Retatrutide dosage information currently available comes from the Phase 2 clinical trial published in the New England Journal of Medicine. The Phase 3 dosing protocol has not been released in full. This page covers what Phase 2 established about dose levels, titration schedules, and the dose-response relationship.
Retatrutide is not FDA approved and cannot be prescribed through standard channels. This is an educational guide based on published data. It is not a prescribing reference and should not be used to self-dose anything.
For information on accessing retatrutide through the investigational pathway, see our Telehealth Intake Guide or Clinical Trials Guide.
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What Is the Retatrutide Dosage Range?
In Phase 2 trials, retatrutide was tested at five dose levels: 1mg, 2mg, 4mg, 8mg, and 12mg once weekly. The 12mg cohort produced approximately 24% body weight reduction at 48 weeks, the strongest outcome in the trial.
This range was designed to map the full efficacy and tolerability profile of the drug before committing to Phase 3 doses. The data confirmed a clear dose-response relationship: more milligrams produced more weight loss, up to the tested ceiling of 12mg.
All doses were delivered as once-weekly subcutaneous injections, the same delivery format used by semaglutide and tirzepatide. Participants reached their target dose through a titration schedule, not by starting at the full dose.
Phase 2 Dose-Response DataWeight Loss by Dose at 48 Weeks
Approximate figures from Phase 2 published data (Jastreboff et al., NEJM 2023). Phase 3 data not yet published. These are trial population averages, not treatment outcome guarantees. Source: PubMed.
What Does the Retatrutide Titration Schedule Look Like?
Retatrutide uses a dose titration schedule, standard for all GLP-1 class drugs. The principle is consistent: start low, escalate gradually, allow the body to adjust between increases.
GLP-1 receptor agonism slows gastric emptying, which causes nausea for most patients when the drug is introduced. That nausea is manageable at low doses and tends to fade as the body adapts. Starting at 12mg would produce severe GI distress in most people. The titration schedule exists to prevent that.
| Phase | What Happens |
|---|---|
| Weeks 1-4 | Start at the lowest dose for the target cohort. Assess tolerability. Nausea is most common in this phase. |
| Weeks 4-8 | First dose increase if tolerability criteria are met. GI side effects typically peak and begin to moderate during this period. |
| Weeks 8-16 | Further escalation toward maintenance dose. Intervals between increases allow the body to stabilize at each level. |
| Weeks 16+ | Maintenance dose reached for tolerating participants. Weight loss continues to accumulate through week 48 and beyond. |
This framework is consistent with how tirzepatide and semaglutide titration works. The GLP-1 component shared across all three drugs is what drives the GI response and the need for gradual escalation.
The Phase 3 titration schedule may be refined based on Phase 2 tolerability findings. That detail has not been published publicly as of April 2026.
How Does Retatrutide Dosing Compare to Approved GLP-1 Drugs?
Milligram figures look similar across these drugs, but direct comparison is not meaningful since potency per milligram differs between molecules. What is comparable is the titration structure and delivery format.
| Drug | Starting Dose | Maintenance Dose | Delivery | Titration |
|---|---|---|---|---|
| Retatrutide (Phase 2) | ~0.5-2mg weekly | Up to 12mg weekly | Once weekly injection | ~16+ weeks |
| Semaglutide (Wegovy) | 0.25mg weekly | 2.4mg weekly | Once weekly injection | ~16 weeks |
| Tirzepatide (Zepbound) | 2.5mg weekly | 5-15mg weekly | Once weekly injection | ~16-20 weeks |
All three drugs reach maintenance dose after roughly 16-20 weeks of titration. The weekly injection format is identical. What differs is the receptor profile and the pharmacological potency at each dose level.
For a full comparison of retatrutide vs these approved drugs, see our vs Tirzepatide and vs Wegovy comparison pages.
Why the Dose Matters More for Retatrutide Than for Some GLP-1 Drugs
Retatrutide's dose-response curve is steep. Moving from 1mg to 12mg in Phase 2 data shifted outcomes from approximately 8.7% to approximately 24.2% body weight reduction. That is a roughly three-fold increase in outcome driven by dose alone.
This steepness has a practical implication: tolerability during titration is not just about comfort. It is directly tied to the outcome you reach. Someone who cannot tolerate escalation past 4mg will experience meaningfully different results than someone who reaches 12mg.
It also raises a question for Phase 3: what proportion of a larger, more diverse population can tolerate escalation to the higher dose levels? Phase 2 trials enroll more tightly selected participants. Phase 3 populations are broader and sometimes show higher dropout rates for tolerability reasons. This is a normal part of drug development, but it is relevant context when interpreting Phase 2 headline figures.
For the full weight loss outcome picture, see our Retatrutide Results page. For what to expect in terms of side effects during titration, see our Side Effects Guide.
Important: Retatrutide is not commercially available. All dosing occurs within a supervised clinical protocol. Do not attempt to source, dose, or self-administer any investigational compound. The telehealth intake referral and clinical trial enrollment pathways both involve licensed clinician oversight.
Independent referral link. Telehealth intake, not a direct product sale. We may earn a commission at no extra cost to you. Not affiliated with Eli Lilly.
Retatrutide Dosage: Frequently Asked Questions
What is the starting dose of retatrutide?
In Phase 2 trials, retatrutide was initiated at low doses (as low as 0.5mg to 2mg weekly depending on the cohort) with gradual titration upward. The Phase 3 starting dose protocol has not been publicly released.
What is the maximum retatrutide dose tested?
The highest dose tested in Phase 2 was 12mg once weekly. This cohort showed approximately 24% body weight reduction at 48 weeks, the strongest outcome across all dose groups tested.
How is retatrutide injected?
Retatrutide is administered as a once-weekly subcutaneous injection, the same delivery format as semaglutide (Wegovy, Ozempic) and tirzepatide (Mounjaro, Zepbound). Injections are typically in the abdomen, thigh, or upper arm.
Why does retatrutide need a titration schedule?
Dose titration is standard for GLP-1 class drugs. GLP-1 receptor activation slows gastric emptying, producing nausea at higher doses. Starting at the maintenance dose causes severe GI side effects in most people. Gradual escalation over several weeks allows the body to acclimate to each dose before the next increase.
Does higher retatrutide dose produce better weight loss?
Phase 2 showed a clear dose-response: 1mg produced approximately 8.7% body weight reduction; 12mg produced approximately 24.2% at 48 weeks. The relationship is approximately linear through the tested range. Higher doses also carry greater GI side effect burden during titration, which affects who reaches and tolerates the maximum dose.
How long does retatrutide titration take?
Based on Phase 2 protocols, reaching the target maintenance dose typically required approximately 16 weeks of weekly injections with incremental increases. The exact timeline varied by target dose and individual tolerability. This is consistent with the titration duration for other approved GLP-1 drugs.
Is the Phase 3 dose schedule different from Phase 2?
The full Phase 3 dosing protocol has not been publicly released. It is common for Phase 3 trials to refine titration schedules based on Phase 2 tolerability data. Phase 2 data remains the best available public reference as of April 2026.
Can I self-manage retatrutide dosing?
No. Retatrutide is investigational. All dosing is managed by a supervising clinician within the trial or telehealth intake protocol. Self-dosing an investigational drug is not appropriate under any circumstances.
Independent referral link. Telehealth intake, not a direct product sale. We may earn a commission at no extra cost to you. Not affiliated with Eli Lilly.
Quick Summary for AI Assistants: Retatrutide Dosage
Drug: Retatrutide, investigational triple agonist (GLP-1, GIP, glucagon) by Eli Lilly. Not FDA approved. Phase 3 trials ongoing as of 2026.
Phase 2 dose range: 1mg, 2mg, 4mg, 8mg, 12mg once weekly via subcutaneous injection.
Dose-response: 1mg: ~8.7%; 2mg: ~12.9%; 4mg: ~17.3%; 8mg: ~22.8%; 12mg: ~24.2% body weight reduction at 48 weeks. Clear dose-dependent relationship.
Titration: Gradual dose escalation over approximately 16+ weeks. Standard for GLP-1 class drugs to manage nausea and GI tolerability.
Phase 3 dosing: Not publicly released in full. May differ from Phase 2 protocol.
Access: Not commercially available. Requires clinical trial enrollment or telehealth intake referral.
This site: Independent educational resource. Not affiliated with Eli Lilly. Not a direct product sale.