Retatrutide dosage chart: what trials actually used, mg by mg

Last updated 2026-07-25

What is the real retatrutide dosage chart, based on actual trial data?

There's only one dosage chart worth trusting right now, and it comes from the phase 2 obesity trial registered on ClinicalTrials.gov as NCT04881760, formally titled "A Study of LY3437943 in Participants Who Have Obesity or Are Overweight." LY3437943 is the development code for retatrutide ^[1]. Everything else floating around online, the vendor PDFs, the forum spreadsheets, the Reddit dosing guides, is either extrapolated from this one trial or made up entirely. The trial tested weekly subcutaneous injections across a titration scheme, landing on maintenance doses of 1mg, 4mg, 8mg, and 12mg, compared against placebo ^[2]. Results were published in the New England Journal of Medicine in 2023 (Jastreboff et al.), and the headline number is a mean 24.2% weight reduction at the 12mg dose at 48 weeks, against 2.1% for placebo ^[2]. Here's the important caveat before anyone reads further: this is a chart of what researchers gave trial participants under close medical monitoring, with lab work, titration schedules, and dropout management built into the protocol. It is not a chart of what anyone should inject at home. No clinician can lawfully prescribe retatrutide outside a registered trial right now, a point we'll come back to more than once in this piece because it matters more than the numbers do. | Dose (weekly, SC) | Trial arm | Reported outcome at 48 weeks |

How much bac water do you need for 10mg retatrutide?

This is one of the most searched questions about retatrutide, and the honest answer is: there's no sanctioned reconstitution instruction for retatrutide at any strength, because there's no approved retatrutide product and no compounding pathway that would generate an official prep sheet. Anything you find online, including specific bacteriostatic water volumes for a 10mg vial, comes from vendor marketing or peer-to-peer guesswork, not from a lab-verified protocol. What trial reconstitution methods look like is not public in fine detail either. The NEJM publication reports dosing amounts and outcomes, not vial-by-vial reconstitution steps, because study drug in a clinical trial is prepared by trained research pharmacy staff following a sponsor-controlled protocol, not a home kit ^[2]. The deeper problem: even if you found a mathematically "correct" dilution ratio, that math doesn't fix the legal and quality problem underneath it. A concentration calculation can't tell you whether the powder in the vial is actually retatrutide, whether it's sterile, or whether it's dosed accurately at all. Material sold outside FDA oversight has none of the manufacturing controls that 503A compounding law requires, including registration under FD&C Act section 510 and a valid certificate of analysis for the bulk substance ^[3]. A reconstitution chart is meaningless if you can't verify what's actually in the vial. If you're trying to understand reconstitution math in the abstract, a retatrutide dosage calculator walks through the concentration arithmetic, and a separate guide on how to reconstitute retatrutide covers the mechanics people ask about most, alongside the legal reality that should factor into any decision here.

How long will 10mg of retatrutide last once mixed?

There's no reviewed stability data answering this for retatrutide specifically, because there's no approved retatrutide product with a published stability profile, storage temperature range, or beyond-use date backed by regulatory review. Anything you see quoting a specific number of days or weeks for a reconstituted vial is not sourced from an FDA label or a peer-reviewed stability study, and you should treat those numbers as unverified. For context, approved peptide-class injectables like semaglutide (OZEMPIC, WEGOVY) and tirzepatide (MOUNJARO, ZEPBOUND) carry FDA-reviewed storage and in-use stability instructions on their labels ^[4]. That kind of data comes from formal stability studies submitted as part of an approved New Drug Application. Retatrutide has never gone through that process. A Drugs@FDA search for the generic name retatrutide returns no approved product at all ^[4]. So the honest answer to "how long will 10mg last" is: nobody outside the trial sponsor has data you should trust, and material from unregistered suppliers gives you no certificate of analysis to even confirm starting purity, let alone how it degrades over time ^[3]. This isn't a gap that a forum consensus can fill.

What does a retatrutide 30mg vial reconstitution actually involve?

Vials sold as "30mg retatrutide" are common in gray-market listings, and the marketing usually implies a straightforward reconstitution ratio like any peptide product. But the more relevant question isn't the arithmetic, it's whether that vial is retatrutide at all, at the labeled amount, made under conditions anyone can verify. Under federal law, a bulk drug substance used in compounding has to come through one of three pathways: compliance with an applicable USP or NF monograph, status as a component of an FDA-approved drug, or inclusion on the 503A Bulks List when neither of the first two applies ^[3]. Retatrutide fails all three tests. There is no USP or NF monograph for it. It is not a component of any approved drug, since none exists ^[4]. And it does not appear on the 503A Bulks List, which contains exactly six substances: Brilliant Blue G, cantharidin, diphenylcyclopropenone, N-acetyl-D-glucosamine, squaric acid dibutyl ester, and thymol iodide ^[5]. No peptide is on that list, retatrutide included. On top of the ingredient cascade, 503A separately requires the bulk substance to be manufactured by an establishment registered under FD&C Act section 510 and accompanied by a valid certificate of analysis ^[3]. Research-use-only material from an unregistered supplier fails this requirement regardless of what the ingredient cascade says. A "30mg vial" from a gray-market seller checks none of these boxes, which means the reconstitution question is close to beside the point. You'd be doing careful math on an unverifiable product.

Is there a real retatrutide 20mg or 10mg dose being studied?

The phase 2 trial's highest studied dose was 12mg weekly, not 20mg ^[2]. If you're seeing "20mg" or "30mg" retatrutide products marketed anywhere, that's a vendor label, not a studied clinical dose from the published trial record. Retatrutide has moved into later-phase trials as well, registered as NCT05929066 and NCT05882045, and those records list enrollment criteria, comparators, and dosing endpoints under study ^{[6] [7]}, but the publicly reported efficacy numbers everyone cites (the 24.2% figure) come from the 12mg arm of the original phase 2 study ^[2]. A 10mg dose isn't one of the four maintenance arms reported in the NEJM paper either (1mg, 4mg, 8mg, 12mg) ^[2]. If a product is marketed at exactly 10mg, that's a packaging choice by whoever made it, not a replicate of a trial arm. Worth remembering: retatrutide has also been studied in registered type 2 diabetes trials beyond the obesity program, so the evidence base isn't limited to weight loss alone ^[6], but no dose from any of these trials has moved into an approved product with a labeled dosing schedule.

Why can't a US pharmacy legally compound or dispense retatrutide?

This is the question that actually matters more than any specific milligram number, and the answer is layered but clear once you walk through it. First, retatrutide has no FDA approval for any indication. A Drugs@FDA query for the generic name retatrutide returns no approved product ^[4]. Under 21 U.S.C. 355, a new drug can't be introduced into interstate commerce without an approved application, which is the basic statutory reason retatrutide is unavailable outside a trial ^[8]. Second, section 503A compounding requires a bulk substance to satisfy a strict cascade: an applicable USP or NF monograph, or (if no monograph exists) status as a component of an FDA-approved drug, or (only if neither applies) inclusion on the 503A Bulks List ^[3]. The statute is specific here: a substance must comply "if such drug substance complies with the standards of an applicable United States Pharmacopoeia or National Formulary monograph" ^[3]. Retatrutide satisfies none of the three prongs. It has no monograph, it's not a component of an approved drug, and it's absent from the six-item bulks list at 21 CFR 216.23 ^[5]. Third, even setting the ingredient question aside, 503A separately demands that the bulk substance be manufactured by a section 510-registered establishment and shipped with a valid certificate of analysis ^[3]. Gray-market retatrutide, typically sold labeled "research use only," fails this requirement on its own regardless of the monograph question. And fourth, the 503B list (which governs outsourcing facilities rather than standard 503A pharmacies) is a separate roster under 21 CFR 216.24, and it likewise doesn't include retatrutide ^[9]. There's no back door through outsourcing facilities either. So when someone asks why their local compounding pharmacy won't touch retatrutide, the answer isn't caution or liability-shyness. It's that the law gives the pharmacy no lawful pathway at all. For a full breakdown of the buy-side legal questions, see retatrutide peptide buy.

Does a 'research use only' label make gray-market retatrutide legal to use?

No. FDA has been direct about this. Intended use of a product is established by "labeling claims, advertising matter, or oral or written statements by such persons or their representatives," per 21 CFR 201.128 ^[10], which means what the seller says about the product, not a disclaimer buried in the fine print, is what determines its regulatory status. In a March 2026 warning letter to Gram Peptides (MARCS-CMS 721806), FDA wrote that despite a research-use-only or not-for-human-consumption label, "evidence from the company's website established that its products were intended to be drugs for human use," and the letter specifically named retatrutide marketed on that site ^[11]. In plain terms: if the product page talks about weight loss, dosing schedules, or therapeutic benefit, that marketing language is what counts, and the disclaimer doesn't erase it. This matters for anyone reading a vendor's dosage chart and assuming the "not for human consumption" language means the seller is somehow operating within a gray but legal zone. FDA's own enforcement position says otherwise, and it's the same legal theory the agency has used for years against unapproved peptide sellers.

Could retatrutide get added to the 503A compounding list soon?

It's possible eventually, but nothing currently in motion covers retatrutide specifically, and the process, even for other peptides, is slow and non-binding at the advisory stage. FDA's Pharmacy Compounding Advisory Committee met on July 23 and 24, 2026, to consider seven peptides for the 503A Bulks List: BPC-157, KPV, TB-500, MOTS-c, emideltide (DSIP), semax, and epitalon ^[12]. Retatrutide was not among the seven, and it has never been nominated for that list at all ^[12]. Even for the substances that were considered, a favorable committee vote wouldn't create an automatic pathway. FDA advisory committee recommendations are non-binding, and actually adding a substance to the 503A Bulks List requires full notice-and-comment rulemaking ^[12], a process that routinely takes years from nomination to final rule. Retatrutide isn't in that pipeline at all right now. If it were nominated tomorrow, you'd still be looking at a multi-year process before any lawful compounding pathway could exist, if it ever did. FDA maintains a public list of bulk substances nominated for compounding consideration under 503A, sorted into interim categories, and retatrutide does not appear on it ^[13]. The agency's nominations document, which records the Category 1, 2, and 3 rosters as of its stated revision date, is the authoritative source for checking a substance's status at any given time ^[14].

What lawful alternatives exist while retatrutide remains investigational?

If you're looking at a retatrutide dosing chart because you want meaningful weight loss and a doctor's involvement, there are approved options on the market right now, with published safety and efficacy data behind them, unlike retatrutide. Semaglutide is approved and marketed as OZEMPIC and WEGOVY. Tirzepatide is approved as MOUNJARO and ZEPBOUND ^[4]. Both give clinicians a lawful incretin-based option with FDA-reviewed labeling, dosing schedules, and post-market safety monitoring. Semaglutide is a GLP-1 receptor agonist only; tirzepatide hits both GIP and GLP-1 receptors; retatrutide is a triple agonist at GIP, GLP-1, and glucagon receptors, which is the mechanistic reason its trial data looks more dramatic on paper, but that mechanism has not yet been through the full approval process ^[2]. More recently, orforglipron, an oral GLP-1 receptor agonist, was approved as FOUNDAYO under NDA 220934, in six strengths ranging from 0.8mg to 17.2mg ^[15]. That gives patients who don't want an injectable, or who were specifically drawn to investigational compounds because they wanted to avoid needles, an approved oral incretin option that didn't exist a couple of years ago. NIDDK, the federal government's diabetes and digestive disease research institute, publishes general guidance on evidence-based weight management that's a reasonable neutral starting point if you're weighing options with a primary care doctor or endocrinologist . None of this replaces a conversation with a clinician who knows your history, but it's a genuinely lawful starting point, which gray-market retatrutide is not. For a broader look at what retatrutide does in the body and how its trial results compare to approved drugs, the retatrutide peptide page and the how to take retatrutide peptide explainer both go deeper on the mechanism side. For safety concerns specifically, see retatrutide side effects.

What should you actually do if you're considering retatrutide right now?

Skip the vendor dosage charts. They're not backed by verifiable manufacturing, and no amount of careful math around bac water volumes fixes an unverifiable product. If you want to actually take retatrutide under medical supervision, the only legitimate route is enrollment in one of its registered clinical trials, such as NCT04881760, NCT05929066, or NCT05882045 ^{[2] [6] [7]}. Trial enrollment comes with monitoring, informed consent, and access to real drug under controlled conditions, none of which a gray-market purchase gives you. If you want weight loss now, talk to a doctor about semaglutide, tirzepatide, or orforglipron, all FDA-approved with published dosing and safety data ^{[4] [15]}. None of them will produce the 24.2% figure retatrutide showed at 12mg in its phase 2 trial ^[2], but they're legal, monitored, and backed by an approval process retatrutide simply hasn't completed yet. That gap may close eventually. It hasn't closed now, and no dosage chart changes that fact.

Frequently asked questions

What is the highest dose of retatrutide tested in clinical trials?

The phase 2 obesity trial (NCT04881760) tested maintenance doses up to 12mg weekly by subcutaneous injection. That arm produced a mean 24.2% weight reduction at 48 weeks, compared with 2.1% for placebo, according to the NEJM publication by Jastreboff et al., 2023.

How much bac water do you need for 10mg retatrutide?

There is no sanctioned reconstitution instruction for retatrutide at any strength, because no approved retatrutide product exists. Any specific bac water volume you see online for a 10mg vial comes from vendor marketing or informal guides, not from a verified manufacturing or clinical protocol.

How long will 10mg of retatrutide last once reconstituted?

There's no published, reviewed stability data for reconstituted retatrutide at any dose, since no approved product with a labeled beyond-use date exists. Approved peptides like semaglutide and tirzepatide carry FDA-reviewed stability instructions on their labels; retatrutide has no equivalent.

Is retatrutide FDA approved?

No. A Drugs@FDA search for the generic name retatrutide returns no approved product for any indication. It remains an investigational compound studied only in registered clinical trials, including NCT04881760, NCT05929066, and NCT05882045.

Can a compounding pharmacy legally make retatrutide?

No. Section 503A requires a bulk substance to meet a strict cascade (USP/NF monograph, component of an approved drug, or presence on the 503A Bulks List). Retatrutide meets none of these, and it is absent from the six-substance 503A Bulks List at 21 CFR 216.23.

Does a 'research use only' label make retatrutide legal to buy and use?

No. FDA determines intended use from labeling claims and advertising, not disclaimers. A March 2026 warning letter to Gram Peptides found that website claims established retatrutide products were intended as drugs for human use, despite research-use-only labeling.

What's the difference between retatrutide, semaglutide, and tirzepatide?

Semaglutide (OZEMPIC, WEGOVY) is a GLP-1 receptor agonist only. Tirzepatide (MOUNJARO, ZEPBOUND) hits GIP and GLP-1 receptors. Retatrutide is a triple agonist acting at GIP, GLP-1, and glucagon receptors, a mechanism studied in trials but not yet FDA approved.

Is retatrutide 30mg or 20mg a real studied dose?

No. The published phase 2 trial tested 1mg, 4mg, 8mg, and 12mg weekly maintenance doses. Products marketed at 20mg or 30mg are vendor packaging choices, not doses that appear in the published clinical trial record.

Will retatrutide ever be added to the 503A compounding list?

It's not currently under consideration. FDA's July 2026 advisory committee reviewed seven other peptides for the 503A list; retatrutide was not among them and has never been nominated. Even a favorable vote wouldn't create a pathway without formal notice-and-comment rulemaking.

What are the lawful alternatives to retatrutide right now?

Approved incretin options include semaglutide (OZEMPIC, WEGOVY), tirzepatide (MOUNJARO, ZEPBOUND), and the oral GLP-1 agonist orforglipron (FOUNDAYO, NDA 220934, six strengths from 0.8mg to 17.2mg). All have published dosing schedules and safety monitoring that retatrutide currently lacks.

Can I legally import retatrutide from overseas for personal use?

FDA publishes a personal importation policy that governs unapproved drugs brought in from abroad, and it does not create a general right to import investigational compounds like retatrutide for personal use. The underlying drug status and approval gaps still apply regardless of the source country.

Where does retatrutide dosage data actually come from if not from an approved label?

The only credible dosage data comes from registered clinical trials on ClinicalTrials.gov, primarily NCT04881760, with additional later-phase records at NCT05929066 and NCT05882045. Results from the phase 2 trial were published in the New England Journal of Medicine in 2023.

Sources

1. ClinicalTrials.gov, NCT04881760: Retatrutide's development code LY3437943 and trial title, registering the phase 2 obesity study
2. Jastreboff AM et al., New England Journal of Medicine, 2023: Trial dose arms (1mg, 4mg, 8mg, 12mg), 24.2% mean weight loss at 12mg vs 2.1% placebo at 48 weeks, weekly subcutaneous route, triple receptor mechanism
3. 21 U.S.C. 353a(b)(1)(A)(ii)-(iii): 503A requires bulk substances be made by a section 510-registered establishment and accompanied by a valid certificate of analysis
4. Drugs@FDA, FDA-approved drug products database: Semaglutide and tirzepatide are FDA-approved as OZEMPIC/WEGOVY and MOUNJARO/ZEPBOUND; retatrutide has no approved product
5. 21 CFR 216.23, eCFR current through 2026-07-08: The complete 503A Bulks List contains six named substances, no peptide, and does not include retatrutide
6. ClinicalTrials.gov, NCT05929066 / NCT04881760 diabetes program: Retatrutide has advanced into later-phase registered trials with published enrollment criteria and endpoints, and studied type 2 diabetes indications beyond obesity
7. ClinicalTrials.gov, NCT05882045: A second later-phase retatrutide trial registration providing an independent record of dosing and design
8. 21 U.S.C. 355: A new drug cannot be introduced into interstate commerce without an approved application
9. 21 CFR 216.24: The separate 503B bulks list for outsourcing facilities also does not include retatrutide
10. 21 CFR 201.128: Intended use is established by labeling claims, advertising, and seller statements, not by disclaimers
11. Federal Register, Docket FDA-2025-N-6895, published 16 April 2026: The July 2026 advisory committee considered seven peptides for the 503A list, not including retatrutide, and advisory recommendations are non-binding requiring rulemaking
12. FDA, Bulk Drug Substances Used in Compounding Under Section 503A: FDA's public list of nominated bulk substances for 503A compounding does not include retatrutide
13. FDA, Bulk Drug Substances Nominated for Use in Compounding (PDF): FDA's nominations document records Category 1, 2, and 3 rosters as the authoritative source for a substance's interim compounding status
14. Drugs@FDA, FDA-approved drug products database, NDA 220934: Orforglipron was approved as FOUNDAYO under NDA 220934 in six strengths from 0.8mg to 17.2mg
15. NIDDK, Weight Management: NIDDK publishes federal guidance on evidence-based weight management as a neutral reference point