Not approved in the US
Retatrutide
What the label states
There is no labelled range, because there is no label. Retatrutide (LY3437943) is an investigational triple GIP, GLP-1 and glucagon receptor agonist with no marketing authorisation from the FDA or any other regulator, for any indication — so there is no approved starting dose, no maintenance dose, no escalation interval and no maximum to quote, and this page prints none of them. What can be reported is a trial. In the phase 2 obesity trial, participants were randomised to once-weekly subcutaneous retatrutide at maintenance doses of 1 mg, 4 mg, 8 mg or 12 mg, or placebo, for 48 weeks. Doses and outcomes from Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. N Engl J Med 2023;389(6):514–526 (PMID 37366315). Retatrutide is investigational and is not approved for use anywhere. That is a description of what was administered under supervision in a study; it is not a dose anyone outside the study has been told to take, and the arms must not be read as rungs of a ladder. The ten retatrutide entries on DailyMed are not a counter-example: all ten are filed by one registrant under the marketing category “Export only”, which registers product that may not lawfully be sold in the United States and whose content FDA does not review. One of those listings contains a four-step weekly titration that appears in no published trial. It is not reproduced here.
Quoted from the approved product label. Clinics commonly prescribe differently — more frequent, smaller injections of the same weekly total are routine — and where this site describes that, it is named as practice rather than as labelling.
- Route
- Subcutaneous, once weekly, in the published phase 2 trial. There is no approved route, because there is no approved product.
- Vehicle
- Not established. No regulator has approved a retatrutide product, so no vehicle, excipient list or concentration is specified anywhere that FDA has reviewed. Material in circulation is generally a lyophilised powder whose vehicle is created when the buyer adds bacteriostatic water.
- Usual barrel
- 100-unit insulin (1 mL)
- Strengths covered
- No strength page yet
Which syringe, and why
Begin with what is not being said: there is no labelled syringe for retatrutide, because there is no label. What follows is arithmetic about an instrument, not a recommendation about a drug. A 1 mL U-100 insulin barrel is the instrument compounded and grey-market peptides are drawn with, and it is graduated so 100 units make 1 mL — which is the whole of what can be stated with confidence here. The concentration is not a property of retatrutide but of whatever water volume was added to whatever mass of powder, so the same 25-unit mark can be several very different doses and no chart can tell you which without the numbers on your own vial. The 100-unit ceiling of the barrel is a property of the instrument, not a maximum dose. Nothing on this page states a dose to draw.
Administration
- 1
There is no approved administration procedure, and that is the first thing to know
Every other compound on this site has a labelled route, site, interval and technique because a regulator reviewed and approved one. Retatrutide has none of that. What follows describes what is known from a published trial and from the arithmetic of the instrument, and none of it constitutes instructions.
- 2
What the trial did
The phase 2 obesity trial gave retatrutide once weekly by subcutaneous injection over 48 weeks, to participants who were screened, randomised and followed under clinical supervision. That is the extent of what a published source supports about how this molecule has been given.
- 3
What this page will not tell you
A starting dose, a maintenance dose, an escalation schedule, an interval between steps, a reconstitution concentration or a beyond-use date. None of those exists for retatrutide in any source we can cite. Any page that supplies one has either invented it or copied it from an export-only listing that FDA did not review.
- 4
The arithmetic that is true regardless
A U-100 barrel is graduated so 100 units equal 1 mL. Dividing the milligrams in a vial by the millilitres of water added gives the concentration, and the dose divided by that concentration gives the volume. Those relationships hold whatever a regulator eventually decides, and getting them wrong is how a tenfold error happens.
- 5
Talk to a clinician about what is approved
Two triple- and dual-incretin classes already have FDA-approved products with labels, monitoring requirements and known adverse-effect profiles. If the reason you are on this page is weight, those are the conversations with something behind them.
Storage
- —No approved storage condition exists, because no approved product exists. Nothing on this page should be read as a storage instruction.
- —No beyond-use date is stated here. A beyond-use date is established by stability testing on a specific formulation in a specific container, and no such data has been published for retatrutide. Figures circulating in days — 28, 56 — are borrowed from other drugs.
- —The lyophilised-powder listings on DailyMed are export-only registrations whose content FDA does not review, so their storage statements are not a substitute for an approved one.
Monitoring
| Marker | When | Why |
|---|---|---|
| No monitoring schedule is published | Not established | Monitoring requirements come from a label, and there is no retatrutide label. The trial monitored participants under a protocol designed for a controlled study; that protocol is not a clinical monitoring plan for anyone outside it, and this page does not reconstruct one from it. |
| What the phase 2 trial reported | Over 48 weeks, under supervision | The trial’s published results are a record of what happened in 338 screened participants at 1, 4, 8 and 12 mg once weekly. They describe a studied population, not an expected outcome for a reader — and they are reported rather than recommended. |
Frequently asked questions
- What is the recommended dose of retatrutide?
- There is not one, and any page that gives you a figure has made it up. A recommended dose is something a regulator approves when it approves a label, and retatrutide has no label anywhere in the world, for any indication. What exists is a record of what was administered in a clinical trial: in the phase 2 obesity trial, once-weekly subcutaneous maintenance doses of 1 mg, 4 mg, 8 mg or 12 mg over 48 weeks, given under supervision to a screened and randomised population. That is a description of a study. It is not a starting dose, it is not a ladder, and the four numbers are not steps you climb between.
- Retatrutide is on DailyMed — doesn’t that mean it is FDA approved?
- No, and this is the single most important thing on this page. As of the September 2026 DailyMed publication there are ten retatrutide SPLs. All ten were filed by one registrant, Guangzhou Yixin Cross-border E-commerce Co., Ltd., and every one of them carries the marketing category “Export only” in its approval block. An export-only listing registers a product that may not lawfully be sold in the United States; FDA does not review or approve its content, and the registrant writes the text. The document type reads HUMAN PRESCRIPTION DRUG LABEL, which is exactly why it is mistaken for one. One of those listings contains a four-step weekly titration under the heading “Typical weekly dosing schedule (example shown — follow your prescriber)”. Those steps appear in no published trial. We do not reproduce them.
- How does retatrutide differ from semaglutide and tirzepatide?
- By how many receptors it engages, and by whether it is approved. Semaglutide is a GLP-1 receptor agonist; tirzepatide is a dual GIP and GLP-1 receptor agonist; retatrutide is described as a triple agonist at the GIP, GLP-1 and glucagon receptors. The first two have FDA-approved products with labels, indications, ceilings, monitoring requirements and adverse-effect data gathered across large approved programmes. Retatrutide has a phase 2 publication. The mechanistic difference is genuinely interesting; the regulatory difference is the one that matters if you are deciding what to take.
- How many units is a retatrutide dose on an insulin syringe?
- Unanswerable in the abstract, and the reason is worth understanding rather than working around. A U-100 barrel is graduated so 100 units make 1 mL, so the number of units is the dose divided by the concentration, times 100. But retatrutide has no approved concentration — material in circulation is a lyophilised powder, and the concentration is created the moment bacteriostatic water is added. The same 25-unit mark can be 1.25 mg or 3.75 mg depending on how much water went in. Our dosage chart and calculator will do that arithmetic against the figures on your own vial, and they deliberately stop there: they convert a dose, they do not suggest one.
- How long does a reconstituted retatrutide vial last?
- No figure is given here, and none should be given to you. How many whole doses a vial contains is arithmetic — vial mass divided by dose, rounded down — and the water volume makes no difference to it. How long the solution stays usable after water is added is a beyond-use date, and a beyond-use date comes from stability testing of a specific formulation in a specific container. No such data has been published for retatrutide. Anyone quoting you 28 days or 56 days is quoting a figure established for a different drug.
Sources
- [1]Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. N Engl J Med. 2023;389(6):514–526 (PMID 37366315)
- [2]DailyMed SPL search for retatrutide — ten listings, all Guangzhou Yixin Cross-border E-commerce Co., Ltd., all marketing category “Export only”. Verified against the DailyMed publication of 2026-09-18
- [3]DailyMed SPL — SALKALLI (RETATRUTIDE LYOPHILIZED POWDER 10MG), Guangzhou Yixin Cross-border E-commerce Co., Ltd., set id 4302eb14-2065-d22b-e063-6394a90a9dcf, SPL version 1, effective 2025-11-07. Marketing category “Export only”: not an FDA-approved label, and the listing whose titration this page declines to reproduce
Related
Educational reference, not medical advice. Dose, route and whether this compound is appropriate at all are decisions for your clinician.