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September 2026

Bacteriostatic Water for Peptides: What It Is and Who Pays for It

Bacteriostatic water is sterile water with benzyl alcohol, sold in multiple-dose vials for mixing injectable drugs. Its label sets hard limits, and a peptide plan's price may or may not include it.

ByDerek MossPricing analystPublished

A month of sermorelin typically costs $185. That is the median across 137 sellers that publish a monthly price. That figure is the plan. It says nothing about the water you mix it with.

Some injectable peptides ship as a dry powder. The powder needs a liquid before it can be drawn into a syringe. When that liquid is bacteriostatic water, its own label sets rules. This page covers what it is, what its label allows, and where its cost hides.

What bacteriostatic water is

It is sterile water for injection with a preservative added [1]. The preservative is benzyl alcohol. The label lists two strengths. One is 0.9%, or 9 mg per mL. The other is 1.1%, or 11 mg per mL [1].

The benzyl alcohol is the point. It lets the vial take repeated needle withdrawals. The label calls it a multiple-dose container for exactly that reason [1].

The label does not describe it as a treatment. It is “indicated only for diluting or dissolving drugs” for intravenous, intramuscular or subcutaneous injection [1]. It is also marked “Rx only” [1].

What the label says it is not for

Uses the bacteriostatic water label rules out
UseWhat the label states
NewbornsMust not be used, due to benzyl alcohol toxicity
Fluid replacementShould not be used
Epidural or spinal anesthesiaShould not be used
IV injection on its ownMay cause hemolysis without a solute
Storing a mixed drugNot unless the drug's maker directs it
Uses the bacteriostatic water label rules out. Bacteriostatic Water for Injection, USP, prescribing label

How much water goes in a vial

There is no single answer, and the label says so. The volume depends on the concentration, dose and route the drug's maker recommends [1].

For a compounded peptide, that instruction comes from the pharmacy that filled it. It belongs on the vial label or the pharmacy's insert. If it is missing, ask the pharmacy before you mix.

The arithmetic is simple. Concentration is the powder's milligrams divided by the milliliters added. Double the water and each milliliter holds half as much drug. The guide to peptide needles and syringes explains how that volume reads on a syringe barrel.

The 28-day clock on an opened vial

CDC's rule for clinicians is plain. Date it when the needle first goes in. Discard it within 28 days, unless the manufacturer sets a different date [2]. The date may never run past the printed expiration [2].

Manufacturers do set their own dates. Zepbound, a brand of tirzepatide, comes in a multi-dose vial. Its label says to discard it 30 days after first use, or after four weekly doses [4]. The label on the vial in your hand wins.

Unopened bacteriostatic water stores at 20 to 25°C, which is ordinary room temperature [1]. The peptide it is mixed into usually has stricter rules. Those are in how to store peptides.

Who pays for the supplies

This site records each seller's monthly plan price. It holds no prices for diluent, syringes or swabs. So no supply figure appears here.

The plan figures are real, though. A month of NAD+ typically costs $191.25 across 161 sellers. The range runs from $60 to $349, read through September 2026.

Sermorelin plans run from $99 to $349 a month. None of those figures says whether water and syringes are in the box.

Brand labels show that supplies are often left out. The Zepbound vial instructions say the needle and syringe are not included [4]. The Vyleesi carton leaves out alcohol wipes, gauze and bandages [3].

A compounded plan may bundle supplies, or it may not. Two plans with the same headline can cost different amounts once supplies are counted. Compare them on the same basis.

One question settles it before you pay. Does the monthly price include the diluent, the syringes and a sharps container? Get the answer in writing. Then compare the plans on the price boards.

Products labeled for research are a separate matter. See what research use only means before buying anything labeled that way.

FAQ

5 questions

What is bacteriostatic water used for with peptides?

It is the liquid used to dissolve a powdered peptide before injection. Its label limits it to diluting or dissolving drugs for injection.

How much bacteriostatic water do you add to a peptide vial?

The label says the volume depends on the concentration, dose and route the drug's maker recommends. For a compounded peptide, the pharmacy's instructions set it.

How long does an opened vial of bacteriostatic water last?

CDC's default for an opened multiple-dose vial is to date it and discard it within 28 days, unless the manufacturer sets a different date.

Is bacteriostatic water the same as sterile water?

No. Bacteriostatic water contains benzyl alcohol as a preservative. Its label says only preservative-free sterile water should be used for newborns.

Does a peptide plan include bacteriostatic water and syringes?

Sometimes. This site records plan prices only, and brand labels such as Zepbound's vial state that the needle and syringe are not included. Ask the seller before paying.

Sources

4 cited
  1. [1]Hospira, Inc. (2026). Bacteriostatic Water for Injection, USP (multiple-dose vial) — label DailyMed, U.S. National Library of Medicine. Source
  2. [2]Centers for Disease Control and Prevention (2024). Preventing Unsafe Injection Practices CDC, Injection Safety. Source
  3. [3]Cosette Pharmaceuticals, Inc. (2025). VYLEESI (bremelanotide) injection — prescribing information and instructions for use DailyMed, U.S. National Library of Medicine. Source
  4. [4]Eli Lilly and Company (2026). ZEPBOUND (tirzepatide) injection — prescribing information and instructions for use DailyMed, U.S. National Library of Medicine. Source