The TRIUMPH Trial Dosing Protocol
The retatrutide dosing schedule used in Eli Lilly’s Phase 3 TRIUMPH trials is the only validated protocol backed by clinical data. It starts at 2 mg once weekly for four weeks. The dose increases to 4 mg once weekly for the next four weeks. From there, escalation proceeds every four weeks: 4 mg to 6 mg to 9 mg, and finally to the target maintenance dose of 12 mg once weekly. This gradual titration is designed to minimize gastrointestinal side effects by giving the body time to adapt to each dose level.
The 12 mg maintenance dose produced 28.3% average weight loss at 80 weeks in the TRIUMPH-1 trial. A lower 8 mg maintenance dose was also studied and produced weight loss of approximately 22-24%, though detailed results for the lower dose have not been published as of May 2026. The 4 mg dose produced approximately 15-17% weight loss in Phase 2, comparable to semaglutide at 2.4 mg weekly.
Research Peptide Dosing Considerations
Retatrutide sold on the grey market as a research peptide is typically supplied as lyophilized powder in 5 mg, 10 mg, or 20 mg vials. The powder must be reconstituted with bacteriostatic water before injection. A standard reconstitution uses 2 mL of bacteriostatic water per 10 mg vial, yielding a concentration of 5 mg/mL. The dose is then drawn into an insulin syringe measured in units, where each unit on a 100-unit insulin syringe equals 0.01 mL.
Common dosing for research purposes follows the TRIUMPH schedule: 2 mg weekly for 4 weeks, then 4 mg weekly. Many grey market users escalate more aggressively or start at higher doses, but the trial data clearly shows that faster escalation increases the risk of nausea, vomiting, and discontinuation. The TRIUMPH protocol’s 4-week intervals between dose increases are not arbitrary — they were determined through dose-finding studies in Phase 1 and 2.
Reconstitution Instructions
To reconstitute a 10 mg vial of retatrutide, draw 2 mL of bacteriostatic water into a syringe, inject it slowly down the side of the vial (not directly onto the powder), and swirl gently until the powder dissolves completely. Do not shake the vial — shaking can denature the peptide. The resulting solution contains 5 mg of retatrutide per mL. A 2 mg dose would be 0.4 mL, or 40 units on a 100-unit insulin syringe.
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