H2O Side Effects Center

Last updated on RxList: 10/13/2021
H2O Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

What Is Bacteriostatic Water?

Bacteriostatic Water (bacteriostatic water for injection) is sterile water containing 0.9% benzyl alcohol that is used to dilute or dissolve medications; the container can be reentered multiple times (usually by a sterile needle) and the benzyl alcohol suppresses or stops the growth of most potentially contaminating bacteria. Bacteriostatic Water is available generically and has the same name. The Bacteriostatic Water can be used in diluting drugs that can subsequently be administered by intravenous, intramuscular, or subcutaneous injection.

What Are Side Effects of Bacteriostatic Water?

There are few side effects of Bacteriostatic Water, if any, in adults and if they occur, it they may be related to contamination, particulate matter or the drug that is being dissolved (see below). Side effects that may occur after drugs are added to Bacteriostatic Water include fever, abscess formation, venous thrombosis or phlebitis, tissue death, and infections.

Dosage for Bacteriostatic Water

Bacteriostatic Water for Injection is supplied in a multiple-dose 30 mL plastic fliptop vial that is plastic and not pressurized. It is not used for neonatal medications because of possible blood pressure changes and toxicity of benzyl alcohol. If Bacteriostatic Water is injected intravenously without any diluted compound, it may cause some red blood cell lysis because it is not isotonic.

What Drugs, Substances, or Supplements Interact with Bacteriostatic Water?

Bacteriostatic Water usually does not interact with other drugs; however, some drugs for injection may be incompatible. Tell your doctor all medications and supplements you use.

Bacteriostatic Water During Pregnancy or Breastfeeding

Tell your doctor if you are pregnant before receiving Bacteriostatic Water. Consult your doctor before breastfeeding.

Additional Information

Our Bacteriostatic Water Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


According to the USDA, there is no difference between a “portion” and a “serving.” See Answer
H2O Professional Information


Reactions which may occur because of this solution, added drugs or the technique of reconstitution or administration include 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.

If an adverse reaction does occur, discontinue the infusion, evaluate the patient, institute appropriate countermeasures, and if possible, retrieve and save the remainder of the unused vehicle for examination.

Although adverse reactions to intravenous, intramuscular or subcutaneous injection of 0.9% benzyl alcohol are not known to occur in man, experimental studies of small volume parenteral preparations containing 0.9% benzyl alcohol in several species of animals have indicated that an estimated intravenous dose up to 30 mL may be safely given to an adult without toxic effects. Administration of an estimated 9 mL to a 6 kg infant or neonate is potentially capable of producing blood pressure changes.

Read the entire FDA prescribing information for H2O (Bacteriostatic Water for Injection)


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© H2O Patient Information is supplied by Cerner Multum, Inc. and H2O Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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