Benzyl alcohol

Last updated August 2026

The 0.9% preservative in bacteriostatic water. It’s what makes the water “bacteriostatic” — allowing a vial to be used for multiple doses over weeks rather than once.

At the 0.9% level found in bacteriostatic water, benzyl alcohol is what extends a reconstituted vial's usable window from a single draw to several weeks refrigerated. It is worth being aware of as a potential sensitivity for some people, and it is the reason sterile water, which lacks it, is treated as single-use. The preservative does not affect the concentration math, which depends only on peptide mass and total volume.

Educational reference only — not medical advice. Always follow the guidance of a qualified healthcare professional.