Bacteriostatic Water

Active substance: sterile water containing 0.9% benzyl alcohol

Other names: Bacteriostatic Water, Sterile Water, Water for Injection.

Water can contain bacteria, but rather than killing off bacteria, bacteriostatic water prevents it from reproducing.

Effects of Bacteriostatic Water:

Bacteriostatic water is water that has been made to inhibit the growth of most types of bacteria. It is comprised of sterile and filtered water, with all bacteria removed, which is then mixed with 0.9% benzyl alcohol, which prevents any contaminating bacteria from growing in the water. In this way, the water has become ‘static’, or relatively unchanging in its bacterial content.

Bacteriostatic water is used to dilute or dissolve medications for patient injection. It is different from sterile water, which is filtered and purified but has no additives, and is usually only available for single-use.

You might ask yourself, why doesn’t bacteriostatic water just use an agent that kills bacteria outright? It’s true, bacteriostatic water doesn’t contain an anti-bacterial agent like some other fluids for injection, so it doesn’t kill bacteria off – it just prevents bacteria from growing in the water. But anti-bacterial agents can have adverse reactions to medications, while benzyl alcohol doesn’t. Therefore, bacteriostatic water can be used for a broader array of drug dilutions or injections without negatively interacting with bacteria-destroying additives.

Sterile and bacteriostatic water contain no bacteria, but once they are used for the first time (usually by the insertion of a syringe) the container can become contaminated. This is why sterile water can only be used once. The advantage of bacteriostatic water is that bacteria that might contaminate it simply can’t grow and reproduce, or act as an infectious agent, and so can be used repeatedly.

Most manufacturers of bacteriostatic water recommend that any unused water be discarded after 28 days, just in case the benzyl alcohol has lost any of its efficiency in preventing bacterial growth over time.

Sometimes bacteriostatic water is made to inhibit bacterial growth using a salt solution instead of benzyl alcohol. The reasons depend on why the water is being used.

Side effects: febrile response, local tenderness, abscess, tissue necrosis or infection at the site of injection, venous thrombosis or phlebitis extending from the site of injection and extravasation.

How to use:

Bacteriostatic water can be injected in three main ways:

Intravenous injection is performed by accessing a vein with a needle.
Intramuscular injection accesses a muscle with a needle.
Subcutaneous injection means under the skin, with the root sub- meaning beneath, and cutaneous pertaining to the skin.

Each method is used based on the type of medication and the best path for it to be effective, as determined by a medical professional.