doses, as the trials administered them.
What doses have been studied, and how the trials handled escalation
This is a description of the dose ranges and titration schedules used in published retatrutide trials. It is not dosing guidance. No clinician can write a prescription for retatrutide today.
A note on this page
The doses below describe how retatrutide was administered to volunteers in published clinical trials — not a dosing recommendation for anyone reading this page. There is no approved dose, no labeled product, and no clinician who can write a schedule for retatrutide today.
That said, the trial record is specific. Phase 1 established tolerability across 0.5 to 12 mg once weekly. Phase 2 tested 1, 4, 8, and 12 mg in the obesity cohort and added a 0.5 mg low arm in the diabetes trial. Phase 3 narrowed to three maintenance options: 4, 9, and 12 mg once weekly, always reached via a stepwise escalation starting at 2 mg.
The reason for once-weekly dosing is a six-day terminal half-life — a property engineered into the molecule by attaching a fatty acid that binds to circulating albumin and slows clearance dramatically. That engineering is what separates retatrutide from native glucagon-family peptides, which clear in minutes.
About this page
The doses below are drawn from published Phase 1, Phase 2, and Phase 3 retatrutide trials [1][2][3][7]. They describe how the molecule was studied in human volunteers and participants under clinical supervision in a regulated trial setting. They are not a dosing schedule for anyone outside such a trial.
There is no labeled product, no prescriber's information, no FDA-approved dose, and no compounding-pharmacy route. Visitors who encounter retatrutide for sale from research-chemical vendors should understand that such material is not produced to clinical standards and carries no verification of identity, purity, or sterility. Vendors describing it as 'research only' are stating an accurate legal frame; that frame does not include human dosing.
Doses tested in the Phase 1 first-in-human study
The Phase 1 single-ascending-dose study (NCT04143802) tested doses from 0.5 mg through 12 mg subcutaneously in healthy volunteers, followed by a multiple-ascending-dose arm using the same range delivered weekly [7]. Pharmacokinetics were dose-proportional. The terminal elimination half-life was approximately 6 days, with steady-state concentrations reached after roughly four weekly doses. The Phase 1 study established that the molecule could be administered subcutaneously, that the long half-life supported a weekly schedule, and that the safety signal at single doses up to 12 mg was tolerable enough to proceed to Phase 2.
Phase 2 dose ranges
The Phase 2 obesity trial (Jastreboff 2023, NEJM) randomized participants to 1, 4, 8, or 12 mg weekly versus placebo, with a dose-escalation schedule used to reach the target dose [1]. Escalation started low and stepped up at four-week intervals, a strategy borrowed from the broader incretin class to reduce the gastrointestinal adverse-event burden that accompanies rapid dose increases.
The Phase 2 type-2-diabetes trial (Rosenstock 2023, Lancet) used 0.5, 4, 8, and 12 mg weekly with similar escalation, and added a dulaglutide 1.5 mg active comparator alongside placebo [2].
The Phase 2a MASLD substudy (Sanyal 2024, Nature Medicine) used the same four-dose obesity ladder (1, 4, 8, 12 mg) over 48 weeks, with MRI-PDFF as the primary readout [3].
Phase 3 maintenance doses
The TRIUMPH Phase 3 program narrowed the dose set to three maintenance options: 4 mg, 9 mg, and 12 mg weekly [15]. The 9 mg arm was added between Phase 2 and Phase 3 to provide a middle option between the moderate (4 mg) and high (12 mg) doses. TRIUMPH-1 reported the 12 mg arm at 28.3% mean weight loss over 80 weeks; TRIUMPH-4 reported the 12 mg arm at 28.7% over 68 weeks [5][6]. The 9 mg arm in TRIUMPH-4 produced lower-magnitude effects with fewer dysesthesia events [14].
All Phase 3 dosing has used dose escalation. The exact step schedule varies modestly by trial, but the common pattern is: a 2 mg starting dose for four weeks, then stepwise increases at four-week intervals to reach the assigned maintenance dose. The escalation is designed to minimize nausea, vomiting, and diarrhea during the initial weeks, which are the predominant adverse-event window.
Pharmacokinetics in a sentence
Once-weekly subcutaneous administration. Approximately 6-day terminal half-life [7]. Linear, dose-proportional plasma concentrations across the 0.5 to 12 mg range. Steady-state concentrations reached after approximately four weekly doses, which is why clinical effects typically begin to consolidate around the four-to-eight-week mark in trial cohorts. The albumin-binding C20 diacid fatty acid moiety is the engineering feature that produces this profile; without it, the underlying glucagon-family peptide would have a half-life of minutes.
Adverse events along the dose curve
Gastrointestinal adverse events — nausea, diarrhea, vomiting, constipation — were the most common adverse effects in every Phase 2 and Phase 3 readout, concentrated during dose escalation and predominantly mild to moderate in severity [8]. Nausea incidence reached approximately 60% on the 12 mg arm of the Phase 2 obesity trial against approximately 10% on placebo. Most events resolved during titration as participants reached their maintenance dose.
Heart rate rose by approximately 5 to 10 beats per minute in a dose-dependent pattern, peaking around week 24 and partially declining thereafter [9]. Blood pressure fell across all doses, with the largest systolic reduction (approximately 9.1 mmHg) reported in the 8 mg arm of pooled Phase 2 data [10]; TRIUMPH-4 reported 14.0 mmHg systolic reduction on the 12 mg arm at 68 weeks [6].
Cutaneous dysesthesia — an abnormal tingling, burning, or prickling sensation in the skin — was reported in approximately one in five participants on 12 mg in TRIUMPH-4, at lower frequency on 9 mg, and was generally mild and self-limited [14]. It is a distinctive signal that has not been characteristic of mono- or dual-agonist incretin molecules. The mechanism is under investigation.
What the dose record does not establish
The trials have not characterized retatrutide in pregnancy, lactation, pediatric populations, or in patients with severe renal or hepatic impairment. Long-term dosing beyond approximately 80 to 104 weeks of continuous exposure is unstudied; cessation strategies and maintenance-dose adjustment over multi-year horizons are not yet in the public literature. Body-composition substudies addressing lean-mass preservation under glucagon-receptor agonism are ongoing.
All of the dose information above is published in the context of supervised clinical trials with screening, monitoring, adjudicated adverse-event reporting, and clinical-grade material produced to GMP standards. It does not generalize to material obtained outside that setting.