Benzyl alcohol at 0.9%, which is 9 mg/mL, is what makes water bacteriostatic. It is listed on the label as a bacteriostatic preservative, it comes with a warning that the product is not for use in neonates, and its presence is the single detail that separates bacteriostatic water from sterile water for injection.
The statement on the label
The Hospira prescribing information describes Bacteriostatic Water for Injection, USP as a sterile, nonpyrogenic preparation of water for injection containing 0.9% (9 mg/mL) or 1.1% (11 mg/mL) of benzyl alcohol added as a bacteriostatic preservative. The two percentages belong to two presentations: 0.9% in the 30 mL plastic fliptop vial, 1.1% in the 20 mL fill in a 30 mL glass vial. The percentage printed on the vial you hold is the one that applies to it.
AUBACWATER's own-label vials state 0.9% benzyl alcohol on every size. Bacteriostatic 0.9% sodium chloride, a different product, lists the same 0.9% (9 mg/mL) benzyl alcohol alongside 9 mg/mL of sodium chloride.
What a bacteriostatic preservative is for
The preservative is there because the container is a multiple-dose vial designed for repeated withdrawals. Its purpose, as the label puts it, is bacteriostatic: it inhibits bacterial growth in the opened container. The labels do not claim that it sterilises, that it treats anything, or that it has any effect beyond preservation, and neither does this article.
The contrast is Sterile Water for Injection, USP, whose label states that it contains no bacteriostat, antimicrobial agent or added buffer, which is why it is supplied only in single-dose containers with the unused portion discarded.
The warnings that travel with it
Every label that lists benzyl alcohol carries the same prominent warning: not for use in neonates. The Hospira prescribing information states that benzyl alcohol, a preservative in Bacteriostatic Water for Injection, USP, has been associated with toxicity in neonates, and the bacteriostatic sodium chloride label repeats the warning. The sodium chloride label adds not for inhalation.
For a buyer these warnings are identification facts: they tell you a preservative is present, and they are one more reason the preservative percentage should be read, recorded and matched to the product you intended to order. They are quoted here from the labels, and this article gives no guidance on use.
Three products, one line on the label
The same column of a label settles which product you have.
| Product | Benzyl alcohol | Other content | Container |
|---|---|---|---|
| Bacteriostatic water | 0.9% (9 mg/mL); 1.1% in one glass presentation | Water for injection only | Multiple-dose |
| Sterile water for injection | None | Water for injection only; no bacteriostat, antimicrobial agent or buffer | Single-dose |
| Bacteriostatic 0.9% sodium chloride | 0.9% (9 mg/mL) | Sodium chloride 9 mg/mL, isotonic | Multiple-dose |
Storage and records
All three labels state storage at 20 to 25 °C, described as USP controlled room temperature; the sterile water label adds protect from freezing. Keep the vial in its original labelled packaging so the preservative percentage, lot number and expiry date stay legible, and copy those details into your stock record on arrival.
What this article does not cover
It reports what the labels state about a preservative. It is not medical, veterinary or clinical advice and gives no guidance on preparing, mixing or using any product. AUBACWATER's own-label vials are supplied for laboratory use and are not for injection, infusion or administration.
Sources
- Bacteriostatic Water for Injection, USP, multiple-dose vial: prescribing information published by Hospira, Inc. (DailyMed, US National Library of Medicine; label revised August 2019)
- Sterile Water for Injection, USP, single-dose: prescribing information (DailyMed, US National Library of Medicine)
- Bacteriostatic 0.9% Sodium Chloride Injection, USP, multiple-dose vial: prescribing information published by Hospira, Inc. (DailyMed, US National Library of Medicine)
These guides support product comparison and stock organisation. Follow the exact product label and intended-use information for the presentation you choose.
