Retatrutide has no label, so it has no labelled schedule. What it has instead is a set of trial ladders, recorded with different amounts of detail in different places. The phase 2 trials put their ladders in the public registry, arm by arm. The phase 3 trials did not: their registry entries say "Dose 1", "Dose 2" and "Dose 3", and the doses are known from Eli Lilly's releases. A schedule circulating online can be checked against both, and this page sets them out with each step converted into syringe units.
The single-figure dosage page, with the weight results and the unit table for every vial size, is retatrutide dosage. Medibact's Retatrutide guide covers the molecule and its evidence. The once-weekly interval the trials used rests on the half-life set out on retatrutide's half-life page.
The ladders the phase 2 trials registered
Both phase 2 trials ran several escalation ladders in parallel, which is how Lilly compared starting doses. ClinicalTrials.gov records each arm's sequence (read 2026-10-14):
| Arm (maintenance dose) | Obesity trial NCT04881760 (338 participants) | Type 2 diabetes trial NCT04867785 (281 participants) |
|---|---|---|
| 0.5 mg fixed | — | 0.5 mg throughout |
| 1 mg fixed | 1 mg throughout | — |
| 4 mg, start 2 mg | 2 → 4 mg | 2 → 4 mg |
| 4 mg, no escalation | 4 mg throughout | 4 mg throughout |
| 8 mg, start 2 mg | 2 → 4 → 8 mg | 2 → 4 → 8 mg |
| 8 mg, start 4 mg | 4 → 8 mg | 4 → 8 mg |
| 12 mg, start 2 mg | 2 → 4 → 8 → 12 mg | 2 → 4 → 8 → 12 mg |
| Comparator | placebo | placebo and dulaglutide 1.5 mg |
Every arm is described as a once-weekly subcutaneous injection. The obesity trial ran 48 weeks (Jastreboff et al., NEJM 2023); the diabetes trial's endpoints were at 24 and 36 weeks (Rosenstock et al., Lancet 2023). The registry and the two abstracts give the order of the steps but not the week each step began.
The two starting points were compared on purpose. The obesity paper reports that gastrointestinal adverse events were dose-related and "partially mitigated with a lower starting dose (2 mg vs. 4 mg)", and the diabetes paper states that its data "informed dose selection for the phase 3 programme". The 8 mg arms started at 2 mg and at 4 mg in both trials so that the two could be set side by side.
What the phase 3 registry entries leave out
Read on 2026-10-14, the ClinicalTrials.gov entries for TRIUMPH-1 (NCT05929066, 2,335 enrolled), TRIUMPH-2 (NCT05929079, 1,152), TRIUMPH-3 (NCT05882045, 1,946) and TRIUMPH-4 (NCT05931367, 445) list their arms as "Retatrutide Dose 1", "Dose 2" and, where there are three, "Dose 3", each described only as "Participants will receive retatrutide subcutaneously (SC)". None had posted results. The registry, the public document a schedule would normally be checked against, does not contain the phase 3 doses or the interval between steps.
Those come from the sponsor. Eli Lilly's release of 2026-05-21 on TRIUMPH-1 reports maintenance doses of 4, 9 and 12 mg, a 4 mg arm that needed one escalation step, and a 12 mg arm that rose through 2, 4, 6 and 9 mg; its release of 2026-07-23 on TRIUMPH-2 and TRIUMPH-3 states that participants started at 2 mg once weekly and increased every four weeks. Both releases were read by this site on 2026-09-18 and are cited on retatrutide dosage; the distribution site did not answer on 2026-10-14, so they could not be re-opened for this page, and their figures are reported as read in September.
| Phase 3 arm (per Lilly) | Steps described | Weeks to reach the dose at four weeks a step (arithmetic) |
|---|---|---|
| 4 mg | 2 → 4 mg | from week 5 |
| 9 mg | 2 → 4 → 6 → 9 mg | from week 13 |
| 12 mg | 2 → 4 → 6 → 9 → 12 mg | from week 17 |
The third column is arithmetic on the four-week interval Lilly states, not a published figure. The 9 mg ladder is inferred from the 12 mg one, which passes through 9 mg; the releases do not print the 9 mg arm's steps separately.
The ladder on DailyMed, and why it differs
A DailyMed search for retatrutide on 2026-10-14 returned ten records, all filed by Guangzhou Yixin Cross-border E-commerce Co., Ltd. and published on 2025-11-17. The one titled "RETATRUTIDE LYOPHILIZED POWDER" prints a "typical weekly dosing schedule": 0.25 mL (2.5 mg) for weeks 1–4, 0.5 mL (5 mg) for weeks 5–8, 0.75 mL (7.5 mg) for weeks 9–12 and 1 mL (10 mg) from week 13, at 10 mg/mL.
That ladder — 2.5 mg, then 2.5 mg increments every four weeks — is the Zepbound and Mounjaro label ladder for tirzepatide, set out step by step for both brands. It matches no retatrutide trial: no registered arm used 2.5, 5, 7.5 or 10 mg. The record is a labeler's own listing; DailyMed indexes such documents without regulatory review, and it is not an approval. It ranks for "retatrutide dosing schedule", which is why it is reported here.
Each step in syringe units
Research-market retatrutide is sold in 5, 10 and 20 mg vials. The table converts every amount used in the trials above into U-100 units (100 units = 1 mL) at three concentrations: 5 mg/mL (10 mg + 2 mL, or 5 mg + 1 mL), 10 mg/mL (10 mg + 1 mL, or 20 mg + 2 mL) and 20 mg/mL (20 mg + 1 mL). Going the other way, from a syringe reading back to milligrams, is the units-to-mg table for retatrutide.
| Trial amount | Where it appears | 5 mg/mL | 10 mg/mL | 20 mg/mL |
|---|---|---|---|---|
| 0.5 mg | phase 2 fixed arm (diabetes) | 10 | 5 | 2.5 |
| 1 mg | phase 2 fixed arm (obesity) | 20 | 10 | 5 |
| 2 mg | first step, phase 2 and phase 3 | 40 | 20 | 10 |
| 4 mg | step and maintenance | 80 | 40 | 20 |
| 6 mg | phase 3 step | 120 (>1 syringe) | 60 | 30 |
| 8 mg | phase 2 step and maintenance | 160 (>1 syringe) | 80 | 40 |
| 9 mg | phase 3 step and maintenance | 180 (>1 syringe) | 90 | 45 |
| 12 mg | maintenance | 240 (>1 syringe) | 120 (>1 syringe) | 60 |
Read as sentences: at 10 mg/mL the phase 3 ladder is 20, 40, 60, 90 and 120 units; at 20 mg/mL it is 10, 20, 30, 45 and 60 units. At 5 mg/mL every amount above 4 mg needs more than one syringe, and the whole 5 mg vial holds less than the 6 mg step. The same arithmetic for any vial and volume is in the retatrutide reconstitution calculator, and water volumes per vial size are on reconstituting retatrutide. How a weekly amount divides into a vial over the weeks of a ladder is on doses per vial.
What the schedule questions ask, answered as record
- "Every 5 days." Every arm in every registry entry read for this page is once weekly. No trial used a five-day interval.
- Microdosing. Below 2 mg, the record holds two fixed arms, 0.5 mg and 1 mg, each kept for the whole trial. The obesity trial's 1 mg arm lost 8.7% of body weight at 48 weeks against 2.1% on placebo (NEJM 2023). Neither was a starting step.
- A missed dose. No retatrutide document read for this page states a missed-dose rule. The Zepbound rule for tirzepatide (within four days, otherwise skip) is that drug's label and does not transfer.
- Switching from another drug. The phase 3 exclusion rules for recent tirzepatide and semaglutide users are on moving from tirzepatide to retatrutide and semaglutide to retatrutide.
What this page does not establish
It reports trial ladders as history. It does not recommend a starting amount, a step, an interval or a maintenance dose, and the phase 3 figures rest on sponsor releases rather than on registry entries or peer-reviewed results, which had not been published for TRIUMPH when this page was written. The trial populations had obesity, type 2 diabetes or cardiovascular disease, were screened and were monitored; a research vial carries none of that. How the trials gave the injections is on how retatrutide is injected, and the ladder set against tirzepatide's label is on retatrutide vs tirzepatide dosage.
Sources and dates
Opened 2026-10-14: ClinicalTrials.gov API records for NCT04881760, NCT04867785, NCT05929066, NCT05929079, NCT05882045 and NCT05931367 (arm descriptions, enrolment, results status); the PubMed abstracts of Jastreboff et al., NEJM 2023 (PMID 37366315) and Rosenstock et al., Lancet 2023 (PMID 37385280); the DailyMed SPL search for retatrutide and the "RETATRUTIDE LYOPHILIZED POWDER" record. Read 2026-09-18 and not re-opened: Eli Lilly's releases of 2026-05-21 and 2026-07-23 (PR Newswire). Units are arithmetic by this site. Corrections go to the contact page.