Updated March 2026 · Based on TRIUMPH Phase 2 Data
Retatrutide Dosing Protocol & Titration Guide
A complete reference for the retatrutide titration schedule used in the TRIUMPH clinical trials — including reconstitution, injection technique, and side effect management.
⚠ Research Use Only: Retatrutide is not FDA-approved. The dosing information on this page reflects the protocol used in Eli Lilly's TRIUMPH Phase 2 trial. It is provided for educational reference only and does not constitute medical advice. Do not self-administer investigational compounds without physician supervision.
Drug Class
GLP-1 / GIP / Glucagon Triple Agonist
Compound
LY3437943
Route
Subcutaneous Injection
Frequency
Once Weekly
Max Trial Dose
12 mg / week
Titration Schedule
The TRIUMPH Phase 2 trial used a slow, 4-week titration at each dose level. This gradual approach minimizes gastrointestinal side effects — the primary reason for discontinuation in GLP-1 class drugs. Slower titration than shown below is often used in clinical practice to further improve tolerability.
Weeks
Dose
Notes
1–4
2 mg
Starting dose. GI adaptation period. Expect mild nausea and reduced appetite. Establish injection routine.
5–8
4 mg
First up-titration. Monitor for nausea and vomiting. Eat smaller, lower-fat meals. Stay well hydrated.
9–12
8 mg
Significant appetite suppression expected. Ensure adequate protein and caloric intake. Monitor resting heart rate.
13–16
12 mg
Maximum trial dose. Strongest weight loss effect observed. Monitor for tachycardia. Do not exceed.
17+
Maintenance
Hold at highest tolerated dose indefinitely. If GI side effects persist, consider stepping back one dose level.
* Titration schedule from the TRIUMPH Phase 2 trial as published in The New England Journal of Medicine, 2023. Individual tolerance varies.
💡 Tolerability tip: Many researchers opt for a slower titration — holding each dose for 6–8 weeks rather than 4 — particularly at the 4mg and 8mg steps. This is not standard protocol but is widely reported to reduce GI side effects without meaningfully impacting long-term outcomes.
Reconstitution & Injection Guide
Reconstitution Steps
1
Use bacteriostatic water (BAC water)Contains 0.9% benzyl alcohol. Prevents bacterial growth after reconstitution. Do not use sterile water or saline.
2
Calculate your dilution ratioCommon: 1 mL BAC water per vial = 1mg per 0.1mL. Adjust based on your vial size and target draw volume.
3
Inject water slowly down the vial wallDo not aim directly at the powder. Do not shake — gently swirl until fully dissolved. Solution should be clear.
4
Store correctlyReconstituted: refrigerate 2–8°C, use within 28–30 days. Lyophilized powder: room temp short-term, freeze long-term.
5
Use U-100 insulin syringesCalculate draw volume from your dilution ratio. Draw slowly and tap out air bubbles before injecting.
Injection Sites
Preferred
Abdomen — inject at least 2 inches from the navel. Pinch the skin slightly. Rotate quadrants each week.
Good
Outer upper thigh — rotate left and right thigh each week. Easy for self-injection.
Alt
Posterior upper arm (tricep area) — may require a mirror or assistance for self-injection.
Avoid
Scar tissue, bruised skin, within 2 inches of navel, waistband or beltline area, same site as previous injection.
Needle angle: 45° for lean individuals, 90° for those with more subcutaneous tissue. Always inject into fat layer, not muscle.
Phase 2 Mean Body Weight Reduction at 24 Weeks (NEJM 2023)
−8.7%Placebo
−17.3%4 mg dose
−22.8%8 mg dose
−24.2%12 mg dose
Side Effects & Management
Gastrointestinal side effects are the most common adverse events, consistent with the GLP-1 class. Most occur early in treatment and decrease over time. The table below reflects rates reported at the 12mg dose in the Phase 2 trial.
Side Effect
Frequency
Typical Onset
Management
Nausea
~42%
Weeks 1–8
Eat small, low-fat meals; avoid eating right before injection; slow titration if severe
Vomiting
~25%
Weeks 1–8
Stay hydrated; consider anti-emetics; do not skip doses; slow titration if persistent
Diarrhea
~18%
Variable
BRAT diet; hydration; usually self-resolving within a few weeks
Constipation
~12%
Variable
Increase dietary fiber and water intake; consider fiber supplement
Expected mechanism — ensure adequate protein (>100g/day). Do not restrict intake severely.
Injection site reactions
<5%
Any time
Rotate injection sites every week; allow vial to reach room temperature before injecting
Key Considerations
Inject on the same day each week — consistency improves tolerability and compliance
Do not inject into muscle — retatrutide is a subcutaneous peptide
Maintain adequate protein intake (≥100g/day) to preserve lean muscle mass during weight loss
Monitor resting heart rate periodically — glucagon receptor agonism can cause mild tachycardia
Reconstituted peptide should be clear and colorless — discard if cloudy or particulate
Do not freeze reconstituted peptide — freeze only unreconstituted lyophilized powder
Do not exceed 12mg/week — this was the maximum dose used in trials
Do not combine with other GLP-1 agonists (semaglutide, tirzepatide, liraglutide)
Do not use if personal or family history of medullary thyroid carcinoma or MEN2
Printable Reference
The dosing protocol above is available as a free one-page printable PDF — formatted for easy printing, sharing in research communities, and reference during reconstitution.
Disclaimer: This page is for educational and research reference purposes only. Retatrutide is an investigational drug not approved by the FDA. Research peptides are labeled for laboratory use only and are not intended for human consumption. Nothing on this site constitutes medical advice. Always consult a licensed physician before making any healthcare decisions. Not affiliated with Eli Lilly and Company. This page may contain affiliate links.