Retatrutide Dosing: What the Clinical Trials Used
Search interest in retatrutide dosing far outruns the published record, and a great deal of what circulates online cannot be traced back to any trial. This page covers only what was actually administered in registered clinical studies, with sources.
Retatrutide (LY3437943) is a once-weekly subcutaneous triple agonist acting on the GLP-1, GIP and glucagon receptors. Its half-life of roughly six days is what supports weekly administration.
Retatrutide doses studied in clinical trials
| Study | Population | Doses studied | Duration |
|---|---|---|---|
| Phase 2 (Jastreboff et al.) | Obesity | 1mg, 4mg, 8mg, 12mg weekly | 48 weeks |
| Phase 2 (Rosenstock et al.) | Type 2 diabetes | 0.5mg, 4mg, 8mg, 12mg weekly | 36 weeks |
| TRIUMPH-2 (Phase 3) | T2D with obesity or overweight | 4mg, 9mg, 12mg weekly | 80 weeks |
| TRIUMPH-3 (Phase 3) | Severe obesity with cardiovascular disease | 9mg, 12mg weekly | 80 weeks |
The Phase 3 programme narrowed the range that Phase 2 had explored: 12mg remained the top dose, the 8mg step became 9mg, and the 1mg arm was dropped entirely.
Results by dose level
TRIUMPH-2, at 80 weeks: 4mg produced 29.8 lbs (12.7%) mean weight reduction, 9mg produced 45.4 lbs (19.1%), and 12mg produced 49.6 lbs (20.8%). A1C fell by up to 1.6% at the highest dose.
TRIUMPH-3, at 80 weeks: 9mg produced 52.7 lbs (21.6%) and 12mg produced 55.8 lbs (22.6%).
The earlier Phase 2 obesity study reported mean weight reduction of up to 24.2% at 48 weeks on the 12mg dose.
Effect scales with dose across every study. So does the adverse-event burden, which is the reason none of the trials started participants at their target dose.
How the trials handled dose escalation
No study began at the target dose. Each used stepwise escalation over a period of weeks under clinical supervision, with different arms assigned different starting points and step sizes.
Gastrointestinal adverse events — nausea, vomiting and diarrhoea — were the most commonly reported in every trial, and were dose-dependent. Increases in heart rate were also observed at higher doses. Escalation exists to manage precisely those effects, alongside the monitoring and withdrawal criteria that a trial protocol provides and an uncontrolled setting does not.
Is retatrutide FDA approved?
No. As of September 2026, retatrutide is not approved by the FDA for any indication. Eli Lilly has stated it plans to submit a Biologics License Application on the strength of the TRIUMPH Phase 3 results in Q1 2027. Until that review concludes there is no approved label, no approved indication and no approved dose.
Why this is not a dosing protocol
Every figure on this page describes what a clinical trial administered to screened participants under medical supervision, with escalation schedules, monitoring and predefined withdrawal criteria. None of it constitutes a recommendation. Material supplied by MyGLP1Store is for laboratory research use only and is not for human consumption.
Retatrutide Dosing — Frequently Asked Questions
What doses of retatrutide were used in clinical trials?
Between 0.5mg and 12mg once weekly. The Phase 2 obesity trial studied 1, 4, 8 and 12mg; the Phase 3 TRIUMPH trials studied 4, 9 and 12mg.
Is there a standard retatrutide dosing schedule?
No. There is no approved label, so no standard schedule exists. The trials used stepwise escalation under clinical supervision, and the schedule differed between studies and between arms within a study.
How often was retatrutide administered?
Once weekly by subcutaneous injection, supported by a half-life of roughly six days.
What was the highest retatrutide dose studied?
12mg weekly, which was the top dose in both the Phase 2 and the Phase 3 programmes.
Is retatrutide FDA approved?
Not as of September 2026. Eli Lilly plans to file a Biologics License Application in Q1 2027.
Further reading
- Retatrutide research guide — triple-agonist mechanism and published trial data.
- What is retatrutide? A complete scientific overview.
- Retatrutide (LY3437943) — single vials, 10mg to 50mg.
- Bulk retatrutide — wholesale kits of 10 vials.