How Long Do Peptides Last in the Fridge?

Lyophilized (freeze-dried) peptides stored at 2–8°C (standard refrigerator temperature) typically remain stable for 12–24 months. Once reconstituted with bacteriostatic water, most peptides maintain potency for 14–30 days under refrigeration.

Lyophilized vs. Reconstituted Stability

Lyophilized powder: The freeze-dried form is the most stable. Kept sealed, protected from light, and refrigerated at 2–8°C, most research peptides retain >95% purity for 1–2 years. For long-term storage beyond 6 months, a -20°C freezer is optimal.

Reconstituted solution: Once dissolved in bacteriostatic water, peptides are more vulnerable to degradation. The benzyl alcohol in bacteriostatic water provides antimicrobial protection, extending usable life to approximately 28 days at 2–8°C. Using sterile water (without preservative) shortens this to 48–72 hours.

Factors That Affect Peptide Shelf Life

Temperature fluctuations are the biggest enemy. Each freeze-thaw cycle denatures a portion of the peptide. Store vials in the back of the fridge (most consistent temperature), never in the door. A study on peptide stability found that repeated temperature cycling reduced bioactivity by up to 30% within 10 cycles (PMID: 25456785).

Light exposure accelerates oxidation, particularly for methionine-containing peptides. Keep vials in amber glass or wrapped in foil. Contamination from non-sterile technique is the most common cause of premature degradation — always use alcohol-swabbed vial tops and sterile syringes.

Quick Reference

Form	Temperature	Expected Stability
Lyophilized	2–8°C (fridge)	12–24 months
Lyophilized	-20°C (freezer)	2–5 years
Reconstituted (BAC water)	2–8°C	14–30 days
Reconstituted (sterile water)	2–8°C	48–72 hours

Related Resources

• How to Store Peptides Properly: Full Guide
• Bacteriostatic Water
• How to Reconstitute Peptides

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Written by NorthPeptide Research Team · For laboratory and research use only. Not for human consumption.

Written by NorthPeptide Research Team