Short answer: It depends on the product, and only FDA-approved products have tested answers. Labels range from use immediately (Egrifta SV) to 7 days (Egrifta WR), 21 to 28 days (somatropin), 30 days (Novarel hCG) and 60 days (Pregnyl hCG), refrigerated. For research peptides like BPC-157 or TB-500 there is no published stability study of the mixed vial.
These figures are from each product's current US label. They apply to that product, made and tested by its manufacturer, mixed with the diluent it comes with. They are not evidence for a compounded or research vial of the same molecule.
| Product | After mixing / first use | Where to keep it | Diluent or form |
|---|---|---|---|
| Genotropin 5 mg, 12 mg cartridge (somatropin) | Up to 28 days | Refrigerator, 2-8°C | Two-chamber cartridge, diluent with metacresol |
| Genotropin MiniQuick | Up to 24 hours, single use | Refrigerator, 2-8°C | Two-chamber, no preservative |
| Humatrope cartridge (somatropin) | Up to 28 days | Refrigerator, 2-8°C; no more than 30 minutes a day at room temperature | Diluent with 0.3% metacresol |
| Omnitrope 5 mg, 10 mg cartridge (somatropin) | Up to 28 days | Refrigerator, 2-8°C | Ready-made solution |
| Omnitrope 5.8 mg vial (somatropin) | Within 21 days | Refrigerator, 2-8°C | Bacteriostatic water with 1.5% benzyl alcohol |
| Norditropin FlexPro (somatropin) | 4 weeks in fridge, or 3 weeks up to 25°C (77°F) | Refrigerator or up to 25°C | Ready-made solution |
| Novarel (hCG) | Within 30 days | Refrigerator, 2-8°C | Bacteriostatic water, 0.9% benzyl alcohol |
| Pregnyl (hCG) | Within 60 days | Refrigerator, 2-8°C | Water with 0.56% NaCl and 0.9% benzyl alcohol |
| Chorionic gonadotropin (Fresenius Kabi) | Within 60 days | Refrigerator, 2-8°C | Bacteriostatic water |
| Egrifta SV 2 mg (tesamorelin) | Use immediately; discard if not used | Do not refrigerate or freeze once mixed | Sterile water, 0.5 mL |
| Egrifta WR 11.6 mg (tesamorelin) | Discard 7 days after mixing | Room temperature 20-25°C; do not refrigerate once mixed | Bacteriostatic water, 1.3 mL |
Note the hCG spread: the same hormone carries 30 days on the Novarel label and 60 days on the Pregnyl and Fresenius labels. Each figure belongs to the product that was tested.
GLP-1 pens are already liquid, so there is no mixing. The clock that matters is the first use, or the time out of the fridge.
| Product | After first use or out of fridge | Temperature limit |
|---|---|---|
| Ozempic multi-dose pen | 56 days after first use | 15-30°C (59-86°F) or in the fridge |
| Wegovy single-dose pen or syringe | Up to 28 days out of the fridge, before the cap is removed | 8-30°C (46-86°F) |
| Wegovy FlexTouch multi-dose pen | 56 days after first use | 15-30°C (59-86°F) or in the fridge (section 16) |
| Mounjaro / Zepbound single-dose pen or vial | Up to a total of 21 days unrefrigerated | Not above 30°C (86°F) |
| Mounjaro / Zepbound KwikPen or multi-dose vial | 30 days after first use, 30 days total at room temperature, or 4 weekly doses, whichever comes first | Fridge or up to 30°C (86°F) |
| Saxenda / Victoza pen | 30 days after first use | 15-30°C (59-86°F) or in the fridge |
For compounded GLP-1 vials, FDA says multi-dose vials should be used within 28 days after first use because contamination risk rises after that, even if medicine is left. See the semaglutide and tirzepatide guides for vial math.
Honest answer: nobody has published it. No FDA label covers these, and we found no published study of how long the mixed vial stays stable in a fridge. Numbers like "30 days in the fridge" that circulate online are not backed by a peer-reviewed stability study we could find. Here is what published work does report:
| Peptide | What has been published | What it does not tell you |
|---|---|---|
| BPC-157 | Its developers describe it as stable in human gastric juice (review, 2013). A 2026 review notes no pharmaceutical formulation has been developed or validated. | How long a vial mixed with bacteriostatic water stays potent. |
| TB-500 / thymosin beta-4 | TB-500 is not full thymosin beta-4; an anti-doping study identified it as a fragment (Ac-LKKTETQ). Oxidized thymosin beta-4 (Met6 sulfoxide) was about 20 times weaker at its actin effect in a lab study. | Shelf life of either in solution. |
| Ipamorelin | No stability study found in PubMed; published work covers pharmacokinetics and doping detection. | Anything about vial storage. |
| Sermorelin / GHRH analogs | GRF degrades in water mainly by deamidation and is most stable at pH 4-5 (1992). One GHRH analog held up for at least 36 days at 4°C by HPLC (1996). The discontinued Geref ampoule (EU label) was to be mixed immediately before use. | Stability of a compounded sermorelin vial. |
| CJC-1295 | Studies report stability against a blood enzyme (DPP-IV) and a long half-life in the body. | Anything about the vial; body half-life is not shelf life. |
| GHK-Cu | Plain GHK (without copper) broke down under basic and oxidative stress in a forced-degradation study (2016). | Shelf life of the copper complex in a vial. |
If you use these, a fresh-mixed, refrigerated, light-protected vial and a recorded mix date are the general practices; they are not a validated expiry. Compound pages: BPC-157 (5 mg, 10 mg), TB-500, ipamorelin, sermorelin, CJC-1295, GHK-Cu.
In water, peptides are exposed to chemical reactions such as deamidation, oxidation and hydrolysis that are much slower in a dry powder. That is why proteins are often freeze-dried to reach an acceptable shelf life (Wang 2000; Manning 2010). Mixing starts the clock; contamination from repeated needle punctures is a second clock, which is why multi-dose vials carry a preservative and a discard date.
Related: bacteriostatic vs sterile water and the reconstitution calculator.