Quick answer: store every peptide or GLP-1 product exactly as its own label or pharmacy instructions say, because the limits differ by product and form. Typically, unopened brand-name GLP-1 pens and vials go in the refrigerator at 36–46°F (2–8°C), protected from light and never frozen, with a product-specific allowance for time at room temperature. Reconstituted or compounded vials are usually refrigerated and must be used by their beyond-use date (BUD).
A punctured multiple-dose vial of a manufactured product is generally good for 28 days unless its manufacturer says otherwise. When in doubt, the shorter date wins. This pillar guide covers how to read those rules, what the brand labels actually say, how BUDs work for compounded and reconstituted vials, and the signs that mean a vial should be discarded.
Educational only, not medical advice. This guide summarizes publicly available labeling and pharmacy standards. Your product's label and your pharmacist's instructions always take priority over anything here. Labels change, so check the insert that came with your medication.
The three dates on (or about) your vial
- Expiration date. Printed by the manufacturer; applies to the unopened product stored correctly.
- Beyond-use date (BUD). The date after which a compounded preparation, or an opened/punctured container, shouldn't be used. Pharmacies assign BUDs to compounded products, and an opened multi-dose vial has one from the moment it's first punctured.
- The room-temperature clock. Many brand labels allow a limited number of days out of the fridge. Once that clock starts, it usually can't be reset by putting the product back.
The Joint Commission's guidance on multi-dose vials puts it plainly: label an opened vial with the date it must be discarded, not just the date it was opened, and the BUD should never be later than the manufacturer's expiration date.
How long can brand-name GLP-1s stay out of the fridge?
Summarized from the US prescribing information and instructions for use. Check your own insert; presentations and labels change.
| Product | Before use | Room-temperature allowance | Don't |
|---|---|---|---|
| Zepbound (tirzepatide) single-dose pen or vial | Refrigerate 36–46°F (2–8°C) in the original carton | Up to 21 days at up to 86°F (30°C); don't return it to the fridge; discard if unused after 21 days | Freeze; use if frozen |
| Mounjaro (tirzepatide) single-dose pen or vial | Refrigerate 36–46°F (2–8°C) | Up to 21 days at up to 86°F (30°C) | Freeze |
| Ozempic (semaglutide) pen | Refrigerate 36–46°F before first use | After first use, 56 days at 59–86°F (15–30°C) or refrigerated | Freeze; store with needle attached |
| Wegovy (semaglutide) single-dose pen | Refrigerate 36–46°F | If needed, before removing the cap, 46–86°F (8–30°C) for up to 28 days | Freeze |
Newer presentations (for example, Zepbound's multi-dose vials and KwikPen) have their own in-use limits printed on their cartons. Use the rule for the exact product you have.
How long do compounded and reconstituted vials last?
Compounded GLP-1 and peptide vials don't have a brand label's storage table. Instead:
- The pharmacy assigns a BUD. It's based on the preparation's sterility category and any stability data, under the US Pharmacopeia's sterile-compounding standard, USP <797>. Use the date on the label.
- A multiple-dose compounded vial can't be used past its assigned BUD or 28 days after first puncture, whichever is shorter, under USP <797>.
- The FDA goes further for compounded GLP-1 vials. Its page on concerns with unapproved GLP-1 drugs recommends discarding a multiple-dose vial within 28 days after first use, even if medication remains, and even if the compounder's instructions say it can be used for longer, because contamination risk increases after 28 days.
- A conventionally manufactured multiple-dose container (such as a vial of bacteriostatic water) has a BUD of 28 days after first puncture unless the manufacturer specifies otherwise.
- A vial you reconstitute yourself should be used within the period given by its label, its supplier or your pharmacist. There's no universal number, and figures from forums or from a different product don't transfer. If nobody has given you one, ask.
Our post on the 28-day rule for mixed vials walks through which date applies to which vial and how to work out a discard date.
How long does reconstituted tirzepatide last? The honest answer is: as long as its label or pharmacy BUD says, and no longer than 28 days after first puncture for a multi-dose preparation. Brand-name Zepbound and Mounjaro don't need reconstituting at all; our tirzepatide vial guide covers the difference.
Do reconstituted peptides need to be refrigerated?
Generally, yes. Reconstituted peptides are usually stored refrigerated at 36–46°F (2–8°C), protected from light, unless the label says otherwise. Water in solution speeds up the chemical processes that break peptides down, which is why a reconstituted vial has a far shorter life than the dry powder.
Left out overnight? For brand-name products, the label's room-temperature allowance tells you whether it's still within limits (for example, a single-dose Zepbound pen kept at or below 86°F for under 21 days). For compounded or reconstituted vials, there's often no published allowance, so call the pharmacy rather than guessing.
Before mixing: storing lyophilized (freeze-dried) powder
Freeze-dried peptides are much more stable than solutions, but "stable" still depends on the product. Follow the label's storage temperature (some say refrigerate, some say freeze, some allow room temperature), keep the vial sealed and dry, and protect it from light and heat. Let a cold vial reach room temperature before opening if your instructions say so, to limit condensation. Our guide to storing peptides before you mix them compares real labels for freeze-dried products, and how to reconstitute peptides covers the mixing step.
Bacteriostatic water
- Unopened: store as its label says. The Bacteriostatic Water for Injection, USP label on DailyMed specifies controlled room temperature, 20–25°C (68–77°F).
- Opened: as a manufactured multiple-dose container, it falls under the 28-day rule after first puncture unless its manufacturer says otherwise. Write the discard date on the vial.
- It contains benzyl alcohol (0.9%, or 1.1% in some products, per its label) as a preservative, which is what allows multiple punctures. That doesn't make it immune to contamination; use a new sterile needle every time.
More detail is in does bacteriostatic water need to be refrigerated after opening?
Fridge practicalities
- Aim for 36–46°F (2–8°C). An inexpensive fridge thermometer tells you whether your fridge actually holds that range.
- Avoid the back wall and the area under the freezer vent, where some fridges run cold enough to freeze.
- Skip the door if your fridge's door shelves swing in temperature every time it opens.
- Keep products in their carton to protect them from light.
- Don't freeze anything whose label says not to, and don't use a product that has frozen. Most GLP-1 labels say to discard it.
When should you throw a vial away?
Don't use a product, and contact your pharmacist, if:
- It's past its expiration date, BUD or room-temperature limit.
- It has frozen, or been exposed to heat above its label limit. The FDA specifically recommends not using any injectable GLP-1 that arrives warm or with insufficient refrigeration after shipping.
- The solution looks cloudy, discolored or has particles, when it should be clear. The Zepbound label, for example, describes it as clear and colorless to slightly yellow and says not to use it if particles or discoloration are seen. See why a peptide can look cloudy after mixing.
- The stopper or seal is damaged, or you can't confirm it's been kept sterile.
- You can't tell how old it is.
A product can lose potency without looking any different, so appearance is a reason to discard, never a reason to keep. If a product doesn't seem to be working as expected, see our post on why a compounded GLP-1 can feel weaker.
Traveling with temperature-sensitive medication
Short version: keep it with you, keep it cool but not frozen, and know your product's room-temperature allowance. Our travel guide covers TSA rules, coolers and time zones.
Tracking it in Caliper
Caliper records each vial's reconstitution date and use-by date, plus the printed expiry, so you can see at a glance when a vial reaches its use-by date. Reminders can nudge you when a dose is due. Caliper only stores what you enter; it doesn't assign BUDs or judge whether a product is still good. That's your label and your pharmacist.
FAQ
How should I store peptides?
As the label says. Freeze-dried powder is typically kept sealed, dry and protected from light at the labeled temperature; reconstituted peptides are generally refrigerated at 36–46°F (2–8°C) and used by their beyond-use date.
Do reconstituted peptides need to be refrigerated?
Generally yes, unless the label says otherwise. Keep them at 36–46°F (2–8°C), protected from light, and don't freeze them.
How long does reconstituted tirzepatide last?
Use the beyond-use date on the pharmacy label. Under USP <797>, a multiple-dose compounded preparation can't be used past its assigned BUD or 28 days after first puncture, whichever comes first, and the FDA recommends discarding compounded GLP-1 multi-dose vials within 28 days of first use even if instructions say longer.
How long can Zepbound be out of the fridge?
The US label allows single-dose Zepbound pens and vials to be kept at room temperature up to 86°F (30°C) for up to 21 days. Once out, don't return it to the fridge; discard it after 21 days. Multi-dose presentations have their own limits on the carton.
How long can Ozempic be out of the fridge?
According to its label, after first use an Ozempic pen can be kept for 56 days at 59–86°F (15–30°C) or in the fridge.
Does bacteriostatic water need to be refrigerated?
Its label specifies controlled room temperature (20–25°C). Once punctured, it's generally discarded after 28 days unless its manufacturer says otherwise.
What is a beyond-use date?
The date after which a compounded preparation, or an opened container, shouldn't be used. Pharmacies assign it; it's printed on compounded labels.
Can I freeze peptides or GLP-1s?
Don't freeze a GLP-1 pen, a brand-name vial or a reconstituted solution; most labels say to discard it if frozen. Some freeze-dried powders are labeled for freezer storage before mixing. Follow the label.
My medication was left out overnight. Is it still OK?
For brand-name products, compare the time and temperature with the label's room-temperature allowance. For compounded or reconstituted vials, call your pharmacy.
The takeaway
Storage is label-specific. Fridge at 36–46°F, never frozen, out of the light is the common default; brand labels add a defined room-temperature allowance; compounded and reconstituted vials live and die by their BUD, with 28 days after first puncture as the ceiling for multi-dose vials. Write the discard date on every vial, and when a product's history is uncertain, ask before you use it.
Sources
- Zepbound (tirzepatide) US prescribing information and pen instructions for use, Eli Lilly
- Mounjaro (tirzepatide) medication guide, DailyMed
- Ozempic (semaglutide) prescribing information, Novo Nordisk
- Wegovy (semaglutide) prescribing information, Novo Nordisk
- FDA, FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss
- U.S. Pharmacopeia General Chapter <797>, as summarized in the Florida Department of Health's USP <797> (2022 revision) inspection guide
- The Joint Commission, Managing multi-dose vials
- DailyMed, Bacteriostatic Water for Injection, USP
Make the math (and the record-keeping) automatic
Caliper is a private, local-first tracker for GLP-1 and peptide protocols. You record the amount you took and it logs each dose with one tap, reminds you when the next one is due, tracks vials with reconstitution and use-by dates, and keeps injection sites, side effects and weight trends on one timeline. Your health data stays on your device, and Caliper never recommends or calculates a dose; it organizes what you and your provider decide.
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For adults 18+.
Medical disclaimer: This article is for general educational purposes only and is not medical advice. It does not recommend any dose, dilution, compound, product, supplier or protocol. Always follow your prescriber's instructions and the product label, and talk to a pharmacist or healthcare provider about any question regarding your medication, its preparation, storage, measurement or administration.