Peptide Storage & Shelf Life (2026): How to Store Peptides

Before reconstitution (lyophilized powder)

Lyophilized (freeze-dried) peptides are the most stable form. Kept cold and dry, sealed vials generally last a long time. Guidance:

• Long-term: freezer (around −20 °C).
• Short/medium-term: refrigerator.
• Always: protect from light and moisture; keep sealed until use.

After reconstitution (in bacteriostatic water)

Once mixed with bacteriostatic water, a peptide is far less stable. Keep the reconstituted vial refrigerated and out of light. The benzyl-alcohol preservative in bacteriostatic water is what allows a multi-draw vial to be used over several weeks when refrigerated — plain sterile water offers no such protection.

Key rules

• Never leave vials at room temperature longer than necessary.
• Avoid repeated freeze-thaw of reconstituted solution — it degrades peptides.
• Don't shake hard; swirl gently.
• Label with the reconstitution date.

Quick reference

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Frequently asked questions

How do you store peptides before mixing?

Keep lyophilized (freeze-dried) peptides cold, dry and out of light — freezer for long-term storage, refrigerator for shorter term — and sealed until use. In that form they are stable for months to years.

How long do reconstituted peptides last?

Once mixed with bacteriostatic water and kept refrigerated and out of light, reconstituted vials are generally usable for several weeks. The benzyl-alcohol preservative suppresses bacterial growth for multi-draw use.

Can you freeze reconstituted peptides?

Repeated freeze-thaw cycles degrade peptides, so reconstituted solution is best kept refrigerated rather than repeatedly frozen and thawed.