Why does bacteriostatic water contain benzyl alcohol?

Benzyl alcohol at 0.9% concentration acts as a bacteriostatic preservative — it stops bacteria from multiplying without needing refrigeration-grade sterility for every access. This allows researchers to draw from one reconstituted vial multiple times over a protocol while maintaining solution integrity.

Benzyl alcohol is an aromatic alcohol with well-documented bacteriostatic activity at low concentrations. At 0.9% — the concentration in USP Bacteriostatic Water for Injection — it inhibits the multiplication of most common bacterial contaminants introduced during repeated vial access, without chemically degrading the majority of peptide compounds. This preservative action is what distinguishes a multi-use reconstitution vehicle from single-use sterile water. The 0.9% concentration has been used in compendial preparations for decades, and its compatibility and stability characteristics are documented in pharmaceutical excipient literature.

Source: Pharm Dev Technol (2011) · PubMed

Bacteriostatic Water — 30mL, USP Grade purity →

Summarised from peer-reviewed literature for research reference. For laboratory research use only.