Retatrutide Dosage Chart
Phase 2 trial titration schedule (1, 4, 8, 12 mg) and what compounded retatrutide protocols typically follow.
Educational tool — not medical advice. This calculator provides estimates based on population averages and published trial data. Outputs are not clinical recommendations and do not replace evaluation by a qualified prescriber. Do not start, stop, or change a peptide therapy based on the result of this tool.
Retatrutide is a triple agonist of GLP-1, GIP, and glucagon receptors developed by Eli Lilly. As of April 2026 it is in late-stage trials and not yet FDA-approved — but it is widely available through compounding pharmacies and research-peptide channels. Phase 2 trial data (NEJM 2023) showed approximately 24% body-weight reduction at 12 mg over 48 weeks, the largest weight-loss effect ever published for an injectable.
Retatrutide at a Glance
| Trial doses (Phase 2) | 1 mg, 4 mg, 8 mg, or 12 mg subQ weekly |
|---|---|
| Phase 2 max dose | 12 mg/week |
| Route | Subcutaneous injection, once weekly |
| FDA status (April 2026) | Not FDA-approved. Phase 3 trials ongoing. Compounded versions are research-use, not approved for human therapy. |
| Mechanism | Triple agonist — GLP-1, GIP, and glucagon receptors |
| Reported efficacy | ~24% body-weight reduction at 48 weeks (12 mg arm, NEJM 2023) |
Retatrutide Dose Escalation Schedule
| Weeks | Dose | Notes |
|---|---|---|
| Weeks 1–4 | 0.5 mg | Trial-style starting dose for tolerability. |
| Weeks 5–8 | 1 mg | First step. Trial 1 mg arm holds here. |
| Weeks 9–12 | 2 mg | Bridge step toward higher trial arms. |
| Weeks 13–16 | 4 mg | Trial 4 mg arm holds here. Some compounded protocols stop at this tier. |
| Weeks 17–20 | 6 mg | Bridge step toward 8 mg. |
| Weeks 21–24 | 8 mg | Trial 8 mg arm holds here. Significant fat-loss tier. |
| Weeks 25–28 | 10 mg | Bridge step toward maximum. |
| Week 29+ | 12 mg | Phase 2 max dose. Significant GI side-effect burden at this tier. |
This schedule reconstructs Lilly's published trial titration. Compounded retatrutide is not FDA-approved and lacks regulated dosing guidance — actual clinical practice protocols vary. Many practitioners hold at 4 mg or 8 mg long-term rather than reach 12 mg.
Retatrutide Dosing by Use Case
Commonly cited protocols vary by what Retatrutide is being used for. The table below summarizes typical ranges reported in clinical practice and published literature.
| Use case | Typical dose | Frequency | Cycle length | Notes |
|---|---|---|---|---|
| Weight loss (research / off-label) | 4–12 mg | Once weekly | Indefinite while available; reassess regularly | Choose the lowest dose tier that achieves goals to minimize GI burden. |
Stacking Retatrutide
Retatrutide is not stacked with semaglutide or tirzepatide — overlapping GLP-1 activation creates compounded GI side effects without proportional benefit. It is occasionally combined with low-dose AOD-9604, but evidence for the combination is anecdotal.
Retatrutide is in late-stage trials but is not FDA-approved. The triple-receptor mechanism produces stronger efficacy and stronger GI side effects than current GLP-1 drugs.
- •Most common trial side effects: nausea, diarrhea, vomiting, constipation, decreased appetite. Severity scales with dose.
- •Glucagon agonism (the third receptor) raises theoretical concerns about heart rate elevation and increased hepatic glucose output — ongoing trials are evaluating long-term cardiovascular safety.
- •Pancreatitis risk class effect for GLP-1 agonists applies here.
- •No FDA black box warning yet — labeling will follow approval.
- •Compounded retatrutide is not subject to FDA manufacturing controls.
- •Active or recent malignancy
- •Personal or family history of medullary thyroid carcinoma (class effect concern)
- •MEN 2 syndrome
- •Pregnancy or planning pregnancy
- •Severe gastroparesis
Retatrutide Dosing FAQ
In Phase 2 trial data, retatrutide produced approximately 24% body-weight reduction at 12 mg over 48 weeks, compared to ~21% for tirzepatide at 15 mg over 72 weeks (SURMOUNT-1). The triple receptor agonism is the proposed mechanism for the larger effect. Head-to-head trials have not been published.
Compounded retatrutide is available, but it is not FDA-approved. Compounded versions of unapproved investigational drugs are a regulatory gray area — some pharmacies provide it as 'research-use,' which is distinct from approved compounded drug therapy.
Phase 3 trials (TRIUMPH program) read out across 2025–2026. FDA approval timing depends on trial outcomes and submission timelines. Check Lilly's investor communications for current status — this answer reflects April 2026 data.
The triple receptor activity drives strong GI side effects. Slow titration is essential — published trial protocols took ~28+ weeks to reach 12 mg. Faster escalation produces severe nausea and high discontinuation rates.
Sources
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Mechanism, clinical evidence, side effects, costs, and provider listings for Retatrutide therapy.
See Retatrutide guideMedical Disclaimer: This content is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare provider before beginning any peptide therapy treatment.