Short answer: 28 days after first opening, per Hospira's labeling. After that, the vial should be discarded — even if water remains.

Why 28 days?

Bacteriostatic water contains 0.9% benzyl alcohol, a preservative that inhibits bacterial growth between withdrawals. The preservative's protection is not indefinite; 28 days is the window the manufacturer's labeling supports for a multi-dose vial once the stopper has been punctured.

Practical tips

Write the date you first open the vial directly on the label — it's the easiest way to know when the 28 days are up. Store the vial as directed on its label, keep the stopper clean (the alcohol prep pads in our kit are for exactly this), and never use water that looks cloudy or discolored.

What about unopened vials?

Unopened, sealed vials are good until the expiration date printed on the label.

Our Complete Peptide Starter Kit includes a sealed 30 mL multi-dose vial of genuine Hospira (Pfizer) Bacteriostatic Water for Injection, USP, plus the prep pads, syringes, and sharps container to go with it.

This page is general product information, not medical advice. Always follow the manufacturer's labeling.