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Supplies · two labels
Bacteriostatic water vs sterile water
No, they are not the same. Bacteriostatic water has benzyl alcohol in it and comes in a vial built to be opened again. Sterile water has nothing added and comes in a vial built to be used once and thrown away.
Source: Hospira labels for both products, read 2026-08-13
What matters first
Both are water, both are sterile, and both are prescription products. The added preservative is the only chemical difference, and every other difference follows from it.
The two labels, line for line
| Bacteriostatic Water for Injection, USP | Sterile Water for Injection, USP | |
|---|---|---|
| Anything added | Benzyl alcohol | Nothing |
| Container | Multiple-dose vial | Single-dose vial |
| Can you go back in | Yes — the label says repeated withdrawals may be made | No — the label supplies it only in single-dose vials |
| Newborns | Must not be used | This is the one the label sends you to instead |
| Storage | 20 to 25°C (68 to 77°F), which USP calls controlled room temperature | 20°C to 25°C (68°F to 77°F), which USP calls controlled room temperature |
The sentence that separates them
Each label opens with a description of what is in the vial. Put the two openings next to each other and the difference is one clause long.
Bacteriostatic Water for Injection, USP
“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. It is supplied in a multiple-dose container from which repeated withdrawals may be made”
Sterile Water for Injection, USP
“a sterile, nonpyrogenic preparation of water for injection which contains no bacteriostat, antimicrobial agent or added buffer and is supplied only in single-dose containers to dilute or dissolve drugs for injection”
One says “multiple-dose container from which repeated withdrawals may be made”. The other says “supplied only in single-dose containers”. That is the whole comparison, and everything sold on this topic is a restatement of it.
Which one do you need?
Follow the instructions for the drug you are dissolving. Where those instructions do not exist, neither label tells you, and any confident answer you read came from somewhere other than a label.
What the labels do settle is the shape of the choice. If a vial will be opened once and finished, either water fits and the preservative buys nothing. If it will be opened several times over weeks, only one of the two was built for that.
And there is one place where the labels are not neutral at all. For a newborn, the bacteriostatic version is barred outright and the sterile version is what the warning names.
“Benzyl alcohol, a preservative in Bacteriostatic Water for Injection, USP has been associated with toxicity in neonates. Data are unavailable on the toxicity of other preservatives in this age group. Where water is required for preparing or diluting medications for use in neonates, only preservative-free Sterile Water for Injection should be used.”
Next
- Bacteriostatic Water for Injection, USP — Hospira, Inc. (DailyMed SPL)retrieved 2026-08-13FDA label
- Sterile Water for Injection, USP — Hospira, Inc. (DailyMed SPL)retrieved 2026-08-13FDA label