Triple agonist (GIP/GLP-1/glucagon). Phase 3 trials show greater weight loss than tirzepatide; not yet approved.
This compound sits in research-grey territory. The caveats below carry more weight than for FDA-approved entries — read them.
Eli Lilly's triple-agonist of GIPR/GLP-1R/GCGR. Phase 2 (NEJM 2023) showed up to 24% weight reduction at 48 weeks — exceeding tirzepatide. Phase 3 TRIUMPH trials underway. Glucagon-receptor activation distinguishes mechanism — risks and benefits distinct from semaglutide/tirzepatide.
Not yet FDA-approved. Any product sold as 'retatrutide' before approval is research-grade at best, counterfeit at worst. Glucagon agonism creates a different metabolic profile than tirzepatide.
Aib at position 2; fatty acid acylation. Triple agonist sequence engineered for GIP/GLP-1/glucagon receptor activity.
Known risk or pharmacological conflict.
Stack doesn't rank peptides — we surface the diversity of opinion. Each card paraphrases a public-record stance from a named source. Where they conflict is where you should slow down and read both.
Phase 2 TRIUMPH-1 (NEJM 2023) showed ~24% body-weight reduction at 48 weeks at maximum dose — larger than any other approved or pending obesity drug. Triple agonism at GLP-1 + GIP + glucagon receptors. Phase 3 ongoing with FDA approval expected late 2026 / early 2027.
Source →S-tier — top of his peptide ranking. "GLP-3 — three receptors, suppresses appetite AND accelerates metabolism. I've been taking Reta for about a year. Reduces food noise without hunger suppression to the point of nausea." Has used personally for 12+ months.
Pre-FDA-approval, Retatrutide use by patients is research-grey only. Several telehealth platforms paused compounded-Reta access after Eli Lilly's April 2025 lawsuits against compounders. Until FDA approval lands, all Retatrutide access carries quality + legal exposure that exceeds Tirzepatide-era compounding.
Per-claim grading. Each claim is graded independently — same peptide, different claims can carry different grades.
External links to PubMed searches, ClinicalTrials.gov, and FDA materials. We do not host papers — we point at canonical sources.
Pre-filled with this compound's published dose range: 1-12 mg · weekly, subcutaneous
Draw volume exceeds 100 units (1 mL). Either reduce dose or split into multiple injections.
Calculator is a discussion tool. Verify reconstitution + dosing with a qualified provider. Stack is not a prescription source. Use sterile technique and inspect every vial.
How much a first cycle actually costs across the channels people use. Pick the protocol length you're considering — Stack multiplies the monthly band by cycle weeks. Same caveats apply: ranges are facts, quality varies, this is not legal advice.
Numbers reflect publicly-advertised price ranges, not vendor quotes. Insurance, prescription costs, and shipping aren't included. Channels marked unavailable are filtered out.
See pharmacies for this compound →Approximate monthly cost across the channels users actually consider — brand FDA-approved retail, US 503A compounding, Mexican pharmacies, MX farmacias magistrales, and the research-grey market. Stack lists ranges, not vendor names. Quality varies wildly across channels — see each band's note.
Not yet FDA-approved (Phase 3 trials ongoing as of April 2026).
As of 2026-04Research-grey only — no legitimate pharmacy access until FDA approval. Premium over Tirzepatide grey market reflects newer-compound scarcity.
As of 2026-04Investigational — Eli Lilly Phase 3, expected FDA filing 2026