Does Bacteriostatic Water Need to Be Refrigerated? Shelf Life
Does bacteriostatic water need to be refrigerated? No. The labels specify controlled room temperature, 20 to 25 C (68 to 77 F), whether unopened or already punctured, and none directs refrigeration (Bacteriostatic Water for Injection, USP labels: Hospira, US MedSource and APP / Fresenius Kabi). Reconstituted drug storage follows the finished product label.
The storage table below covers bacteriostatic water before and after first puncture, three named reconstituted drug products, and the gap in research-peptide storage data. Four bacteriostatic water label listings support the water rows.1234 None of those water labels assigns a discard window after first entry,134 so the section on first puncture explains the separate USP 797 and CDC guidance. Named somatropin and glucagon labels provide the reconstituted drug examples.567
Education only: This page reports what manufacturer labels and published studies state about storage. It is general information, not medical advice, and it does not tell anyone what to take, how much to use, or how to prepare a dose. For the mixing math as a concept, see the peptide reconstitution calculator.
Does Bacteriostatic Water Need to Be Refrigerated Before It Is Opened?
No. Bacteriostatic water for injection is a sterile, nonpyrogenic water for injection sold in a multiple-dose vial, and the labels reached give one storage instruction for it: store at 20 to 25 C (68 to 77 F), USP Controlled Room Temperature.1 The same line appears on the Pfizer copy of the Hospira label,2 on the US MedSource label,3 and on the APP / Fresenius Kabi label,4 so Hospira, US MedSource and APP / Fresenius Kabi agree across four label listings, and none of them directs refrigeration of the sealed bottle.
None of these labels prints a protect from freezing or a protect from light instruction for the water itself either; the controlled room temperature line is the only storage directive on each.134 This page states no sealed-bottle shelf life.
What About After the First Puncture?
Puncturing the stopper does not change the storage temperature on the label, and it does not add a discard date either. The Hospira, US MedSource and APP / Fresenius Kabi labels designate the product a multiple-dose container from which repeated withdrawals may be made, and none of them prints a number of days or hours to discard after first entry.134
The widely repeated 28 day figure comes from somewhere else. It is the beyond-use date that USP General Chapter 797 and CDC injection guidance assign to opened multiple-dose vials in general, and both defer to the manufacturer. USP General Chapter 797 sets a beyond-use date of 28 days for an opened or entered multiple-dose container with antimicrobial preservatives, unless otherwise specified by the manufacturer,8 a limit the 2022 revision keeps,9 and CDC guidance likewise says an opened multi-dose vial should be dated and discarded within 28 days unless the manufacturer states another date.10 So the 28 days is a compounding and injection-safety rule for opened vials, not a number the bacteriostatic water label itself prints.
Bacteriostatic Water Storage at a Glance
The unopened bottle and the opened bottle sit at the same room temperature. What can change storage is reconstituting a product in the water: the finished product label then governs, and it differs by product, so that clock belongs to the finished product, not the diluent.
| Item and state | Store at | In-use window |
|---|---|---|
| Bacteriostatic water, unopened | Labels specify controlled room temperature, 20 to 25 C (68 to 77 F), with no refrigeration instruction (Bacteriostatic Water for Injection, USP labels: Hospira, US MedSource and APP / Fresenius Kabi). | This page states no sealed-bottle shelf life. |
| Bacteriostatic water, after first puncture | Labels specify the same 20 to 25 C (68 to 77 F), with no refrigeration instruction (Bacteriostatic Water for Injection, USP labels: Hospira, US MedSource and APP / Fresenius Kabi). | The bacteriostatic water label prints no discard window. USP 797 and CDC set 28 days as a compounding and injection-safety rule for opened multiple-dose vials unless the manufacturer states otherwise. |
| GENOTROPIN (somatropin), reconstituted | Label: stored refrigerated at 2 to 8 C (36 to 46 F), protected from light, not frozen (US FDA GENOTROPIN label). | Up to 28 days refrigerated; single-dose MINIQUICK up to 24 hours refrigerated before use (US FDA GENOTROPIN label). |
| HUMATROPE (somatropin), reconstituted | Label: stored refrigerated at 2 to 8 C (36 to 46 F), protected from light, freezing avoided (US FDA HUMATROPE label). | Up to 28 days refrigerated (US FDA HUMATROPE label). |
| Glucagon, reconstituted | Use immediately after mixing; no storage window on the label (US FDA Glucagon label). | Used immediately, any unused portion discarded (US FDA Glucagon label). |
| Research peptide, reconstituted | No general figure established in the sources. | No reconstituted temperature or in-use window is established for research peptides; the specific product label and a licensed pharmacist are the reference. |
Sources: Bacteriostatic Water for Injection, USP labels: Hospira, US MedSource and APP / Fresenius Kabi; USP General Chapter 797; CDC injection safety guidance; and the US FDA GENOTROPIN, HUMATROPE and Glucagon labels for the reconstituted pattern. A storage reference, not instructions for preparing anything.
What Changes Once a Peptide Is Reconstituted in It?
Everything above is about the water. The moment a lyophilized peptide or protein powder is dissolved in it, the storage question belongs to the finished product, and it becomes product specific: the FDA labels for named reconstituted drugs do not share one rule. Reconstituted somatropin is stored under refrigeration at 36 to 46 F (2 to 8 C), protected from light, for up to 28 days on both a somatropin pen and a somatropin cartridge,56 while reconstituted glucagon is used immediately and any unused portion discarded.7 Those somatropin labels also say not to freeze the reconstituted product,56 so refrigeration, light protection and a defined in-use window of up to 28 days describe the somatropin pattern, not a universal rule for every reconstituted drug.
These numbers belong to named drug labels, not to research peptides.
The refrigeration, light and window figures above are the FDA labels of somatropin and glucagon products. This page does not convert them into a storage figure for a reconstituted research peptide; for a specific product, its own label and a licensed pharmacist are the references. The glucagon label shows how far an in-use window can drop on reconstitution: the same glucagon powder may be stored up to 24 months at 20 to 25 C before it is mixed, then is used immediately once it is.7
For what these forms are and how they behave, see lyophilized peptides and reconstituted peptides.
Does Heat Change the Answer?
The water labels specify 20 to 25 C and do not report what happens outside that range, so they set no heat tolerance for the water either way. The Cochrane review covers human insulin storage, including pharmaceutical companies' data discussed for difficult living conditions.11 A separate study reports faster degradation at higher temperatures in solid-state human insulin, not a reconstituted solution.12 None of this sets a heat threshold for bacteriostatic water or for a research peptide mixed in it. Hot climate storage and what it means for a mixed vial is covered in our storing peptides in Vietnam heat guide.
Why It Is a Multiple-Dose Bottle: The Preservative
The preservative differs by labeler. Bacteriostatic water carries benzyl alcohol on the Hospira and US MedSource labels,13 while one labeler, APP / Fresenius Kabi, uses parabens instead for the same job,4 and a multiple-dose product is required to show antimicrobial effectiveness against a broad spectrum of microorganisms, which is why it carries a preservative at all.14 Benzyl alcohol is one of the two most common antimicrobial preservatives used in peptide and protein products.13
Bacteriostatic water carries a preservative and plain sterile water does not. See bacteriostatic water vs sterile water for the full breakdown.
Bottom Line
Supply partner: for bacteriostatic water, this page links to our supply partner, Peptara Labs. This page is education only; for storage and use, the product label and a licensed pharmacist are the references.
Disclosure: Some links on this page are referral links. Peptides Vietnam may earn a fee at no cost to you. Editorial content is never sold.
Frequently Asked Questions
Does bacteriostatic water need to be refrigerated?+
No. Every label reached stores bacteriostatic water for injection at controlled room temperature, 20 to 25 C (68 to 77 F), and none directs refrigeration, whether the vial is unopened or already opened (Bacteriostatic Water for Injection, USP labels: Hospira, US MedSource and APP / Fresenius Kabi). After a peptide or protein is reconstituted in it, storage is set by that finished drug label and differs by product: some reconstituted drugs are refrigerated, others are used immediately.
How should you store unopened bacteriostatic water?+
At controlled room temperature, 20 to 25 C (68 to 77 F). That single line is the only storage directive on the Hospira, US MedSource and APP / Fresenius Kabi labels, none of which adds a protect from freezing or protect from light instruction for the water, and none of which directs refrigeration. This page states no sealed-bottle shelf life (Bacteriostatic Water for Injection, USP labels: Hospira, US MedSource and APP / Fresenius Kabi).
How long is bacteriostatic water good for after you puncture the vial?+
The bacteriostatic water labels reached print no discard window after first entry; they designate the product a multiple-dose container only. USP General Chapter 797 sets a beyond-use date of 28 days for opened multiple-dose containers with antimicrobial preservatives unless the manufacturer specifies otherwise. CDC injection guidance likewise says opened multiple-dose vials should be dated and discarded within 28 days unless the manufacturer states another date. That 28 day figure is a compounding and injection-safety rule for opened multiple-dose vials, not a number printed on the bacteriostatic water label (USP General Chapter 797; CDC Preventing Unsafe Injection Practices, 2024).
Do you refrigerate a peptide once it is mixed with bacteriostatic water?+
Storage changes once a powder is reconstituted, and the pattern comes from FDA labels for named reconstituted drugs. Reconstituted somatropin cartridges are stored refrigerated at 36 to 46 F (2 to 8 C), protected from light, and not frozen; reconstituted glucagon is used immediately and any unused portion discarded (US FDA GENOTROPIN, HUMATROPE and Glucagon labels). These figures are the labels of named drug products, not a measurement of any research peptide, so this page gives no reconstituted storage figure for research peptides; a specific product label and a licensed pharmacist are the references.
Why does bacteriostatic water not need the fridge when other injectables do?+
The manufacturer labels specify controlled room temperature, 20 to 25 C, but the sources do not establish one cause for that storage requirement (Bacteriostatic Water for Injection, USP labels: Hospira, US MedSource and APP / Fresenius Kabi). Preservatives address microbial growth: multiple-dose products must show antimicrobial effectiveness against a broad spectrum of microorganisms (Pharmaceutics, 2023). The bacteriostatic water vs sterile water page linked below covers the reuse comparison.
Does heat damage bacteriostatic water or the peptide mixed in it?+
The manufacturer labels specify storage at 20 to 25 C and do not report what happens to the water outside that range, so they do not establish a heat tolerance for the water either way. The heat evidence cited on this page is human insulin, not any research peptide, so it sets no threshold for bacteriostatic water or another peptide; hot climate storage is covered in the storing peptides in Vietnam heat guide.
Can you freeze bacteriostatic water?+
No bacteriostatic water label reached prints a freeze or do not freeze instruction for the water; the only storage directive on each is the 20 to 25 C controlled room temperature line, so freezing is neither directed nor addressed by these labels (Bacteriostatic Water for Injection, USP labels: Hospira, US MedSource and APP / Fresenius Kabi). By contrast, the reconstituted somatropin labels do say not to freeze the mixed product (US FDA GENOTROPIN and HUMATROPE labels). The product label in front of you is the reference.
Last updated: September 29, 2026. Peptides Vietnam cites 14 evidence records for this page, all listed below.
Sources
- 1.US Food and Drug Administration via DailyMed. Bacteriostatic Water for Injection, USP (Hospira, Inc.), label revised 08/2019. States 0.9% (9 mg/mL) or 1.1% (11 mg/mL) benzyl alcohol added as a bacteriostatic preservative, supplied in a multiple-dose container, and Store at 20 to 25 C (68 to 77 F), USP Controlled Room Temperature.
- 2.Pfizer labeling (labeling.pfizer.com). Bacteriostatic Water for Injection, USP (Hospira labeling), revised 08/2019. Store at 20 to 25 C (68 to 77 F); supplied in a multiple-dose container for repeated withdrawals.
- 3.US Food and Drug Administration via DailyMed. Bacteriostatic Water for Injection, USP (US MedSource, LLC), revised 7/2014. Store at 20 to 25 C (68 to 77 F); supplied in a multiple-dose container.
- 4.Fresenius Kabi USA / APP Pharmaceuticals, LLC prescribing information. Sterile Water and Bacteriostatic Water for Injection, USP, revised July 2008. Bacteriostatic water contains 0.12% methylparaben and 0.012% propylparaben; Store at 20 to 25 C (68 to 77 F).
- 5.US Food and Drug Administration via DailyMed. GENOTROPIN (somatropin) for injection, prescribing information, Storage and Handling. After reconstitution, store under refrigeration at 36 F to 46 F (2 C to 8 C), protect from light, for up to 28 days; do not freeze; single-dose MINIQUICK may be refrigerated up to 24 hours before use.
- 6.US Food and Drug Administration via DailyMed. HUMATROPE (somatropin) prescribing information. Reconstituted cartridges are stable up to 28 days when refrigerated at 36 to 46 F (2 to 8 C); protect from light; avoid freezing the reconstituted cartridge.
- 7.US Food and Drug Administration via DailyMed. Glucagon Emergency Kit (glucagon for injection, lyophilized), prescribing information. Use reconstituted glucagon solution immediately and discard any unused portion; vials may be stored up to 24 months at 20 to 25 C (68 to 77 F) prior to reconstitution.
- 8.United States Pharmacopeia General Chapter 797, Pharmaceutical Compounding: Sterile Preparations (hosted chapter copy via SEFH). The beyond-use date for an opened or entered multiple-dose container with antimicrobial preservatives is 28 days, unless otherwise specified by the manufacturer.
- 9.Florida Department of Health, Board of Pharmacy. INV797, USP Sterile Compounding (Revision 1, USP 797 2022), August 2024. Multiple-dose preparations after initial entry are not used longer than the assigned beyond-use date or 28 days, whichever is shorter.
- 10.Centers for Disease Control and Prevention. Preventing Unsafe Injection Practices, page dated March 26, 2024. Once a multi-dose vial is opened it should be dated and discarded within 28 days unless the manufacturer states another date for that opened vial.
- 11.Richter B, Bongaerts B, Metzendorf MI. Thermal stability and storage of human insulin. Cochrane Database of Systematic Reviews, 2023. PMID 37930742. For difficult living conditions, pharmaceutical companies' data reported in the review indicate that unopened short-acting and intermediate-acting human insulin vials and cartridges can be stored at up to 25 C for a maximum of six months or up to 37 C for a maximum of two months without clinically relevant potency loss. Two studies reported up to 18% loss of insulin activity after one week to 28 days at 37 C. Novo Nordisk manufacturer data reported in the review put the loss of short-acting insulin activity at 37 C at 2.2 to 2.8 percent after one month, 5.7 percent after two months and 8.3 to 8.6 percent after three months, compared with baseline.
- 12.Fagan A, Bateman LM, O'Shea JP, Crean AM. Kinetics of human insulin degradation in the solid-state. Journal of Pharmaceutical Sciences, 2025. PMID 39725225. Temperature had a major impact on deamidation and covalent aggregation rates, with reaction rates increasing with temperature.
- 13.Meyer BK, Ni A, Hu B, Shi L. Antimicrobial preservative use in parenteral products: past and present. Journal of Pharmaceutical Sciences, 2007. PMID 17722087. Benzyl alcohol is among the two most common antimicrobial preservatives used in peptide and protein products.
- 14.Antimicrobial Preservatives for Protein and Peptide Formulations: An Overview. Pharmaceutics, 2023 (NCBI PMC10217790). Multi-dose drugs must show antimicrobial effectiveness against the growth of a broad spectrum of microorganism.