Storing Reconstituted Peptides: Fridge, Freezer & Shelf Life

Reconstituted peptides are biologically active molecules. They survive happily in the fridge for weeks but degrade rapidly with heat, light or mechanical shock. This guide covers the specifics.

Lyophilised (unreconstituted) vials

Freeze-dried peptide is remarkably stable. Most peptides will keep for 18–24 months at –20°C in a freezer, or 6–12 months refrigerated. Room temperature is fine for short transit windows of a few days.

Reconstituted vials

Once you add bacteriostatic water, store at 2–8°C in the fridge. Do not freeze. The standard shelf life is 28 days, though some shorter peptides (e.g. IGF-1 LR3) drop to 14 days.

Where to put the vial in your fridge

• Middle shelf, towards the back, but not touching the back wall.
• Avoid the door — temperature swings every time it opens degrade the peptide faster.
• Avoid the very back wall — many fridges drop below 0°C there, freezing the vial.

Travel and short-term storage outside the fridge

Peptides survive several hours at room temperature without significant degradation. For longer trips use a small insulated medicine pouch with an ice pack — but never let the vial touch the ice directly.

Signs your peptide has degraded

• Cloudiness or floating particles
• Yellow or brown discolouration
• Off smell
• Sudden loss of expected effect at the same dose

If you see any of these, discard the vial.

Frequently asked questions

Can I freeze reconstituted peptide?

No. The freeze–thaw cycle breaks peptide bonds and you lose potency. Refrigerate instead.

What temperature exactly?

Between 2°C and 8°C. Most UK domestic fridges hover at 3–5°C, which is ideal.

How long can it sit at room temperature?

A few hours is fine. Overnight is risky. Always return to the fridge as soon as possible.

Does light matter?

Yes — UV degrades peptides. The amber glass vial gives basic protection; keeping it in a box inside the fridge is better.