How long reconstituted peptides last, peptide by peptide
By the Preptide Pro editorial team · Last reviewed 2026-11-03
For a multiple-dose vial, the best-supported general limit is 28 days after the first puncture, kept refrigerated, unless the manufacturer gives a different date. That comes from USP <797> and the Joint Commission. It is a sterility and preservative limit, not peptide-specific stability data, and most research peptides have no published in-use data at all.
The short answer: the 28-day multiple-dose rule
| Source | What it says |
|---|---|
| USP General Chapter <797> revision notice (USP-NF, 2020) | A multiple-dose container may be used for up to 28 days after it is first entered or punctured, unless the manufacturer specifies a different date. |
| The Joint Commission: Medication Management, multiple-dose vial FAQ | Discard an opened multiple-dose vial within 28 days unless the manufacturer specifies otherwise, and label the vial with the discard date rather than the date it was opened. |
| ASHP crosswalk of guidances and standards for single- and multiple-dose vials | Compares agency guidance side by side and shows the same 28-day limit for multiple-dose vials across them. |
Day 29 is not a cliff where the peptide breaks down. The rule exists because every puncture is a chance for contamination and the preservative has limits.
Is there published stability data for each peptide?
| Peptide | Published in-use stability data? |
|---|---|
| GHK-Cu | Yes, limited. GHK was stable in water and in pH 4.5–7.4 buffers for at least two weeks at 60 °C (Badenhorst et al.). That study did not test bacteriostatic water. |
| BPC-157 | None found. |
| TB-500 | None found. |
| CJC-1295 | None found. |
| Ipamorelin | None found. |
| Semaglutide / tirzepatide (compounded) | Compounded products carry their own beyond-use date. Follow the pharmacy label. |
“None found” means we did not find a peer-reviewed in-use stability study for the mixed product as of 2026-11-03. Online guides list different numbers of days for the same peptide; we don’t reproduce them because they don’t cite studies.
Bacteriostatic vs sterile water
Bacteriostatic water for injection contains 0.9% benzyl alcohol, a preservative intended for multiple-dose use. Sterile water for injection has no preservative, so it suits a single draw. The 28-day rule applies to preserved multiple-dose containers.
Storage basics
- Follow the manufacturer or pharmacy label first. It overrides the general rule.
- Keep mixed vials refrigerated and out of light.
- We found no peptide-specific study on freezing a mixed vial. Don’t assume freezing extends its life.
When to discard a vial
- It is past the discard date on its label.
- The solution is cloudy, discolored or has particles when it should be clear.
- The stopper is damaged or you think the vial was contaminated.
FAQ
Does a peptide go bad on day 29?
Should I write the opened date or the discard date on the vial?
How long does mixed compounded semaglutide or tirzepatide last?
How long does unmixed peptide powder last?
Sources
- USP General Chapter <797> revision notice (USP-NF, 2020)
- The Joint Commission: Medication Management, multiple-dose vial FAQ
- ASHP crosswalk of guidances and standards for single- and multiple-dose vials
- Badenhorst, Svirskis & Wu. Physicochemical characterization of native GHK. Pharm Dev Technol (2014/2016)
Storage information only, not medical advice. For prescribed or compounded products, follow your pharmacy label and your prescriber.