Peptide storage and stability after mixing

FDA label figures · Published studies · Sources · Reviewed October 17, 2026

Short answer: Keep mixed peptides refrigerated at 2-8°C (36-46°F), protect them from light, never freeze them, and follow the discard date on your product's label: 21-28 days for most somatropin, 30-60 days for hCG. Research peptides like BPC-157 have no published stability data for the mixed vial, so these guides say so instead of guessing.

What are the general rules for storing peptides?

Refrigerate after mixing unless your label says otherwise. Egrifta WR is the exception: room temperature, not the fridge.
Do not freeze. Every GLP-1 and somatropin label we checked says so.
Protect from light. Most labels say keep it in the original carton.
Date the vial. CDC, citing USP chapter 797, says opened multi-dose vials are dated and discarded within 28 days unless the manufacturer states another date.

Pick a question below. Each page cites the current US label or study for every number.

How long mixed peptides lastLabel days after mixing for HGH, hCG, tesamorelin and GLP-1 pens; what exists for research peptides. Bacteriostatic vs sterile water0.9% benzyl alcohol, multi-dose vs single-dose, the 28-day rule and the neonate warning. Left out of the fridgeExact room-temperature hours and days from each label, and the temperature ceiling. Can you freeze peptides?Every "do not freeze" statement on the labels, and lyophilized vs mixed. Traveling with injectablesTSA rules for liquids, syringes and ice packs, plus the label temperature limits to plan around.

Frequently asked questions

How should reconstituted peptides be stored?+

FDA-approved peptides mixed with a diluent are generally refrigerated at 2-8°C (36-46°F), protected from light and not frozen, and discarded after the label's day count. Egrifta WR is an exception and is kept at room temperature after mixing.

How long do peptides last after reconstitution?+

Per US labels: somatropin cartridges up to 28 days refrigerated, the Omnitrope vial 21 days, Novarel hCG 30 days, Pregnyl hCG 60 days, Egrifta WR 7 days. Research peptides have no published stability data for the mixed vial.

Do unmixed peptide vials need refrigeration?+

It varies. Novarel, Pregnyl and Egrifta powders are stored at room temperature before mixing; Genotropin cartridges, Humatrope and Omnitrope are refrigerated. Check your product label.

Sources

Reconstitution calculator · Compound guides · Supported medications