Guide
Peptide storage and stability
Most peptide degradation happens through heat, moisture, light and repeated temperature cycling. Good storage is simple once you know which state the peptide is in.
Lyophilised (powder) peptides
- Short term (weeks): room temperature is generally fine, away from light and heat. Peptides ship unrefrigerated for this reason.
- Medium term (months): refrigerate at 2–8 °C.
- Long term (a year or more): freeze at −20 °C or colder, sealed, with a desiccant if possible.
- Let frozen vials warm to room temperature before opening, to avoid condensation.
Reconstituted peptides
- Refrigerate at 2–8 °C. Never leave in a warm car or in sunlight.
- Most are stable for 3–4 weeks when made with bacteriostatic water; some (such as GLP-1 analogues in pharmaceutical pens) are formulated to last longer.
- Avoid freezing reconstituted peptides unless you have split them into single-use aliquots — freeze-thaw cycles damage them.
Signs of degradation
- Cloudiness, particles or colour change (except GHK-Cu, which is naturally blue).
- Powder that has collapsed into a sticky film — a sign of moisture exposure.
- Foam that does not settle.
Chemical degradation (oxidation, deamidation) is often invisible; only HPLC testing can confirm it. See reading a COA.
Frequently asked questions
Do peptides need to be refrigerated?
Lyophilised peptides tolerate room temperature for weeks but are best refrigerated for longer storage. Reconstituted peptides must be refrigerated.
Can you freeze peptides?
Lyophilised peptides freeze well. Reconstituted peptides should only be frozen as single-use aliquots to avoid freeze-thaw cycles.
How long do peptides last unrefrigerated?
Sealed lyophilised peptides typically last weeks to months at room temperature. Reconstituted peptides should not be left unrefrigerated.