Retatrutide Dosage: Trial Doses, Titration and Chart
Medically reviewed by Juan Pablo Frías, MD · · DisclosureGLP-1 / GIP / glucagon triple agonistUpdated
- Doses studied
- 1–12 mg
- once weekly, phase 2
- Starting dose
- 2 or 4 mg
- groups above 1 mg; the 12 mg group started at 2 mg
- Half-life
- approximately 6 days
- subcutaneous, in people · Lancet 2022, PMID 36354040
Doses studied in clinical trials
The phase 2 obesity trial gave once-weekly doses of 1, 4, 8 or 12 mg, or placebo, for 48 weeks. The 4 mg and 8 mg doses each had two groups, one starting at 2 mg and one at 4 mg; their results below are the two groups combined. The 12 mg group started at 2 mg and stepped up through 4 and 8 mg.
Phase 2 figures · verify before publishing
| Weekly dose | Start | Escalation | Weight change, 48 wk |
|---|---|---|---|
| Placebo | — | — | −2.1% |
| 1 mg | 1 mg | None | −8.7% |
| 4 mg | 2 or 4 mg | 2 → 4 mg, or none | −17.1% |
| 8 mg | 2 or 4 mg | 2 → 4 → 8 mg, or 4 → 8 mg | −22.8% |
| 12 mg | 2 mg | 2 → 4 → 8 → 12 mg | −24.2% |
Source: Jastreboff AM et al., New England Journal of Medicine 2023;389:514–526 (phase 2; PMID 37366315; ClinicalTrials.gov NCT04881760). Least-squares mean change at 48 weeks; the 4 mg and 8 mg rows combine both starting-dose groups. The primary end point was at 24 weeks.
Doses used in published studies
Each dose below is quoted from a study abstract, strongest design first. Animal doses are labelled and do not translate directly to people. None of them is a recommendation.
| Dose | Frequency and route | Study type | Source |
|---|---|---|---|
| 4 mg, 9 mg or 12 mg | once weekly · subcutaneous · 80 weeks | Human RCTn = 2339 | The New England journal of medicine 2026, PMID 42814954 |
| 4 mg, 9 mg or 12 mg | once weekly · subcutaneous · 80 weeks | Human RCTn = 1152 | Lancet 2026, PMID 42810372 |
| 4 mg, 9 mg or 12 mg | once weekly · subcutaneous · 40 weeks | Human RCTn = 537 | Lancet 2026, PMID 42250575 |
| 0.5/1, 4, 8, 12 mg | once weekly · subcutaneous · 36 weeks (Study 1) and 48 weeks (Study 2) | Human controlled trial | Diabetes, obesity & metabolism 2026, PMID 42608321 |
| 0.5, 4, 8 or 12 mg vs dulaglutide 1.5 mg or placebo | once weekly · subcutaneous · 36 weeks | Human RCTn = 189 | The lancet. Diabetes & endocrinology 2025, PMID 40609566 |
| 0.5, 4, 8 or 12 mg vs dulaglutide 1.5 mg or placebo | once weekly · subcutaneous · 36 weeks | Human RCTn = 275 | Diabetes, obesity & metabolism 2025, PMID 40916752 |
| 1, 4, 8 or 12 mg | once weekly · subcutaneous · 48 weeks (liver fat measured at 24 weeks) | Human RCTn = 98 | Nature medicine 2024, PMID 38858523 |
| 1, 4, 8 or 12 mg (4 mg and 8 mg groups with 2 mg or 4 mg initial dose) | once weekly · subcutaneous · 48 weeks | Human RCTn = 338 | The New England journal of medicine 2023, PMID 37366315 |
| 0.5, 4, 8 or 12 mg (various escalation schemes) vs dulaglutide 1.5 mg or placebo | once weekly · subcutaneous · 36 weeks (primary endpoint at 24 weeks) | Human RCTn = 281 | Lancet 2023, PMID 37385280 |
| 0.5, 1.5, 3, 3/6 or 3/6/9/12 mg of LY3437943 (retatrutide) vs placebo or dulaglutide 1.5 mg | once weekly · subcutaneous · 12 weeks | Human RCTn = 72 | Lancet 2022, PMID 36354040 |
Example titration schedule
This is the dose sequence in the trial's 12 mg group, as registered on ClinicalTrials.gov. It shows the pattern, not a recommendation. How many weeks each step lasted is pending a check against the full paper.
Step 1 (start)2 mg
Step 24 mg
Step 38 mg
Step 4 (target)12 mg
- 1Step 1 (start)2 mg
- 2Step 24 mg
- 3Step 38 mg
- 4Step 4 (target)12 mg
Dose to syringe units
For a 10 mg vial mixed with 2 mL of bacteriostatic water (5 mg/mL), on a U-100 syringe. These are reference amounts for the math, not suggested doses.
- 0.5 mg
- 10 u
- 1 mg
- 20 u
- 2 mg
- 40 u
- 4 mg
- 80 u
Before anyone considers it
- Retatrutide is investigational. It is not FDA approved for any use.
- Products sold online as research chemicals are not checked by the FDA for identity, purity or dose.
- The most common side effects in the trial were stomach and gut problems. They rose with dose, were mostly mild to moderate, and were partly reduced by starting at 2 mg instead of 4 mg.
- Higher doses raised heart rate in the trial. People with heart conditions need medical advice first.
Common questions
What is the starting dose of Retatrutide in trials?
Groups above 1 mg started at 2 mg or 4 mg and stepped up through set dose levels (for example 2, 4, 8, then 12 mg). That is the trial design, not a recommendation.
How many units is 2 mg of Retatrutide?
It depends on the water added. A 10 mg vial with 2 mL of water gives 5 mg/mL, so 2 mg is 40 units on a U-100 syringe. Use the calculator for other mixes.
Is Retatrutide taken weekly?
Yes. The trials dosed it once a week.
Is Retatrutide FDA approved?
No. Retatrutide is investigational (investigational · phase 3) and not approved for any use.
More on Retatrutide
Side effectsWhat labels and studies report, and what is unknown.CalculatorVial, water and dose to syringe units.ResultsStudy outcomes and when they were measured.PricePrice per mg and per week from dated listings. No vendor links.Legal statusFDA, compounding and WADA status with dates.How to injectSites, syringe types and hygiene, step by step.
Sources
- 1Triple-Hormone-Receptor Agonist Retatrutide for Obesity: A Phase 2 Trial (Jastreboff AM et al.)New England Journal of Medicine · 2023PMID 37366315Accessed 2 Oct 2026
- 2Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity (TRIUMPH-1; Jastreboff AM et al.)New England Journal of Medicine · 2026PMID 42814954Accessed 2 Oct 2026
- 3A Phase 2 Study of Once-Weekly LY3437943 Compared With Placebo in Participants Who Have Obesity or Are Overweight With Weight-Related Comorbidities (NCT04881760; arms and posted results)ClinicalTrials.gov (U.S. National Library of Medicine) · 2021clinicaltrials.govAccessed 2 Oct 2026
- 4Warning letter to NuScience Peptides LLC (ref. 733652), 24 Aug 2026, one of five letters to research-peptide sellers issued that dayU.S. Food and Drug Administration · 2026fda.govAccessed 2 Oct 2026
- 5Metric (SI) Prefixes (NIST Reference on Constants, Units, and Uncertainty)National Institute of Standards and Technology (NIST) · 2025physics.nist.govAccessed 2 Oct 2026
- 6BASAGLAR (insulin glargine) injection, prescribing information (DailyMed)U.S. Food and Drug Administration / DailyMed (Eli Lilly and Company label) · 2026dailymed.nlm.nih.govAccessed 2 Oct 2026
- 7Retatrutide in adults with obesity and type 2 diabetes (TRIUMPH-2): a double-blind, parallel-group, randomised, placebo-controlled, phase 3 trial.Lancet (London, England) · 2026PMID 42810372Accessed 2 Oct 2026
- 8Efficacy and safety of retatrutide, a GIP, GLP-1, and glucagon receptor agonist, in people with type 2 diabetes and inadequate glycaemic control with diet and exercise (TRANSCEND-T2D-1): a double-blind, randomised, phase 3 trial.Lancet (London, England) · 2026PMID 42250575Accessed 2 Oct 2026
- 9Retatrutide-Associated Improvements in Cardiovascular Risk Biomarkers in Adults With Obesity With or Without Type 2 Diabetes.Diabetes, obesity & metabolism · 2026PMID 42608321Accessed 2 Oct 2026
- 10Effects of retatrutide on body composition in people with type 2 diabetes: a substudy of a phase 2, double-blind, parallel-group, placebo-controlled, randomised trial.The lancet. Diabetes & endocrinology · 2025PMID 40609566Accessed 2 Oct 2026
- 11Appetite, eating attitudes, and eating behaviours during treatment with retatrutide in adults with type 2 diabetes: Results of a phase 2 study.Diabetes, obesity & metabolism · 2025PMID 40916752Accessed 2 Oct 2026
- 12Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial.Nature medicine · 2024PMID 38858523Accessed 2 Oct 2026
- 13Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial conducted in the USA.Lancet (London, England) · 2023PMID 37385280Accessed 2 Oct 2026
- 14LY3437943, a novel triple GIP, GLP-1, and glucagon receptor agonist in people with type 2 diabetes: a phase 1b, multicentre, double-blind, placebo-controlled, randomised, multiple-ascending dose trial.Lancet (London, England) · 2022PMID 36354040Accessed 2 Oct 2026
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