Quick answer: Use a reconstituted Retatrutide vial within 28 days after first use, refrigerated at 36-46°F (2-8°C), then discard it even if medication remains (FDA advice for multi-dose vials). Enter your reconstitution date above to turn that into your own discard-by date.
How long does Retatrutide last once mixed?
Reconstitution starts the stability clock. Dry, lyophilized powder is more stable because there is almost no water available to drive hydrolysis and oxidation. The moment bacteriostatic water goes in, those reactions restart. The 28-day discard date that then applies is FDA's recommendation for multi-dose vials, set by contamination risk, not a Retatrutide stability figure.
Bacteriostatic water contains 0.9% benzyl alcohol as a preservative, which is what makes a multi-dose vial viable at all and what stretches the beyond-use date past a single use. US Pharmacopeia General Chapter <797> is the governing standard for sterile compounding and sets the beyond-use dating framework most pharmacies apply. FDA advises using a multi-dose vial within 28 days after first use because the contamination risk rises after that, and to discard it at 28 days even if a seller or compounder says it lasts longer. No FDA label or published study gives a longer in-use period for a mixed Retatrutide vial.
Why the calculator refuses some combinations
Five of the six rows in the table above have no published beyond-use figure, so the calculator returns a state instead of a date:
- Reconstituted in a freezer: freezing a reconstituted vial forms ice crystals that physically disrupt the peptide. If a mixed vial freezes, discard it. Do not thaw and use it.
- Room temperature: Brief excursions at room temperature for dose preparation are acceptable, but there is no published beyond-use figure for storing a vial at room temperature. This calculator will not produce a discard date for it. Return the vial to the refrigerator and check with your compounding pharmacy or prescriber.
- Lyophilized in a refrigerator: Retatrutide has no FDA-approved label and no published shelf life for the unmixed powder, so any date a seller prints on the vial is the seller's own claim.
- Lyophilized in a freezer: no FDA-approved label or published stability study gives a freezer rule for the unmixed powder, so there is nothing to convert into a discard date. Follow the storage directions that came with the vial.
Worked example
Reconstitute a Retatrutide vial on the 1st of a month and refrigerate it at 36-46°F (2-8°C). The discard date lands 28 days later. Write the reconstitution date on the vial label before it goes in the fridge. That label is the only reliable record of where you are in the window. If there is any doubt about when a vial was mixed, treat it as expired.
Frequently asked questions
How long does Retatrutide last once mixed with BAC water?
28 days after first use, refrigerated at 36-46°F (2-8°C), then discard it (FDA advice for multi-dose vials). Enter your own reconstitution date above for the exact discard-by date.
How long does unmixed Retatrutide powder last?
Retatrutide has no FDA-approved label and no published shelf life for the unmixed powder, so any date a seller prints on the vial is the seller's own claim. Keep it sealed and follow the storage directions that came with the vial.
Can I freeze reconstituted Retatrutide?
No. Ice crystal formation disrupts the peptide structure and can reduce or destroy potency. Discard a reconstituted vial that has frozen.
How long can reconstituted Retatrutide sit at room temperature?
Brief excursions at room temperature for dose preparation are acceptable, but there is no published beyond-use figure for storing a vial at room temperature. This calculator will not produce a discard date for it. Return the vial to the refrigerator and check with your compounding pharmacy or prescriber.
Safety: Retatrutide is an investigational compound and is not approved by the FDA. This tool is educational only and does not recommend a dose or certify that any vial is safe to use. Beyond-use dates should come from your compounding pharmacy or prescriber; follow their labeled date over any figure shown here. Inspect every vial before use and discard it if the solution is cloudy, discolored, or contains particles.