Retatrutide Microdosing vs Clinical-Trial Dosing
Clinical trials studied retatrutide at doses of 4 mg, 8 mg, and 12 mg (Phase 2) and 4 mg, 9 mg, and 12 mg (TRIUMPH-1 Phase 3). Microdosing — using doses below the lowest studied trial arm — has not been studied in any published clinical trial. Efficacy and safety at sub-trial doses are unknown.
Dose-Efficacy Relationship from Phase 2
| Dose | Weight Loss at 24 Weeks (Phase 2) | Evidence Status | Notes |
|---|---|---|---|
| Sub-4 mg ("microdose") | Not studied | No evidence | Anecdotal use only; no clinical data |
| 4 mg/week | ~8.7% | Phase 2 RCT | Lowest studied therapeutic arm |
| 8 mg/week | ~12.9% | Phase 2 RCT | Mid-dose arm |
| 12 mg/week | ~17.5% | Phase 2 RCT | Highest dose arm; highest efficacy and highest GI AE rate |
Phase 2 data from Jastreboff et al., NEJM 2023. Approximate values at 24 weeks. Phase 3 TRIUMPH-1 studied 4/9/12 mg arms; 80-week topline data available.
What Microdosing Means in Practice
In online communities, "microdosing" typically refers to doses below 4 mg weekly — often 0.25–2 mg. These doses have not been studied in clinical trials. The dose-dependent efficacy relationship from Phase 2 suggests that lower doses produce less weight loss. Whether sub-4 mg doses produce any meaningful weight loss is unknown.
For a complete review of microdosing, see the Retatrutide Microdosing hub page.
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