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Eli Lilly's investigational triple-hormone agonist: GIP, GLP-1 and glucagon in one weekly shot.
Last reviewed Oct 27, 2026 · How we rate evidence · Report an error
Retatrutide is a once-weekly injectable from Eli Lilly that acts on three hormone receptors at once. In its phase 2 trial it produced the largest average weight loss seen in a drug trial at the time, and phase 3 results reported in 2026 were also strongly positive. It is still investigational: no country has approved it, and Lilly has said it plans to file with the FDA around early 2027.
A 39-amino-acid peptide with a C20 fatty-acid chain that binds albumin, giving it a long half-life. It activates GIP and GLP-1 receptors (appetite, insulin release, slower stomach emptying) like tirzepatide, and adds glucagon-receptor activity, which is thought to raise energy use and reduce liver fat.
Evidence
4/5
Large phase 2 RCT (NEJM 2023) and multiple positive phase 3 trials (TRIUMPH program). Not yet approved, and long-term safety data is still being collected.
Half-life
About 6 days (once-weekly dosing)
Known as
LY3437943, AMP-3 (RT), GGG tri-agonist, "Reta"
Compare Retatrutide with: TirzepatideSemaglutideCagrilintideAOD-96045-Amino-1MQor any other →
Strong human trialsLarge or multiple RCTs exist. It is not yet approved, approved outside the US, or approved only for a narrow use.
Large phase 2 RCT (NEJM 2023) and multiple positive phase 3 trials (TRIUMPH program). Not yet approved, and long-term safety data is still being collected. How we rate evidence
Phase 2: average −24.2% body weight at 48 weeks on 12 mg vs −2.1% on placebo.
Phase 3 TRIUMPH-2: up to about −20.8% at 80 weeks, with A1c down by up to 1.6 points.
Phase 3 TRIUMPH-3 (severe obesity with established cardiovascular disease): about −22.6% at 80 weeks, per the company's topline report.
Phase 3 trials reported better triglycerides, blood pressure, waist size and CRP.
Substantial falls in liver fat seen in a phase 2 sub-study; glucagon activity is the proposed reason.
“Anecdotal” means reported by users, not shown in controlled trials. Sources
Not recommendations. These are commonly cited ranges, shown so you can see what real-world use looks like.
| Plan | Dose | Frequency | Duration | Route |
|---|---|---|---|---|
| Trial-style titration (start) Phase 2 started most groups at 2 mg and stepped up every 4 weeks (2 → 4 → 8 → 12 mg). A lower start reduced GI side effects. | 2 mg | Once weekly | 4 weeks, then step up | Subcutaneous |
| Community-reported low start Some users start at 500 mcg–1 mg to test tolerance. Not a studied dose. | 1 mg | Once weekly | 4 weeks, then reassess | Subcutaneous |
| Trial maintenance (top dose) 12 mg was the highest phase 2 dose. Reached only after months of stepwise titration. | 12 mg | Once weekly | Trials ran 48–80 weeks | Subcutaneous |
Set up for Retatrutide. Switch vial size any time. Educational math only, not dosing advice.
At a common mix of 10 mg of Retatrutide in 2 mL of water (5 mg/mL), these commonly reported doses come to the following on a U-100 insulin syringe (100 units = 1 mL). They are examples of the arithmetic, not recommendations.
| Reported plan | Dose | Draw to | Volume |
|---|---|---|---|
| Trial-style titration (start) | 2 mg | 40 units | 0.4 mL |
| Community-reported low start | 1 mg | 20 units | 0.2 mL |
| Trial maintenance (top dose) This dose is more than the syringe or cartridge holds. Use a bigger one, or less water for a stronger mix. | 12 mg | 240 units | 2.4 mL |
Concentration (mg/mL) = vial mg ÷ mL of water; units = dose (mg) ÷ concentration × 100. A different vial size or amount of water changes every number above.
Amino Club sells Retatrutide as a research chemical. Its listings are research-use-only and not for human use; we show them for price tracking and their published lab reports.
Research-use-only listing — not for human use.
40% off through our link (code MYPEPSINFO applies automatically), until Dec 31, 2026.
| Size | Price | Per mg | Stock | Latest COA |
|---|---|---|---|---|
| 10 mg | $41.99 | $4.20 | In stock | 99.92% pure, lot RT0004 ILS Labs, tested Aug 21, 2026 |
| 20 mg | $80.99 | $4.05 | Out of stockNotify me | 99.93% pure, lot RT0005 ILS Labs, tested Jul 30, 2026 |
| 30 mg | $119.99 | $4.00 | In stock | 99.57% pure, lot RT0006 ILS Labs, tested Jul 30, 2026 |
List price, checked daily since Oct 7.
| Oct 7, 2026 | $69.99 | |
| Oct 8, 2026 | $69.99 | |
| Oct 9, 2026 | $69.99 | |
| Oct 10, 2026 | $69.99 | |
| Oct 11, 2026 | $69.99 | |
| Oct 12, 2026 | $69.99 | |
| Oct 13, 2026 | $69.99 | |
| Oct 14, 2026 | $69.99 | |
| Oct 15, 2026 | $69.99 | |
| Oct 16, 2026 | $69.99 | |
| Oct 17, 2026 | $69.99 | |
| Oct 18, 2026 | $69.99 | |
| Oct 19, 2026 | $69.99 | |
| Oct 20, 2026 | $69.99 | |
| Oct 21, 2026 | $69.99 | |
| Oct 22, 2026 | $69.99 | |
| Oct 23, 2026 | $69.99 | |
| Oct 24, 2026 | $69.99 | |
| Oct 25, 2026 | $69.99 | |
| Oct 26, 2026 | $69.99 | |
| Oct 27, 2026 | $69.99 | |
| Oct 28, 2026 | $69.99 | |
| Oct 29, 2026 | $69.99 | |
| Oct 30, 2026 | $69.99 | |
| Oct 31, 2026 | $69.99 | |
| Nov 1, 2026 | $69.99 |
HPLC purity from each published lab report; lowest 99.57%.
| Feb 4, 2026 | 99.79% | lot A1115 |
| Feb 4, 2026 | 99.93% | lot A0112 |
| May 29, 2026 | 99.85% | lot RT0001 |
| May 29, 2026 | 99.65% | lot RT0002 |
| May 29, 2026 | 99.77% | lot RT0003 |
| Jul 30, 2026 | 99.86% | lot RT0004 |
| Jul 30, 2026 | 99.93% | lot RT0005 |
| Jul 30, 2026 | 99.57% | lot RT0006 |
| Aug 21, 2026 | 99.92% | lot RT0004 |
| Aug 21, 2026 | 99.92% | lot RT0004 |
Amino Club list prices as of Nov 1, 2026; sale prices include the 40% applied through our link. Multi-buy: 2+ units 5% off, 3+ units 7.5% off, 10+ units 40% off. Prices change; confirm on the listing.
An email when it’s back in stock, its price drops, a sale starts, or its FDA or WADA status changes.
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All Retatrutide lab reports, lot by lot →
Diluent: Bacteriostatic water (0.9% benzyl alcohol) — allows multiple draws from one vial.
Amazon affiliate links. Disclosure
Powder
Freezer / fridge
Keep sealed vial in the freezer (−20 °C) for long-term storage; fridge (2–8 °C) is fine for a few weeks. Keep dry and out of light.
After mixing
~28 days
Refrigerate at 2–8 °C. Never freeze after mixing. Keep upright, capped, and out of light.
Travel
Keep cool
Short trips at room temperature are generally fine for powder; keep mixed vials cold.
Investigational drug from Eli Lilly. Phase 3 TRIUMPH trials reported positive results in 2025–2026; Lilly has said it plans to submit for FDA approval around early 2027. It cannot legally be compounded, and products sold as 'retatrutide' online are unregulated research chemicals.
Regulations change often — verify with the FDA, EMA, MHRA, Health Canada, TGA and WADA before acting.
Trial weight loss has been larger than tirzepatide's, but there is no published head-to-head trial yet. Side effects also scale with dose.
Stepping up every 4 weeks lets your gut adjust. In the phase 2 trial a 2 mg start caused fewer GI side effects than a 4 mg start.
No. It already covers the GLP-1 receptor (and GIP). Stacking incretin drugs adds side-effect risk with no studied benefit.
It depends on the mix. At a common mix of 10 mg of Retatrutide in 2 mL of water (5 mg/mL), 2 mg is 40 units (0.4 mL) on a U-100 insulin syringe. The formula is dose in mg ÷ concentration in mg/mL × 100. Change the vial size or water in the calculator and the units update. This is math, not a dose recommendation.
Bacteriostatic water (0.9% benzyl alcohol) — allows multiple draws from one vial. A common mix is 10 mg + 2 mL, which gives 5 mg/mL. Less water makes a stronger mix and fewer units per dose; more water makes a weaker mix and more units. Pick the amount that lands your dose on an easy-to-read line.
Refrigerate at 2–8 °C. Never freeze after mixing. Keep upright, capped, and out of light. Plan on about 28 days once it is mixed, and discard it sooner if it turns cloudy or has particles. The calculator shows how long a vial lasts at your dose and flags a vial that outlasts its shelf life.
Evidence rating (4/5): Large phase 2 RCT (NEJM 2023) and multiple positive phase 3 trials (TRIUMPH program). Not yet approved, and long-term safety data is still being collected.
Legal status: Investigational drug from Eli Lilly. Phase 3 TRIUMPH trials reported positive results in 2025–2026; Lilly has said it plans to submit for FDA approval around early 2027. It cannot legally be compounded, and products sold as 'retatrutide' online are unregulated research chemicals.
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