Medical Disclaimer

This website is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before starting, changing, or stopping any medication or supplement. Dosage information reflects published FDA-approved labeling or publicly available clinical trial data — individual treatment decisions must be made by a licensed physician.

About retatrutide

Retatrutide (LY3437943) is an investigational triple agonist targeting GIP, GLP-1, and glucagon receptors. It is not yet FDA-approved but has shown remarkable efficacy in Phase 2 clinical trials. This page summarizes publicly available clinical trial dosing information — it is not a prescription guide.

Indication

Investigational. Not FDA-approved. Clinical trial data only. Do not use this information to self-medicate.

Research / Trial Dosing Reference

Dosing data from published clinical trials. Not an approved prescription protocol.

Week / PhaseDoseAt 2.5 mg/mLAt 5 mg/mLNotes
Weeks 1–4 (trial initiation)1 mg2 units
(5 mg/mL)
1 units
(10 mg/mL)
Initiation dose in Phase 2 trial. Investigational — not approved for clinical use.
Weeks 5–8 (trial escalation)2 mg4 units
(5 mg/mL)
2 units
(10 mg/mL)
Dose escalation step in trial protocol.
Weeks 9–124 mg8 units
(5 mg/mL)
4 units
(10 mg/mL)
Low maintenance arm in Phase 2 study.
Maintenance arm (8 mg)8 mg16 units
(5 mg/mL)
8 units
(10 mg/mL)
Middle maintenance arm. Associated with ~17.5% body weight loss at 24 weeks.
Maintenance arm (12 mg)12 mg24 units
(5 mg/mL)
12 units
(10 mg/mL)
Highest trial arm. Associated with ~24% body weight loss at 48 weeks. Do not use without physician supervision.

Units shown assume a standard U-100 insulin syringe (100 units = 1 mL). Always confirm your vial concentration with your pharmacy.

Dose Calculator

Enter your prescribed dose and vial concentration to calculate how many units to draw.

mg ↔ Units Dose Calculator

Convert between milligrams and insulin-syringe units for compounded GLP-1 medications. Uses a standard U-100 syringe (100 units = 1 mL).

Units (U-100 syringe)100 units
Volume1.000 mL

2.5 mg at 2.5 mg/mL → 1.000 mL → 100 units on a U-100 (100-unit / 1 mL) insulin syringe

Always verify calculations with your prescribing provider or pharmacist before administering any medication. This calculator is for reference only.

Injection Sites

Abdomen (trial protocol)

Subcutaneous injection into abdominal fatty tissue.

  • Same technique as other GLP-1 injections
  • Rotate sites

Storage Instructions

  • Investigational product — storage handled by clinical trial site
  • If compounded: follow pharmacy instructions
  • Typically requires refrigeration

Common Side Effects

Contact your healthcare provider if side effects are severe or persistent.

  • Nausea (most common in trials)
  • Vomiting
  • Diarrhea
  • Constipation
  • Decreased appetite
  • GI side effects generally similar to other GLP-1 agonists

Frequently Asked Questions

Q

Is retatrutide FDA-approved?

No. As of mid-2026, retatrutide is still in clinical trials (Phase 2 completed, Phase 3 ongoing). It is not available as an approved prescription drug. The information on this page is from published clinical trial data only.
Q

How does retatrutide compare to tirzepatide?

Retatrutide adds glucagon receptor agonism to the dual GIP/GLP-1 mechanism of tirzepatide. Phase 2 results showed ~24% average body weight loss at 48 weeks at the 12 mg dose — higher than published tirzepatide trial results. However, direct head-to-head trial data does not yet exist.
Q

Can I get retatrutide from a compounding pharmacy?

Some compounding pharmacies have begun offering retatrutide peptide. However, this is entirely off-label and without FDA oversight for purity, potency, or sterility. Consult a physician before considering any experimental compound.
Q

When will retatrutide be available?

Based on typical Phase 3 timelines, FDA approval (if successful) could come in 2026–2027. Eli Lilly has not confirmed a specific approval timeline.

Primary Source

FDA / Clinical Source

Dosing information sourced from: https://clinicaltrials.gov/study/NCT04867785