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Terminus Peptides
  • Research use only — not for human or veterinary use
  • 55 compound profiles, every source cited
  • 62 research materials listed
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  • Vials and pre-filled pens
  • Dispatched and supported from the UK
  • Every profile states its UK regulatory status

Research profile · Research reagent

Bacteriostatic water

Also known as Bacteriostatic water for injection

Clinical — evidence level 4 of 4: Established clinical evidencePrescription only — UK regulatory status: Prescription-only medicine (UK)

Overview

Water with a preservative added. A UK-authorised product of this name exists and is prescription only.

Category
Research reagent
Highest evidence level identified
Established clinical evidence
Last scientifically reviewed
20 August 2026
Last regulatory review
20 August 2026

Mechanism under investigation

Bacteriostatic water for injection is water for injections with an antimicrobial preservative added, allowing a container to resist microbial growth. The UK-authorised product states its composition as 9.45 mg per millilitre of benzyl alcohol. It has no pharmacological action of its own — the UK product information records the indications, pharmacodynamic properties and undesirable effects sections as none or none stated.

Research areas

  • Laboratory preparation

These are fields in which the compound has been investigated. Listing a field is not a statement that anything was demonstrated within it.

Current evidence

In-vitro evidence

Cells, tissues or biochemical systems outside a living organism.

No efficacy literature, and none would be expected. The relevant standard is pharmacopoeial preservative-effectiveness testing rather than published study.

Animal evidence

Studies in living non-human animals.

Absent for the product. The authorised product information states there are no preclinical data of additional relevance. Benzyl alcohol itself has a separate toxicology literature.

Human observational evidence

Studies observing people without assigning an intervention.

No efficacy data. The substantive human literature concerns harm from the preservative rather than benefit from the product — neonatal case series describing the condition known as gasping syndrome, and later audits of excipient exposure in intensive care.

Clinical-trial evidence

Studies assigning an intervention to human participants.

None. No trial has been run on the diluent as an intervention, and none would be expected.

Study limitations

  • The evidence level recorded reflects long-standing authorised pharmaceutical use as a diluent, not therapeutic efficacy — of which there is none claimed and none demonstrated.
  • The UK authorisation is specific to one product and one indication. It does not make bacteriostatic water generically a licensed UK diluent, and the authorised presentation is a single one-millilitre pre-filled syringe rather than a multi-dose vial as sold in the United States.
  • The UK and United States articles are not identical: 9.45 mg per millilitre of benzyl alcohol against 0.9 or 1.1 per cent, and the United States label explicitly describes a multiple-dose container.
  • Vials sold in the UK as research-use-only bacteriostatic water are not the authorised product and carry no regulatory assessment of sterility, preservative content or quality.
  • There is no efficacy evidence base to appraise, so conventional evidence grading does not meaningfully apply to this entry.

UK regulatory context

Prescription-only medicine (UK)

A medicine that may lawfully be supplied in the UK only against a prescription from an appropriate practitioner.

Source: Bacteriostatic Water for Injection — Summary of Product Characteristics (opens medicines.org.uk in a new tab) (electronic Medicines Compendium)

Regulatory classification is jurisdiction-specific. A compound authorised elsewhere is not thereby authorised in the UK, and a supplier’s description of a substance does not determine how it is classified in law. See safety and regulation for the framework and the authoritative sources.

Safety and interpretation

The identified hazard is benzyl alcohol, not water. The UK product information contraindicates the product in hypersensitivity to benzyl alcohol and warns that intravenous benzyl alcohol has been associated with serious adverse events and death in paediatric patients including newborns, that the minimum amount at which toxicity may occur is not known, and that premature and low-birth-weight infants may be more susceptible. It further warns that the combined daily load from all sources must be considered in liver or kidney impairment, and in pregnancy and breastfeeding, because of accumulation and metabolic acidosis. The United States label is blunter still, directing that only preservative-free sterile water be used where water is required for preparing medicines for newborns. Benzyl alcohol may also cause hypersensitivity reactions.

References