Retatrutide (5mg)
Retatrutide is a novel triple agonist targeting the GLP-1, GIP, and glucagon receptors, studied for significant weight loss and metabolic improvement in obesity and type 2 diabetes. With an extended half-life of approximately 6 days, it allows for convenient weekly subcutaneous administration with a gradual titration protocol.
Reviewed by the AllPeptides.eu Editorial Team·Last reviewed: 2026-06-16
Educational information. Not medical advice, and no efficacy claim is implied. Regulatory approval is not a use recommendation by AllPeptides.eu.
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Research monograph
See the full Retatrutide encyclopedia page with mechanism, evidence tier, related variants and research context.
How It Works
Retatrutide is the first triple agonist that simultaneously activates three key metabolic hormone receptors: GLP-1, GIP, and glucagon. This triple mechanism produces synergistic effects on appetite suppression, energy expenditure, and glucose metabolism. The GLP-1 component reduces appetite and slows gastric emptying; GIP enhances insulin secretion and supports fat metabolism; glucagon receptor activation increases energy expenditure and promotes fat oxidation. In clinical trials, participants receiving 12 mg weekly lost an average of 24% of their body weight in 48 weeks.
Quick Start
- Reconstitution: Add 1.0 mL bacteriostatic water → 5.0 mg/mL concentration.
- Typical weekly range: 2–8 mg once weekly (gradual ramp-up over 12+ weeks).
- Storage: Lyophilized: freezer at −20 °C; after reconstitution, refrigerator at 2–8 °C; use within 4 weeks.
Standard / Gradual Titration (1 mL = 5.0 mg/mL)
Route: Subcutaneously | Frequency: Once weekly
| Week | Dose | Units (per injection) |
|---|---|---|
| Weeks 1–4 | 2 mg (2,000 mcg) | 40 Units (0.40 mL) |
| Weeks 5–8 | 4 mg (4,000 mcg) | 80 Units (0.80 mL) |
| Weeks 9–12 | 6 mg (6,000 mcg) | 2 × 60 Units (0.60 mL) — 2 vials |
| Weeks 13+ | 8 mg (8,000 mcg) | 2 × 80 Units (0.80 mL) — 2 vials |
Studies report administration once weekly subcutaneously. For doses >5 mg, reconstitute multiple vials (each with 1.0 mL) and draw up the required volume. Volumes >1.0 mL are split into 2 separate subcutaneous injections at different sites. Dose increases every 4 weeks.
Related compounds
Reconstitution Steps
- Draw 1.0 mL bacteriostatic water with a sterile syringe.
- Slowly inject down the side of the vial; avoid foaming.
- Gently swirl/roll until dissolved (do not shake vigorously).
- Note reconstitution date and refrigerate at 2–8 °C, protecting from light.
- Use within 4 weeks of reconstitution.
Protocol Overview
- Goal: Achieve significant weight loss (up to 24%) and improve metabolic parameters via triple receptor agonism.
- Schedule: Weekly subcutaneous injections for 12–48 weeks with gradual dose escalation.
- Storage: Lyophilized frozen at −20 °C; reconstituted refrigerated at 2–8 °C; use within 4 weeks.
Dosing Protocol
- Start: 2 mg once weekly for the first 4 weeks.
- Escalation: Increase to 4 mg (Wks. 5–8), then 6 mg (Wks. 9–12).
- Maintenance: 8 mg weekly (Wks. 13+) — Standard protocol. Aggressive: 12 mg/wk.
- Frequency: Once weekly (subcutaneous); consistent day/time.
- Cycle Duration: Minimum 12 weeks of titration; clinical trials extended to 48 weeks.
- Break between cycles: After cycle completion, a 6–8 week pause is recommended. Retatrutide (a triple GIP/GLP-1/Glucagon agonist) has a prolonged action — a longer washout period is required.
Washout & Cycle Restart
When can I restart?
After cycle completion, a 6–8 week pause is recommended. Retatrutide (a triple GIP/GLP-1/Glucagon agonist) has a prolonged action — a longer washout period is required.
Minimum wait period: 6 weeks
Storage Instructions
- Lyophilized: Store at or below −20 °C; protect from moisture and light.
- Reconstituted: Refrigerate at 2–8 °C immediately after mixing; use within 4 weeks.
- Handling: Allow frozen vials to reach room temperature before opening.
- Avoid repeated freeze-thaw cycles.
Important Notes
- Weekly Consistency: Choose a specific day/time and adhere to it throughout the protocol.
- Gradual Titration is Essential: Starting at 2 mg (vs. higher doses) significantly reduces initial GI side effects.
- For doses >5 mg (>1.0 mL), split into multiple injections at different sites.
- Monitor for gastrointestinal side effects (nausea, diarrhea); if severe, extend time at the current dose.
Potential Benefits & Side Effects
Potential Benefits:
- Significant weight loss: Up to 24% body weight reduction in 48 weeks at 12 mg weekly.
- Glycemic improvement: Significant reductions in HbA1c (~2.0%) in adults with T2D.
- Metabolic benefits: Improvements in lipid profiles, blood pressure, and cardiovascular risk markers.
- Convenient dosing: Weekly subcutaneous administration.
Potential Side Effects:
- Gastrointestinal effects: Nausea, diarrhea, vomiting, and constipation — typically mild to moderate and decreasing over time.
- Starting at 2 mg (vs. 4 mg) significantly reduces initial GI side effects.
- Injection site reactions: Mild redness, swelling, or discomfort.
- Overall safety profile: Meta-analysis found no significant increase in overall adverse events vs. placebo.
⚠️ Serious Warnings & Long-Term Risks
The following warnings are based on published literature, FDA labels, and post-marketing surveillance. They do not constitute medical advice. Consult a healthcare professional.
Potential thyroid C-cell risk
As a triple GLP-1/GIP/Glucagon agonist, the same class-effect warning as semaglutide/tirzepatide is expected.
📄 Phase 2 Trial — NEJM 2023References
- New England Journal of Medicine (2023) — Triple-Hormone-Receptor Agonist Retatrutide for Obesity — Phase 2, 48 weeks
View Source - JAMA Network (2023) — Retatrutide Phase 2: 24% weight loss at 12 mg weekly
View Source - The Lancet (2023) — Retatrutide in T2D: Phase 2 (weight loss and glycemic outcomes)
View Source - Metabolites (PMC, 2025) — Retatrutide — A Game Changer in obesity pharmacotherapy
View Source - Baylor University (PMC, 2025) — Meta-analysis of efficacy and safety of retatrutide (878 participants)
View Source - Nature Reviews Endocrinology (2024) — Triple agonists for obesity and diabetes: clinical overview
View Source
Recommended Supplements
Vitamin B12 (Methylcobalamin)
Vitamin D3 + K2
Omega-3 Fish Oil (EPA/DHA)
Protein / Collagen
Fiber Supplement (Psyllium)
External Sources & Regulatory Status
Regulatory Approvals
Obesity / Type 2 diabetes
Obesity / Type 2 diabetes
Phase III clinical trials
Educational information. Not medical advice, and no efficacy claim is implied. Regulatory approval is not a use recommendation by AllPeptides.eu.
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