Retatrutide calculator
An investigational triple receptor agonist studied for obesity and metabolic disease. Not available as an approved medicine.
Also known as: LY3437943
FDA status — not an approved drug Investigational. Retatrutide is not FDA-approved for any use and remains in clinical trials. Material sold outside a trial is not an approved drug.
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What Retatrutide is
Retatrutide is an investigational triple agonist targeting the GIP, GLP-1, and glucagon receptors. Phase 2 results reported the largest average weight reductions yet seen in this drug class, which is why it circulates widely despite not being approved.
Research depth: 4/5 Substantial and growing: published phase 2 human results with phase 3 underway, on top of solid preclinical pharmacology. Human trials: Phase 2 complete, phase 3 ongoing. This measures how much has been studied — counting animal and laboratory work — not whether it works for you.
How Retatrutide works
It adds glucagon receptor activation to the dual mechanism of tirzepatide. Glucagon signaling raises energy expenditure and promotes hepatic fat mobilization, so the theory is that it burns more while the GLP-1 and GIP arms reduce intake. That third mechanism is also why its long-term cardiovascular and hepatic safety profile is still an open question.
Retatrutide side effects
Commonly reported
- Nausea and vomiting
- Diarrhea and constipation
- Decreased appetite
- Increased heart rate — reported more with this compound than with GLP-1-only agents
Serious — seek medical care
- Pancreatitis
- Clinically significant tachycardia
- Unknown long-term risks — as an investigational compound, its complete safety profile has not been established
This list is not exhaustive. Report anything unexpected to the clinician who prescribed it. If you have severe abdominal pain, trouble breathing, or signs of an allergic reaction, seek care the same day. See also our guide to peptide side effects by class.
A worked example
A 10 mg vial reconstituted with 2 mL of bacteriostatic water gives 5 mg/mL. A 1000 mcg dose is then 0.2 mL — about 20 units on a 100-unit insulin syringe, giving roughly 10 doses per vial before accounting for residual volume left in the vial and syringe.
Prefer paper? Download the printable Retatrutide dosing chart (PDF) — every vial size and water volume in syringe units, with the same review byline as this page. All charts →
Commonly cited dose range
Figures circulating for Retatrutide run from 500 mcg to 12000 mcg. Doses appearing in published trial protocols escalate slowly over many weeks. This is investigational data, not a prescribing guide.
Read this as reference information, not instruction. These numbers describe what is commonly discussed, not what is right for any individual. Dose, frequency, and whether to use Retatrutide at all are decisions for a licensed clinician who knows your history.
Common questions
Is retatrutide approved?
No. Retatrutide is an investigational compound in clinical development and has not been approved by the FDA for any indication.
How do I reconstitute a 10 mg retatrutide vial?
The arithmetic matches any lyophilized peptide: 10 mg with 2 mL of bacteriostatic water yields 5 mg/mL, so 1 mg is 0.2 mL, or 20 units on a 100-unit insulin syringe.