How long does a peptide last once mixed?

The short version: once reconstituted, most peptides are quoted at roughly 28 days refrigerated, about 60 days frozen if frozen only once, and just a few days at room temperature. Sealed powder lasts far longer. These are general figures — the real number depends on the compound, its purity and whether your water has a preservative, so follow your own vial's instructions.

The confusion almost always comes from treating a vial as one thing with one expiry date. It isn't. It has two clocks, and only one of them is ticking fast.

The two clocks

Sealed powderReconstituted (mixed)
Typical windowMonths to years~28 days fridge · ~60 days frozen · a few days warm
Clock startsAt manufactureThe moment you add water
Best keptFrozen for the long haulRefrigerated, used within its window

That second column is the one people forget. The instant water goes in, a fresh, much shorter countdown begins.

Why it varies so much between compounds

Some peptides are simply more fragile than others, and small things move the number: the concentration you mix to, whether the bacteriostatic water's preservative is present, how cold the fridge really runs, and how often the vial is taken in and out. Rather than memorise a figure per compound, it's easier to look it up and then date your own vial.

The shelf-life reference table lists refrigerated and frozen figures for every compound in the library, with the method, the limitations and the primary sources it's built from. If you'd rather get an exact expiry date from the day you mixed yours, the shelf-life calculator does that in one tap.

What shortens the window

Can I tell by looking?

Not reliably. Cloudiness, particles or a colour change are worth noticing — the filtering guide explains why cloudiness is information you shouldn't just filter away — but a vial can lose potency while still looking perfectly clear. There's no home test, so when a vial is well past its window the safe call is to start fresh.

Common questions

How long does GHK-Cu last once mixed?

Like most reconstituted peptides it's generally handled as a few weeks refrigerated. Check the exact figure in the reference table.

Does the powder expire too?

Yes, but far more slowly. Sealed lyophilised powder kept cold and dark lasts a long time; the short clock is the mixed one.

What's the single best habit?

Write the mix date on the vial. Our printable labels or the app's vial ledger do it for you so the one detail nobody remembers is on the glass.

While you're here

Shelf life calculatorExact expiry from the day you mixed it Fridge or room temp?Which vials need to stay cold Printable vial labelsNever guess a vial's age again