Retatrutide_
Also known as LY3437943, reta, triple G
An experimental weekly shot with some of the biggest weight-loss numbers yet in trials.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Retatrutide?
Plain language first. The technical label stays, but it never stands alone.Overview
Retatrutide is a triple agonist that switches on three hormone receptors at once: GLP-1, GIP, and glucagon. In plain terms: it copies three of your natural 'I'm full' and fat-burning signals together, which is why it drives some of the largest weight-loss numbers seen in trials. It is still experimental.
What it's used for
People follow it for very large weight loss, around a quarter to nearly a third of body weight in trials. It acts on three appetite and metabolism pathways at once.
How does Retatrutide work?
What it does in the body, and where.Retatrutide adds a third target, glucagon, to the two tirzepatide already hits. Glucagon is the interesting one, because it does something the others do not.
- 01GLP-1 and GIP reduce how much you eatThe same appetite and stomach-emptying effects as the approved drugs in this family.
- 02Glucagon raises how much you burnIt pushes your body to spend more energy at rest, rather than only taking in less. That is a different lever from the other two.
- 03More receptors has meant more weight loss, and more side effectsTrial figures are the largest in this class so far, but it is investigational, so nobody yet knows how it behaves over years.
Hits 3 receptors at once.
What else is it used for?
Each group carries its own evidence level.Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
Weight loss
Investigational- Human trialIn a 48-week mid-stage trial, average weight loss reached 24.2% on the top dose against 2.1% on placebo.
- Human trial83% of people on the top dose lost at least 15% of their body weight, and a quarter lost more than 30%.
- Human trialIn a late-stage trial reported in December 2025, average loss was 28.7% at 68 weeks, the largest late-stage weight-loss result reported so far.
- Human trialIn a second late-stage trial reported in May 2026, loss was roughly 25 to 28% at 80 weeks, with a subgroup reaching about 30% at two years.
Liver fat and joint pain
Investigational- Human trialFat in the liver dropped by 82.4% on average at 24 weeks, against essentially no change on placebo.
- Human trial86% of people reached a normal liver-fat level by 24 weeks, rising to 93% by 48 weeks.
- Human trialKnee osteoarthritis pain scores fell by up to 75.8%.
How much, and do you cycle it?
The range, and whether you take breaks.1 up to 12 mg per dose (start low, increase slowly), weekly. Not cycled in the trialsTrial dose
Given continuously for the whole study period: TRIUMPH-1, 80 weeks with an extension to 104. The dose is stepped up at the start, which is a ramp rather than a cycle, and no trial in this class built in a planned break.
How do I dose and price it?
Enter your vial and your dose. Pick a mix. We show the draw and the cost.The vial holds a fixed amount of drug. Adding more water does not make more drug, it just spreads it thinner, so you draw a bigger number on the syringe for the same dose.
Choose your mix
Measuring the water1 mL = one full 100-unit syringe.
Your draw
20 / 100 unitsHow do you store it?
Before mixing, and after.Dry powder in the freezer or fridge. Once mixed, fridge, and use within about a month.
Unmixed lyophilized Retatrutide keeps for a long time cold. Once you add water the clock starts: most reconstituted vials hold up for roughly 28 to 30 days at fridge temperature. Keep it out of light, and do not freeze it after mixing.
What are the side effects and cautions?
Known cautions and warnings for this compound.22 July 2026Not approved in any country. Phase 3 results were reported in 2026 but no approval application has been publicly announced.
Who should avoid it
- Not legally available outside clinical trials, so no prescriber is assessing whether it suits you
- Pregnancy, or trying to become pregnant
Stop and get help
- Severe stomach pain that spreads to your back
- Vomiting badly enough that you cannot keep fluids down
- Signs of an allergic reaction
Common effects
- Nausea, vomiting, and diarrhea, which increase at higher doses
- Odd skin sensations such as tingling or numbness, reported in trials
- Urinary tract infections
- A mild temporary rise in heart rate
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Retatrutide approved?
And where the numbers on this page come from.No. Not FDA-approved.
Not approved in any country. Phase 3 results were reported in 2026 but no approval application has been publicly announced.
- DoseFrom published clinical trials. Not approved by a regulator for this dose.
- Vial sizeFrom what vendors typically list; not a recommendation.
- Sources
- Reviewed22 July 2026
What else is like Retatrutide?
Others in Weight loss and metabolic, side by side.If you're weighing Retatrutide, it's worth reading Semaglutide, Tirzepatide, and Cagrilintide in the same class.
An experimental weekly shot with some of the biggest weight-loss numbers yet in trials.
- Dose
- 1 up to 12 mg per dose (start low, increase slowly)
- How often
- Weekly
The drug in Ozempic and Wegovy: a weekly shot that curbs hunger for steady weight loss.
- Dose
- 0.25 up to 2.4 mg per week (start low, increase slowly)
- How often
- Weekly
The drug in Mounjaro and Zepbound: a weekly shot for major weight loss and blood sugar.
- Dose
- 2.5 up to 15 mg per week (start low, increase slowly)
- How often
- Weekly
A weekly fullness-hormone shot, often paired with semaglutide for bigger loss.
- Dose
- 0.3 up to 4.5 mg per dose (start low, increase slowly)
- How often
- Weekly
10What these words mean
Show glossary +
What these words mean
- Titrate
- Starting at a low dose and increasing it slowly over time so your body adjusts and side effects stay mild.
- Subcutaneous
- An injection just under the skin, into the fat layer, usually with a short, thin insulin needle.
- Intramuscular (IM)
- An injection into a muscle, using a longer needle.
- Reconstitution
- Mixing a powdered peptide with liquid (bacteriostatic water) so it can be drawn into a syringe.
- Bacteriostatic water
- Sterile water with a tiny amount of preservative, used to mix powdered peptides.
- Concentration
- How strong the mixed peptide is, in milligrams per milliliter (mg/mL). More water makes it weaker; less water makes it stronger.
- Units (on the syringe)
- The marks on an insulin syringe. 100 units equals 1 mL. They measure how much liquid you draw, not the dose in milligrams.
- mcg and mg
- Units of dose. 1 milligram (mg) equals 1,000 micrograms (mcg).
- GLP-1
- A natural gut hormone that lowers appetite and blood sugar. Drugs that copy it, like semaglutide, are used for weight loss.
- Growth hormone secretagogue
- A compound that nudges your body to release more of its own growth hormone, rather than injecting the hormone itself.
- Half-life
- How long a compound stays active in your body. A longer half-life means you inject less often.
- Peptide vs small molecule
- A peptide is a short chain of amino acids. A few items here (like MK-677 or methylene blue) are small molecules, not true peptides, but people use them the same way.
- Research only
- No approved dose or use in people. Sold for research and not reviewed by the FDA for safety or quality.
- Investigational
- Still being tested in clinical trials and not yet approved or legally sold for general use.
- Banned in drug-tested sport
- Prohibited by the World Anti-Doping Agency (WADA); using it can disqualify a competing athlete.
Sources
- Drugs.com, retatrutide development history(2026)Development timeline confirming it remains unapproved.
- AJMC, TRIUMPH-1 phase 3 results(2026)TRIUMPH-1 phase 3, 2,339 participants over 80 weeks.
- Phase 2 trial, New England Journal of Medicine, 2023
- Liver fat substudy, Nature Medicine, 2024
Last reviewed 22 July 2026