Reconstitute: Add 2.0 mL bacteriostatic water → 10.0 mg/mL concentration for optimal weekly doses.
Typical weekly range: 2–12 mg once weekly (gradual escalation over 12+ weeks).
Easy measuring: At 10.0 mg/mL, 1 unit = 0.01 mL ≈ 100 mcg on a U-100 insulin syringe.
Storage: Lyophilized: freeze at −20 °C (−4 °F); after reconstitution, refrigerate at 2–8 °C (35.6–46.4 °F) and use within 2–4 weeks.
Dosing & Reconstitution Guide
Educational guide for reconstitution and weekly dosing
Standard / Gradual Titration Approach (2 mL = 10.0 mg/mL)
Frequency: Inject once weekly subcutaneously. This schedule follows clinical trial protocols that demonstrated significant weight loss (up to 24% at 48 weeks with 12 mg weekly) while minimizing gastrointestinal adverse events through gradual escalation. Starting at 2 mg weekly (versus 4 mg) significantly reduces initial GI side effects. The 20 mg vial size with 2.0 mL reconstitution provides excellent concentration (10.0 mg/mL) for convenient measuring. For the maintenance dose (12 mg = 1.20 mL), either split into two 0.60 mL injections at different sites or reconstitute an additional vial.
Reconstitution Steps
Draw 2.0 mL bacteriostatic water with a sterile syringe.
Inject slowly down the vial wall; avoid foaming.
Gently swirl/roll until dissolved (do not shake vigorously).
Label with reconstitution date and refrigerate at 2–8 °C (35.6–46.4 °F), protected from light.
Note: The 20 mg vial size is highly efficient for weekly protocols. Lower doses (2–8 mg) fit comfortably in a single syringe, while the maintenance dose (12 mg) requires either splitting across two injection sites or using a second vial for the remaining 0.20 mL (2 mg).
Important: This guide is for educational purposes only and is not medical advice. For research use only. Not for human consumption.
Supplies Needed
Plan based on a 12–48 week weekly protocol with gradual titration to maintenance dose.
Retatrutide 20mg: Highly efficient vial size for weekly protocols
12 weeks (2→4→8 mg titration): 3 vials
24 weeks (up to 12 mg): 10 vials
48 weeks (maintenance at 12 mg): 25 vials
Per week: 1 syringe (once-weekly dosing)
12 weeks: 12 syringes
24 weeks: 24 syringes
48 weeks: 48 syringes
Bacteriostatic Water: Use 2.0 mL per vial for reconstitution.
12 weeks (3 vials): 6 mL
24 weeks (10 vials): 20 mL
48 weeks (25 vials): 50 mL
Alcohol Pads: One for the vial stopper + one for the injection site each week.
Per week: 2 swabs
12 weeks: 24 swabs
24 weeks: 48 swabs
48 weeks: 96 swabs
Protocol Overview
Concise summary of the once-weekly regimen based on clinical trial protocols.
Goal: Achieve substantial weight loss (up to 24% of body weight) and improved metabolic parameters through triple receptor agonism.
Schedule: Weekly subcutaneous injections for 12+ weeks with gradual dose escalation.
Dose Range: 2–12 mg once weekly; clinical trials tested up to 12 mg as the maximum maintenance dose.
Reconstitution: 2.0 mL per 20 mg vial (10.0 mg/mL) provides optimal concentration for weekly dosing with minimal waste.
Storage: Lyophilized frozen at −20 °C (−4 °F); reconstituted solution refrigerated at 2–8 °C (35.6–46.4 °F); use within 2–4 weeks.
Dosing Protocol
Evidence-based weekly titration approach from clinical trials.
Start: 2 mg once weekly for first 4 weeks to establish tolerability.
Escalation: Increase to 4 mg weekly (Weeks 5–8), then 8 mg weekly (Weeks 9–12).
Maintenance: 12 mg weekly (Week 13 onward) for maximum efficacy; 8 mg weekly is an alternative maintenance dose.
Frequency: Once per week (subcutaneous); consistent day/time recommended.
Cycle Length: Minimum 12 weeks for titration; clinical trials extended to 48 weeks showing sustained weight loss.
Timing: Any consistent weekly schedule; rotate injection sites each week.
Storage Instructions
Proper storage maintains peptide stability and potency.
Lyophilized: Store at −20 °C (−4 °F) or colder for long-term preservation; protect from moisture and light.
Reconstituted: Refrigerate at 2–8 °C (35.6–46.4 °F) immediately after mixing; use within 2–4 weeks for maximum potency.
Handling: Allow frozen vials to reach room temperature before opening to minimize condensation; never expose reconstituted solution to heat or direct sunlight.
Aliquoting: For extended storage beyond 4 weeks, consider freezing unused aliquots; avoid repeated freeze-thaw cycles.
Important Notes
Practical considerations for safe and effective weekly administration.
Weekly consistency: Choose a specific day/time for your weekly injection and maintain this schedule throughout the protocol.
Gradual titration is essential: Starting at 2 mg weekly (versus higher doses) significantly reduces initial gastrointestinal side effects.
Efficient vial size: The 20 mg vial provides excellent value, requiring only 3 vials for the first 12 weeks of titration.
Use new sterile insulin syringes for each injection; dispose immediately in a puncture-proof sharps container.
Rotate injection sites weekly (abdomen, thighs, upper arms) at least 1 inch apart to prevent local irritation or lipohypertrophy.
For the 12 mg maintenance dose (1.20 mL), either split into two 0.60 mL injections at different sites or use a second vial for the remaining volume.
Monitor for gastrointestinal side effects (nausea, diarrhea); if severe, consider extending the time at current dose before escalating.
How This Works
Retatrutide is a first-in-class triple agonist that simultaneously activates three key metabolic hormone receptors: GLP-1 (glucagon-like peptide-1), GIP (glucose-dependent insulinotropic polypeptide), and glucagon. This triple mechanism produces synergistic effects on appetite suppression, energy expenditure, and glucose metabolism that exceed single or dual agonists.
The GLP-1 component reduces appetite and slows gastric emptying; GIP enhances insulin secretion and may support fat metabolism; glucagon receptor activation increases energy expenditure and promotes fat oxidation. With an extended half-life of approximately 6 days, retatrutide enables convenient once-weekly dosing while maintaining therapeutic levels.
In clinical trials, participants receiving 12 mg weekly retatrutide lost an average of 24% of their body weight over 48 weeks. In adults with type 2 diabetes, retatrutide (up to 12 mg weekly) achieved approximately 17% weight loss at 36 weeks alongside HbA1c reductions of approximately 2.0% compared to placebo. A 2025 meta-analysis of three trials (878 participants) confirmed retatrutide achieved significantly greater weight reduction than placebo (mean difference approximately 14% of body weight) with no significant increase in overall adverse events.
Potential Benefits & Side Effects
Observations from phase 2 and phase 3 clinical trials in humans.
Potential Benefits
Substantial weight loss: Up to 24% reduction in body weight at 48 weeks with 12 mg weekly dosing.
Glycemic improvement: Significant HbA1c reductions (approximately 2.0%) in adults with type 2 diabetes.
Metabolic benefits: Improvements in lipid profiles, blood pressure, and cardiovascular risk markers.
Convenient dosing: Once-weekly subcutaneous administration improves adherence compared to daily regimens.
Common Side Effects
Gastrointestinal effects: Nausea, diarrhea, vomiting, and constipation are the most common adverse events; typically mild-to-moderate and diminish over time.
Starting at 2 mg weekly (versus 4 mg) significantly reduces initial GI adverse events.
Injection site reactions: Mild redness, swelling, or discomfort at injection sites may occur; rotate sites to minimize.
Overall safety profile: Meta-analysis found no significant increase in overall adverse events compared to placebo.
Lifestyle Factors
Complementary strategies to optimize outcomes during retatrutide protocols.
Nutrition: Adopt a balanced, protein-forward diet (1.0–1.2 g/kg body weight) to preserve lean mass during weight loss.
Hydration: Maintain adequate fluid intake, especially during dose titration when GI effects are most common.
Physical activity: Combine resistance training (2–3×/week) with moderate aerobic exercise to support metabolic adaptations and preserve muscle mass.
Sleep & stress: Prioritize 7–9 hours of quality sleep and implement stress management techniques to support hormonal balance and adherence.
Meal timing: Some individuals find smaller, more frequent meals help manage GI side effects during initial titration.
Injection Technique
Subcutaneous injection guidelines based on clinical best practices and CDC recommendations.
Pre-Injection Preparation
Wash hands thoroughly with soap and water.
Clean the vial stopper with an alcohol swab and allow to air dry.
Select injection site (abdomen, thigh, or upper arm) and clean with a fresh alcohol swab; allow to dry completely.
Draw prescribed dose carefully; check for air bubbles and expel if present.
Injection Procedure
Pinch a skinfold of approximately 1 inch between thumb and forefinger.
Insert needle at a 90-degree angle (45-degree if subcutaneous fat layer is thin) into the pinched skin.
Do not aspirate for subcutaneous injections (aspiration is not required and may increase discomfort).
Inject slowly and steadily; depress plunger completely.
Withdraw needle straight out and apply gentle pressure with clean gauze if needed.
Post-Injection Care
Dispose of used syringe immediately in a puncture-proof sharps container; never recap needles.
Return reconstituted vial to refrigerator promptly.
Rotate injection sites weekly (at least 1 inch apart) to prevent lipohypertrophy.
Monitor for excessive redness, swelling, or signs of infection at injection site.