Quick answer: Reconstituted Semaglutide is generally held to be stable for 28 to 56 days refrigerated at 36-46°F (2-8°C), with 28 days as the conservative beyond-use date. Enter your reconstitution date above to turn that into your own discard-by date.
How long does Semaglutide last once mixed?
Reconstitution starts the stability clock. Dry, lyophilized powder holds for months because there is almost no water available to drive hydrolysis and oxidation. The moment bacteriostatic water goes in, those reactions restart and the window drops from months to weeks.
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. The range rather than a single number reflects the variables: sterile technique at reconstitution, how steady your refrigerator actually runs, and day-to-day handling. Use the conservative 28 days when you are unsure.
Why the calculator refuses some combinations
Three 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 freezer: this is the recommended long-term condition, sealed and protected from moisture, but there is no published day count to convert into a discard date.
Worked example
Reconstitute a Semaglutide vial on the 1st of a month and refrigerate it at 36-46°F (2-8°C). The conservative beyond-use date lands 28 days later, and the outer limit at 56 days. 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 Semaglutide last once mixed with BAC water?
Generally 28 to 56 days refrigerated at 36-46°F (2-8°C), with 28 days as the conservative figure. Enter your own reconstitution date above for the exact discard-by date.
How long does unmixed Semaglutide powder last?
Lyophilized powder refrigerated at 36-46°F (2-8°C) is generally considered suitable for use within 3 to 6 months. Beyond that, the standard recommendation is a freezer at -20°C (-4°F) or below, sealed and dry.
Can I freeze reconstituted Semaglutide?
No. Ice crystal formation disrupts the peptide structure and can reduce or destroy potency. Discard a reconstituted vial that has frozen. Only the dry powder is stored frozen.
How long can reconstituted Semaglutide 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: Semaglutide is the active ingredient in FDA-approved GLP-1 medications. 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.