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Storage 5 min read

Storing peptides

Every vial we ship is stable if it is kept cold, dark and closed. The details depend on whether it arrived as a powder or a solution.

HP Written by the Hello Peptides lab team · Updated August 2026

Two forms, two rules

Every Hello Peptides vial arrives one of two ways. Lyophilised vials hold a freeze-dried powder and are the most stable form of a peptide. Pre-mixed vials are already in solution and are the more delicate of the two. Storage comes down to which one is in front of you.

FormUnopenedAfter first puncture
Lyophilised vial2–8°C, up to 24 months from the batch dateReconstitute, then treat as pre-mixed
Pre-mixed vial2–8°C, use within 30 days of dispatch2–8°C, use within 28 days
Stack pens2–8°C, up to 12 months2–8°C, use within 28 days

Fridge, not freezer

The fridge door is the wrong shelf. It swings warm every time it opens. Keep vials in the body of the fridge, in their carton, away from the back wall where frost forms. Pre-mixed solutions should never be frozen: ice crystals shear the peptide chain and the purity figure on the certificate stops being true.

Lyophilised vials can be frozenUnopened lyophilised powder tolerates −20°C for long-term storage. Let the vial reach room temperature before opening it, so condensation forms on the outside of the glass rather than inside.

Light, heat and time

The cartons are not decoration. UV degrades peptides, so keep vials boxed until you need them. Above 25°C degradation speeds up sharply; a vial left on a sunny bench for an afternoon can lose more purity than a month in the fridge. Write the date on the label the first time you open it.

Signs a vial has turned

  • A pre-mixed solution has gone cloudy, or particles are visible when it is held to the light.
  • Lyophilised powder has collapsed into a glassy film, which means moisture has got in.
  • The stopper has lifted or the crimp is loose.
  • More than 28 days have passed since first puncture.

If any of these apply, do not use it. Contact us with the batch number and we will replace it.

Research use onlyProducts are supplied for laboratory research and are not for human or animal consumption, diagnosis or treatment. Questions about a batch? Contact the lab with the batch number.
Keep reading All guides →
Preparation Reconstituting a lyophilised vial Water, volumes and the concentration maths, with a calculator. 6 min read Handling Aseptic handling in the lab Keeping vials sterile from first puncture to disposal. 4 min read Quality Reading a batch certificate What the HPLC trace, mass spec and purity figure actually tell you. 5 min read