Direct comparison
Bacteriostatic Water vs Reconstitution Solution
Bacteriostatic water is one diluent, reconstitution solution is the role. Two DailyMed labels compared on preservative, pH, container and neonate warning.
Written and maintained by CASRAI Editorial Board
Last updated
How do Bacteriostatic Water for Injection (benzyl alcohol) and Sterile Water for Injection (no preservative) compare side by side?
The table below compares Bacteriostatic Water for Injection (benzyl alcohol) and Sterile Water for Injection (no preservative) across 10 dimensions, from label wording for what it is to when to pick each.
Side-by-side comparison
| Dimension | Bacteriostatic Water for Injection (benzyl alcohol) | Sterile Water for Injection (no preservative) |
|---|---|---|
| Label wording for what it is | "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" | "a sterile, nonpyrogenic preparation of water for injection which contains no bacteriostat, antimicrobial agent or added buffer" |
| Preservative | Benzyl alcohol: 9 mg/mL in the 30 mL plastic vial and 11 mg/mL in the 20 mL fill in a 30 mL glass vial | None: no bacteriostat or antimicrobial agent |
| pH on the label | 5.7 (4.5 to 7.0) | 5.0 to 7.0 |
| Container type | Multiple-dose vials, "from which repeated withdrawals may be made" | Single-dose containers (prefilled syringes of 1, 2.5, 3, 5 and 10 mL on the label read) |
| Leftover contents | The label says to use aseptic technique for single or multiple entry and withdrawal; it gives no day count for discarding an opened vial | "Do not reuse single-dose containers. Discard unused portion." |
| Newborns | Warning: not for use in neonates. Benzyl alcohol "has been associated with toxicity in neonates", and only preservative-free Sterile Water for Injection should be used | No benzyl alcohol statement, because the product has no preservative |
| Without a drug dissolved in it | Intravenous administration without a solute may result in hemolysis; it must be made approximately isotonic prior to use | Intravenous administration without a solute may result in hemolysis; add sufficient solute to make an approximately isotonic solution |
| Stated use | Only for diluting or dissolving drugs for intravenous, intramuscular or subcutaneous injection; the label says parenteral preparations with benzyl alcohol should not be used for fluid replacement | Only for diluting or dissolving drugs, in the same wording |
| Storage | 20 to 25 C (68 to 77 F) | 20 to 25 C (68 to 77 F); protect from freezing |
| When to pick each | When the drug being mixed names a multiple-dose diluent in its own labeling and the patient is not a neonate (the label excludes neonates). | When the drug labeling calls for a preservative-free or single-dose diluent, including for neonates, as the drug manufacturer directs. |
Sources
- DailyMed, Hospira Bacteriostatic Water for Injection, USP label, https://dailymed.nlm.nih.gov/dailymed/services/v2/spls/87d6e9dc-fe3b-4593-ac9a-d7493d1959c7.xml (read 2026-11-01)
- DailyMed, Medefil Sterile Water for Injection, USP label, https://dailymed.nlm.nih.gov/dailymed/services/v2/spls/99e99a50-82d5-aff6-e053-2a95a90a8c56.xml (read 2026-11-01)
Ask CASRAI · free to try
Ask about Bacteriostatic Water vs Reconstitution Solution
Ask your first 2 questions free below. Subscribers get 150 a day for $29 a month.
An AI assistant specialized in research administration. It cites the sources behind every answer, labels web answers and says when it can't answer.
Answers draw on CASRAI's guides and dictionary plus the federal and funder documents we index: Federal Register, Grants.gov, Regulations.gov and UKRI.
Works on this site and inside Claude, Cursor and the AI tools you already use.
Everything CASRAI publishes — this page, the dictionary, the guides and the news — stays free to read, with no account and no card.
Common questions
Common questions about Bacteriostatic Water for Injection (benzyl alcohol) vs Sterile Water for Injection (no preservative)
Is bacteriostatic water the same as a reconstitution solution?
+
No. Reconstitution solution describes a job: the liquid used to dilute or dissolve a drug for injection. Bacteriostatic water is one product that can do that job, defined on its label as water for injection with benzyl alcohol added as a bacteriostatic preservative. Which diluent a given drug needs is stated in that drug's own labeling.
Can I use sterile water instead of bacteriostatic water?
+
The drug manufacturer's instructions decide which diluent applies. The two labels read differ in preservative and container type, and the bacteriostatic label says only preservative-free Sterile Water for Injection should be used for neonates. Follow the drug's labeling and your prescriber or pharmacist.
What can you use instead of bacteriostatic water? Is there a substitute or alternative?
+
The alternative on the labels read is Sterile Water for Injection, a preservative-free single-dose product, where the drug labeling allows it. Any other diluent has to be named by the drug's own labeling; it is not chosen by product name alone.
Is deionized water the same as bacteriostatic water?
+
No. Bacteriostatic water is defined on its label as sterile, nonpyrogenic water for injection with benzyl alcohol added. Neither label read describes deionized water; see the CASRAI comparison of distilled and sterile water for what those label words mean.
How does bacteriostatic water differ from distilled water?
+
Bacteriostatic water for injection is a labeled injection-diluent product with a stated preservative and sterile, nonpyrogenic wording. Distilled water is named for how it was made, not for an injection label; the linked distilled versus sterile water comparison covers the wording.
What about acetic acid water versus bacteriostatic water?
+
Neither label read describes acetic acid water. A drug that calls for a different diluent names it in its own labeling, so that labeling is the reference.
Why does the neonate warning matter?
+
The Hospira label states that benzyl alcohol "has been associated with toxicity in neonates" and that solutions containing benzyl alcohol must not be used in this patient population. That is why the preservative is the first label field to check.
Going deeper
