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Basics & Technique

How long does my mixed vial last?

Updated 2026-05-02

Mixed with BAC water, your peptide lasts about 28 days in the fridge. That works because BAC water contains a preservative (benzyl alcohol) that keeps bacteria from growing. Mixed with plain sterile water, it lasts 24 to 48 hours. No preservative, no multi-use. Big difference.

IfIf you use BAC water
Thenthen write the mix date on the vial and discard at day 28
IfIf you only have sterile water
Thenthen mix only what you'll use in one day
IfIf a vial spent time warm during those 28 days
Thenthen the clock is shorter (see room temp question)
Key facts
  • BAC water contains 0.9% benzyl alcohol - that's the preservative
  • USP-aligned guidance: 28 days refrigerated for multi-dose preserved preparations
  • Store at 36 to 46 F (standard fridge); do not freeze reconstituted peptide
  • After day 28, discard even if it looks clear; preservative effectiveness can't be guaranteed
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