Bacteriostatic water benzyl alcohol: is it safe?
A preservative of 0.9% benzyl alcohol allows more than 1 draw from the same vial of bacteriostatic water for injection.
- Concentration: benzyl alcohol (0.9%)
- 9 milligrams per mL
- boxed label warning
- Newborns must not use this product
A standard vial label gives bacteriostatic water benzyl alcohol a strength of 0.9%; each 1 mL of water contains 9 mg. The added preservative stops bacteria from growing, which allows you to draw more than 1 time from the vial. Your medication dose is set by your prescriber, who also tells you which mixing water suits your vial.
Why is benzyl alcohol added to bacteriostatic water?
After a needle punctures the rubber stopper, plain sterile water contains nothing that stops germs. Adding 0.9% benzyl alcohol turns the liquid into bacteriostatic water, which is intended for multiple-dose vials. Taking small amounts over several days or weeks is possible without allowing bacteria to multiply inside the bottle.
You still need clean handling each time you use the bottle, even when it has a preservative. The label tells you to follow aseptic technique. This means keeping every point where a needle enters clean and germ-free. You can replace the vial on time by knowing how long opened bacteriostatic water remains usable.
Warnings on the bacteriostatic water benzyl alcohol label
The Hospira Bacteriostatic Water for Injection label on DailyMed includes a boxed warning against giving the product to neonates, meaning newborn babies. Newborn toxicity has been linked to benzyl alcohol. For fluid replacement or epidural or spinal anesthesia, the label says benzyl alcohol liquids must not be used.
If you give the water into a vein without a dissolved drug, it may cause hemolysis, which means red blood cells burst. Some medications do not mix well with benzyl alcohol; always ask a pharmacist about compatibility if you aren't sure.
Who should avoid using it?
Newborns must never receive medicines mixed with benzyl alcohol. For a newborn whose drug needs mixing with water, the label directs you to preservative-free Sterile Water for Injection instead. After 1 draw, this preservative-free single-dose vial is discarded.
The label says it is unknown whether this water can harm a fetus; pregnant women should receive it with additives only when clearly necessary. If a drug's package insert requests preservative-free water, you should avoid this product as well. A bacteriostatic water and sterile water comparison shows what sets the 2 vials apart.
Benzyl alcohol milligrams per dose
With a 0.9% strength, 9 mg of benzyl alcohol is contained in 1 full mL of water. For most subcutaneous draws, only a small fraction of 1 mL is used.
With a U-100 syringe, 10 units means 0.1 mL of liquid, which has 0.9 mg of benzyl alcohol. A draw of 20 units contains 0.2 mL of liquid and 1.8 mg; a draw of 50 units contains 0.5 mL and 4.5 mg.
Benzyl alcohol compared with rubbing alcohol
The benzyl alcohol in a mixing vial differs from household rubbing alcohol. The 2 liquids are separate products with completely different uses at your counter.
Use rubbing alcohol pads only to wipe the rubber vial stopper and clean your skin before injecting; let the skin dry before inserting the needle. You should never attempt to mix medication with rubbing alcohol.
Frequently asked questions
Is bac water with benzyl alcohol safe to inject?
The FDA-approved label allows Bacteriostatic Water for Injection to dilute or dissolve compatible drugs for injection in adults, while its warnings apply. This product is unsuitable for newborns, spinal procedures, fluid replacement and direct vein use without dissolved medication. Your prescriber or pharmacist can advise whether it suits your medication.
Is an allergy to bacteriostatic water possible for you?
The Hospira label facts we reference give no specific allergy rates or reactions linked to benzyl alcohol. Before mixing your vial, ask your pharmacist or prescriber if you have had past reactions to preservatives or injectable medications.
May I use bac water when preparing medicine for a baby?
For a newborn baby, never use bacteriostatic water. The boxed warning links benzyl alcohol to toxicity in neonates; preservative-free Sterile Water for Injection alone should be used to prepare newborn medications.