Quick answer: store an unmixed (freeze-dried, or "lyophilized") vial exactly as its label says, because the right temperature differs by product: some FDA-approved freeze-dried products are labeled for room temperature, others for the refrigerator, and a few change rules once they're dispensed. Whatever the temperature, keep the vial sealed, dry, in its carton and out of light and heat, and don't freeze it unless the label says you can. Research-use vials don't come with FDA-reviewed storage data, so follow the vial's own label and ask a pharmacist if it doesn't give one.
Educational only, not medical advice. This article explains how to read storage instructions. It doesn't recommend any compound, dose or source, and it isn't a substitute for your product's label or your pharmacist's advice.
Why there's no single rule
Dry powder is generally far more stable than the same drug once it's dissolved, which is why mixed vials have much shorter use-by dates. But "more stable" still depends on the molecule and the formulation, and the labels show it. Two FDA-approved peptide products that are supplied as freeze-dried powder:
| Product | Storage before mixing, per its US label |
|---|---|
| EGRIFTA SV (tesamorelin), 2 mg vial | "Store EGRIFTA SV 2 mg vial at room temperature at 20°C to 25°C (68°F to 77°F)," protected from light by keeping it in the original box |
| GATTEX (teduglutide), 5 mg vial | "Prior to Dispensing: Store ... refrigerated at 2°C to 8°C (36°F to 46°F). Do not freeze." After dispensing: "Store ... at room temperature up to 25°C (77°F). Do not freeze," with a 90-day "use by" date |
Same kind of product (a freeze-dried peptide in a vial), two different answers, and one of them changes once the pharmacy hands it over. That's why the label on your vial beats any general rule, including the one in a forum thread.
Brand-name GLP-1s such as Zepbound, Mounjaro, Ozempic and Wegovy aren't powders at all; they come as ready-to-use solutions with their own storage tables. Our storage guide covers those.
Fridge, freezer or closet?
- Room temperature (a closet or drawer): only if the label allows it. "Room temperature" on US labels usually means controlled room temperature, 20–25°C (68–77°F). A hot closet, a car or a sunny windowsill is not that.
- Refrigerator: 36–46°F (2–8°C) if the label says to refrigerate. Keep the vial in its carton, away from the back wall and the freezer vent where some fridges run cold enough to freeze.
- Freezer: only if the label specifically lists freezer storage for the unmixed vial. Some FDA-approved labels for freeze-dried products, including GATTEX's, say "Do not freeze." Never freeze a vial once it's mixed unless its label says you can.
If the label gives no storage instruction at all, that's a question for a pharmacist, not a guess.
What's true for every unmixed vial
- Keep it sealed. Don't open or puncture a vial until you're ready to mix it.
- Keep it dry. Moisture is the enemy of a freeze-dried powder. Store it in its carton, and avoid humid places such as a bathroom cabinet.
- Keep it dark. Labels routinely say to keep vials in the original carton to protect them from light.
- Keep it away from heat. Don't leave vials in a car, next to a stove or in a mailbox. The FDA recommends not using any injectable GLP-1 that arrives warm or with insufficient refrigeration, and the same caution makes sense for any temperature-sensitive delivery.
- Let a cold vial reach room temperature before opening it if your instructions say so; this limits condensation inside the vial.
- Check the expiration date and don't use a vial past it.
Research-use vials
Vials sold as "research use only" are not FDA-approved products, and nobody has reviewed their identity, purity, sterility or stability. That has a practical consequence for storage: there's no FDA-reviewed data on how long the powder lasts at any temperature. Follow the storage line on the vial label, keep the vial away from heat and light, and write the date on it when you mix it. A certificate of analysis can tell you what a lab found in one batch at one point in time, not how it has been stored since.
After you mix it
Once you add diluent, the storage rules change, usually to refrigeration and a much shorter use-by date. Our reconstitution guide covers mixing, the 28-day rule for mixed vials covers how long a punctured vial can be used, and does bacteriostatic water need to be refrigerated? covers the diluent.
Signs an unmixed vial shouldn't be used
- It's past its expiration date.
- It was frozen, or exposed to heat, when its label says not to be.
- The seal or stopper is damaged, or the vial is cracked.
- The powder looks wet, collapsed, discolored or stuck to the glass differently from what you expect, or you can't tell how old it is.
When in doubt, ask your pharmacist before you mix it.
Tracking it in Caliper
Caliper's vial and inventory tracking records each vial's printed expiry, and once you mix it, its reconstitution date and use-by date. That way you can see which unmixed vials expire first and use those first. Caliper stores the dates you enter; it doesn't judge whether a product is still good. That's your label and your pharmacist.
FAQ
How should I store peptides before reconstitution?
Exactly as the label says. Some freeze-dried products are labeled for room temperature, others for the refrigerator. In every case keep the vial sealed, dry, in its carton and away from light and heat.
Do unmixed peptides need to be refrigerated?
It depends on the product. EGRIFTA SV's label says room temperature; GATTEX's says refrigerate before dispensing and room temperature after. Research-use vials have no FDA-reviewed storage data, so follow the vial label and ask a pharmacist if it's missing.
Can I freeze peptides before mixing them?
Only if the label specifically allows freezer storage for the unmixed vial. Some FDA-approved labels for freeze-dried products, such as GATTEX's, say "Do not freeze." Never freeze a mixed vial unless its label says you can.
Can I keep unmixed peptide vials in a closet?
Only if the label allows room-temperature storage, which on US labels usually means 20–25°C (68–77°F), and only if the spot stays dry, dark and away from heat.
My vial arrived warm. Is it OK?
The FDA recommends not using any injectable GLP-1 that arrives warm or with insufficient refrigeration. For other products, compare the conditions with the label and ask your pharmacist before using it.
How long does peptide powder last before mixing?
Until the expiration date on the label, if it's been stored as labeled. Research-use vials have no FDA-reviewed stability data.
The takeaway
The label picks the temperature; you keep it sealed, dry, dark and cool. Freeze-dried products disagree with each other about fridge versus room temperature, so read yours. Don't freeze anything the label doesn't say to freeze, and once you mix it, a new set of rules starts.
Sources
- DailyMed, EGRIFTA SV (tesamorelin) prescribing information
- DailyMed, GATTEX (teduglutide) prescribing information
- FDA, FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss
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.
Start tracking your vials and doses with Caliper →
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.