What Is Bacteriostatic Sodium Chloride 0.9%?

• Bacteriostatic sodium chloride, bacteriostatic saline and BAC saline are three names for the same product.
• It is isotonic 0.9% sodium chloride with benzyl alcohol added as a bacteriostatic preservative.
• The preservative is what allows a sealed multi-dose vial to be entered more than once — it is the same agent used in bacteriostatic water.
• Plain 0.9% sodium chloride for injection has no preservative and its vial is labelled for a single withdrawal.

Bacteriostatic sodium chloride is isotonic 0.9% sodium chloride solution with benzyl alcohol added as a bacteriostatic preservative, supplied in a sealed multi-dose vial. If that sentence contains three terms you were not sure about, this guide takes them one at a time.

Three names, one product

The naming causes more confusion than the chemistry does. Bacteriostatic sodium chloride, bacteriostatic saline and BAC saline all describe the same thing. Sodium chloride is the salt; a solution of it in water is what "saline" means; and BAC is simply the common abbreviation of bacteriostatic. Product labelling generally uses the sodium chloride form, which is why the formal name and the term people search rarely match.

What the 0.9% means

0.9% is the concentration of sodium chloride in the solution — 9 mg per mL. That figure is not arbitrary: at 0.9% the solution is isotonic, meaning its effective osmotic concentration matches that of the reference solution. This is why 0.9% sodium chloride is the standard example whenever isotonic saline is described, and why the percentage is part of the product's name rather than a footnote.

What the preservative does

Benzyl alcohol is the bacteriostatic agent. "Bacteriostatic" means it inhibits the growth of most common bacteria rather than necessarily killing them — a distinction covered in full in how the 0.9% benzyl alcohol preservative works. The practical consequence is the whole point of the product: because growth is held in check after the seal is broken, the vial can be entered more than once instead of being discarded after a single withdrawal. That protection is finite, so a fixed in-use period still applies from first entry — see how long a vial lasts once opened.

Versus plain saline

This is the comparison most often got wrong. Plain 0.9% Sodium Chloride Injection USP — the ordinary saline vial — contains no preservative at all. Its salt concentration is identical, its appearance is identical, and its vial is labelled for a single withdrawal precisely because there is nothing inhibiting growth once it has been entered. The bacteriostatic version is not stronger, purer or more concentrated saline. The only difference is the preservative, and the only thing the preservative changes is how many times the vial can be accessed.

Versus bacteriostatic water

Both are preserved with benzyl alcohol and both come as multi-dose vials, so the preservative is not the difference here — the solute is. Bacteriostatic water contains no solute at all; bacteriostatic saline is isotonic 0.9% sodium chloride. Which of the two a given product requires is stated in that product's own manufacturer information, and that specification decides it. It is not a preference, and the two are not interchangeable on the basis that both are clear liquids in similar vials. The longer comparison is in bacteriostatic saline vs bacteriostatic water.

The Australian presentation

The presentation Aus BAC Supply stocks is the original Hospira bacteriostatic 0.9% sodium chloride 30 mL multi-dose vial — a plastic flip-top vial, sterile and non-pyrogenic, released against the USP monograph, supplied factory-sealed and unaltered. It is available singly and in 2- and 3-vial packs, dispatched from Melbourne with tracked delivery Australia-wide.

These products are diluents or solvents, not ready-to-administer medicines. Never inject them by themselves or self-administer. Compatibility, preparation, storage and disposal must follow the supplied manufacturer product information under qualified healthcare-professional direction.