzepatide — a phase 1 and a phase 2 master protocol.
So the interesting number is not 20% against 20.9%. It is what happens when a drug that reaches 20% on its own is added to one that reaches 20.9% on its own. Nobody knows yet, and that is the question the programme is built around.
The same logic already exists in the market: CagriSema pairs an amylin analogue with semaglutide for precisely this reason — see CagriSema explained.
If you do compare them
The efficacy figures are close enough that the trial designs matter more than the difference. Eloralintide's 20% came from 263 people over 48 weeks in phase 2; tirzepatide's 20.9% from 2,539 over 72 weeks in phase 3. Phase 2 results routinely soften at scale, so the fair reading is that eloralintide has shown it can reach this territory, not that it has arrived there.
What is genuinely notable is the route. Reaching tirzepatide's figure without touching the GLP-1 receptor means the whole category's dependence on that one pathway is not necessary. That is a bigger finding than a percentage point either way.
Where eloralintide looks worse
One row, and it is a large gap.
Fatigue: 43 to 46% on eloralintide's top doses, against 7% for Zepbound. Roughly six times as much, and reported by nearly half the participants at the doses that produced the 20%.
It is not a footnote. Fatigue at that rate is the kind of thing that ends a course of treatment, and unlike eloralintide's nausea — which appears to depend on how gently you start — the fatigue tracked the final dose, so a slower climb does not obviously avoid it.
On nausea the two are closer than expected: 33% at eloralintide's 9 mg against Zepbound's 28%. But eloralintide's fixed 6 mg arm hit 64%, which shows how much the escalation matters. Full figures in eloralintide side effects.
What Zepbound has that decides it today
- Approval. A prescribable dose, a pharmacy, a manufacturer accountable for the vial, years of post-marketing data.
- Phase 3 evidence at scale — 2,539 participants against 263.
- A second indication, obstructive sleep apnoea, which can open insurance coverage that weight alone does not.
- Known long-term tolerability. Eloralintide's longest published exposure is 48 weeks in a phase 2.
Eloralintide cannot be prescribed at all. It is in phase 3 and recruiting, so a trial is the only legitimate route.
Which, and what to watch
- Treatment today: Zepbound, or another approved option — see the best GLP-1 for weight loss.
- Better molecule: too close to call, and the trials are not comparable.
- Better tolerated: Zepbound, decisively, on fatigue.
- The thing actually worth watching: the combination trials. Two mechanisms that add rather than compete is the direction this field is moving, and it is tracked in the GLP-1 pipeline tracker.
The other comparisons
Eloralintide vs Wegovy is the widest gap of the three, and eloralintide vs Ozempic is the one with no shared evidence.
Scientific References
3 sources- 1
Billings LK, Hsia S, Bays H, et al.
Eloralintide, a selective amylin receptor agonist for the treatment of obesity: a 48-week phase 2 randomised trial
The Lancet · 406(10520) · 2025PMID: 41207310
- 2
Jastreboff AM, Aronne LJ, Ahmad NN, et al.
Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1)
New England Journal of Medicine · 387(3) · 2022PMID: 35658024
NEJM - 3
U.S. National Library of Medicine
ClinicalTrials.gov — NCT06916065 and NCT06143956, eloralintide studied alone and in combination with tirzepatide; read 13 August 2026
ClinicalTrials.gov · 2026
References open in a new tab. Content is reviewed against peer-reviewed literature as part of our editorial policy.
About the author
Editor, Modern Weight Science
Claudiu Gheorghe is the editor of Modern Weight Science. He is not a physician. His role is to synthesize peer-reviewed studies, clinical-trial data, and FDA prescribing information into clear, plain-language explanations, and to make sure every factual claim on the site traces back to a cited source. Any decision about starting, changing, or stopping a medication belongs with a licensed clinician who knows your history.
Every claim is checked against peer-reviewed research through our review process and fact-checking policy.
Frequently Asked Questions
Is eloralintide better than Zepbound?
Too close to call, and the trials are not comparable. Eloralintide reached 20% mean weight loss over 48 weeks in a 263-person phase 2; tirzepatide reached 20.9% over 72 weeks in a 2,539-person phase 3. Phase 2 figures often soften at scale. What is notable is that eloralintide got there without using the GLP-1 receptor at all.
Can eloralintide and Zepbound be taken together?
That is exactly what is being tested. They target different receptors — amylin against GLP-1 and GIP — so they can add rather than compete, and Eli Lilly, which owns both, has registered trials studying eloralintide with tirzepatide. No combination results have been published. The same logic underlies CagriSema, which pairs an amylin analogue with semaglutide.
Which has worse side effects, eloralintide or Zepbound?
Eloralintide, on fatigue, and the gap is large: 43 to 46% at its top doses against Zepbound's 7%. On nausea they are closer, 33% against 28%, though eloralintide's fixed 6 mg arm reached 64% — the escalation appears to matter more than the dose. These are separate trials with different reporting, so read the direction.
Are eloralintide and Zepbound made by the same company?
Yes, both are Eli Lilly. Zepbound is tirzepatide, approved, acting on GLP-1 and GIP. Eloralintide is investigational and acts on the amylin receptor. Lilly is running trials of the two together, which says more about how it sees them than any comparison does.
Should I wait for eloralintide instead of taking Zepbound?
It is in phase 3 with no approval date, so waiting means waiting years with no result in the meantime. Zepbound is available now, has phase 3 evidence in 2,539 people, and carries a second indication for obstructive sleep apnoea. The more likely future is not choosing between them but taking both, and that is still in trials.
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Where to read next
Not medical advice. This guide is for general education only. GLP-1 medications, dosing, and treatment suitability are decisions for you and a licensed clinician who knows your full medical history.