What is Bacteriostatic Water

Bacteriostatic water is a highly purified, sterilized water used to dissolve medications or dilute medications to the appropriate consistency for injection. Bacteriostatic water (BW) is a sterilized water that contains .9% benzyl alcohol and has a pH of about 5.7. The alcohol in the water helps prevent the growth of most forms of bacteria which makes it ideal for diluting any drug that will be administered by intramuscular, intravenous, or subcutaneous injection.

Bacteriostatic water is not used for neonatal medications because it contains benzyl alcohol, which is toxic, and can cause blood pressure changes in babies under four weeks of age. BW for injection is provided in unpressurized, 30 mL plastic vials, specially formulated from polyolefin. It is a copolymer of propylene and ethylene, and is considered safe plastic according to USP biological standards for plastic containers and the animal testing which took place to confirm its safety. The plastic container for bacteriostatic water doesn’t require a vapor barrier to maintain the proper volume.

Most sources recommend that bacteriostatic water is used within 28 days of opening the vial. The preservatives will allow it to keep safely for up to 30 days.

Potential Side Effects of Bacteriostatic Water

There are not many side effects associated with using bacteriostatic water. When there are side effects, it’s probably more related to the drug that is dissolved in the bacteriostatic water, or some sort of contamination of the water prior to use.

If bacteriostatic water is injected by intravenous without a compound diluted in the water, it can cause red blood cell lysis. Lysis is the breaking down of a cell or membrane, which can be caused also by viruses or osmotic mechanisms which compromise the red blood cell’s integrity.

Side effects from bacteriostatic water have been reported to include:

  • Abscess formation
  • Death of tissues
  • Fever
  • Venous thrombosis or phlebitis
  • Infection at the site of injection
  • Febrile response

If using bacteriostatic water and you experience adverse side effects, discontinue use and check with a doctor. Save the unused water in case the doctor wants to inspect it for contamination or possible causes of adverse reactions.

Difference Between Sterile Water and Bacteriostatic Water

While both bacteriostatic and sterilized water are sterile liquids, they do have some differences you should be aware of. You cannot simply replace bacteriostatic water with sterile water as they are not the same thing. Sterile water doesn’t have any preservatives in it to prolong its life, which means it can only be used for a single injection. It doesn’t have a shelf life once the container is opened and it has been used. Think of sterile water as single-use packages. Bacteriostatic water contains benzyl alcohol as a preservative that prevents the growth of bacteria and allows the water to be used for multiple injections spread out over about 28 to 30 days. If your medication says to dilute or mix with bacteriostatic water, you do not want to substitute sterile water in its place or you risk getting an infection and experiencing adverse side effects.


Leave a Reply

Your email address will not be published. Required fields are marked *