Phase II Reference Titration Protocol
The Eli Lilly Phase II SURMOUNT trial used the following titration for the highest-dose cohort:
Phase II Maximum-Dose Ladder (12 mg endpoint)
- Weeks 1–4: 2 mg once weekly - Weeks 5–8: 4 mg once weekly - Weeks 9–16: 8 mg once weekly - Week 17+: 12 mg once weekly (maintenance)Key principle: 4 weeks minimum at each step before advancing. The glucagon component requires more adaptation time than pure GLP-1 agonists. Participants who tolerated 8 mg well for 8 weeks before moving to 12 mg had the best tolerability outcomes.
Phase II Lower-Dose Cohorts
Participants randomized to lower maintenance doses (4 mg, 8 mg) used identical titration steps but held at a lower maximum. This matters for community protocols: if 8 mg is your target, a 2 → 4 → 8 ladder with 4-week holds is still the appropriate path.Conservative Tolerability Protocol
For users with GI sensitivity history, prior nausea on Semaglutide or Tirzepatide, or lower body weight (<70 kg), a conservative protocol reduces dropout risk:
Conservative Ladder
- Weeks 1–4: 1 mg once weekly - Weeks 5–8: 2 mg once weekly - Weeks 9–12: 3 mg once weekly - Weeks 13–16: 4 mg once weekly - Weeks 17–24: 6 mg once weekly (hold if GI symptoms persist) - Weeks 25–32: 8 mg once weekly - Weeks 33+: 10–12 mg once weekly (advance only if 8 mg well tolerated)Total time to maximum dose: 8+ months. This is not slow — this is the protocol that produces sustainable long-term adherence versus the rapid titration that produces 6-week discontinuation.
Calculate your Retatrutide Titration Guide dose Vial strength, BAC water, exact syringe draw in IU. Free, no signup. Open Calc →
Tolerance Ceiling and Dose Hold Rules
Nausea Decision Tree
Mild nausea (manageable, no vomiting): Hold current dose for an additional 2 weeks. Reassess. If resolved, attempt next step.Moderate nausea (affecting daily function, 1–3 vomiting episodes/week): Do not advance. Hold current dose for 4+ additional weeks. Consider dose reduction by one step if not improving at 4 weeks.
Severe nausea/vomiting (daily vomiting, unable to maintain hydration): Reduce dose by one step immediately. Do not attempt re-escalation for 6 weeks minimum.
The 2.5 mg → 3 mg Jump: Community Pattern
A recurring pattern in community reports involves users on informal protocols who started at 2.5 mg (splitting a 5 mg vial) and jumped to 3 mg. Even this small 20% increase caused disproportionate nausea in some subjects. This reflects the glucagon receptor's steep dose-response curve at low doses. Stay within the ladder structure — do not improvise fractional steps based on vial convenience.Maximum Dose Considerations
12 mg weekly is the Phase II maximum-studied dose. Community reports of doses above 12 mg exist but have no supporting safety data. Phase II showed diminishing weight loss returns above 8 mg for many participants — the difference between 8 mg and 12 mg was meaningful in trial data but individual response varies. Many researchers find 8 mg is a sufficient endpoint without the additional GI burden of 12 mg.Injection Timing and Practical Notes
Day consistency: Inject on the same day each week within a ±2-day window. Unlike daily compounds, missing by 1–2 days does not significantly alter steady-state plasma levels (6-day half-life).
Injection day strategy: Injecting Friday evening allows the peak nausea window (24–72 hours post-injection) to fall on the weekend when activity is reduced.
Site rotation: Subcutaneous abdomen, outer thigh, or upper arm. Rotate sites each injection. Retatrutide's larger peptide molecule can cause more injection site reactions than smaller GLP-1 analogs in some users — inspect injection sites and avoid the same location for 2+ weeks.
Temperature: Allow vial to reach room temperature before drawing. Subcutaneous injection of cold solution increases injection site discomfort without any pharmacokinetic benefit.
Concentration and Draw Calculations
Retatrutide vials from compounding pharmacies typically come in 2 mg/mL, 4 mg/mL, or 8 mg/mL concentrations. The same dose in milligrams requires different draw volumes depending on concentration.
See the Vial Concentration Math guide for the core formula and worked examples. Use the ASCEND Retatrutide Calculator to get the exact syringe draw for your specific vial.
Quick Reference: 2 mg Dose Draw by Concentration
- 2 mg/mL vial: draw 1.0 mL (100 units on 100-unit syringe) - 4 mg/mL vial: draw 0.5 mL (50 units) - 8 mg/mL vial: draw 0.25 mL (25 units)Quick Reference: 4 mg Dose Draw by Concentration
- 2 mg/mL vial: draw 2.0 mL — exceeds standard syringe capacity; use 3 mL syringe - 4 mg/mL vial: draw 1.0 mL (100 units) - 8 mg/mL vial: draw 0.5 mL (50 units)References
- [1]Jastreboff AM, et al. "Triple-Hormone-Receptor Agonist Retatrutide for Obesity." N Engl J Med. 2023;389(6):514-526.
- [2]Eli Lilly TRIUMPH Phase III Protocol. ClinicalTrials.gov NCT05725629.