How to Store Peptides: Refrigeration, Shelf Life After Reconstitution, Travel

Key takeaways

• Yes: sermorelin, like nearly every compounded peptide, is stored at 2 to 8 degrees Celsius as a powder and as a mixed vial, in its carton, never frozen. The beyond-use date on the pharmacy label governs; 28 days after the first puncture is the ceiling for a vial mixed with bacteriostatic water, and a vial mixed with plain sterile water gets no such allowance.
• Not every peptide product is a refrigerator product. Egrifta WR (tesamorelin) is stored at room temperature before and after mixing and discarded 7 days after mixing. The label wins over any general rule, including ours.
• Brand GLP-1 pens carry precise label windows: a Wegovy pen may spend up to 28 days out of the refrigerator before use, Ozempic and Wegovy FlexTouch pens 56 days in use at room temperature, a Zepbound single-dose pen 21 days and a Zepbound multi-dose vial 30 days. A compounded vial has whatever its pharmacy wrote.
• Heat speeds chemical breakdown, light adds photo-degradation, and freezing can wreck a peptide invisibly. Insulin, the best-studied peptide drug, tolerates weeks at room temperature in the data; that is why labels can offer room-temperature windows, not a reason to skip the refrigerator.
• Travel in a carry-on with an insulated case and the pharmacy label, declare medically necessary liquids and syringes at the checkpoint, and discard anything cloudy, colored, frozen, overheated or undated.

The direct answer

Sermorelin needs to be refrigerated, before and after reconstitution: the powder at 2 to 8 degrees Celsius (36 to 46 Fahrenheit) in its carton, the mixed vial at the same temperature, upright and away from light, and neither ever frozen. How long the mixed vial lasts is decided by the beyond-use date the pharmacy printed on the label, which for a vial mixed with bacteriostatic water is at most 28 days after the first puncture, the convention the CDC attributes to USP General Chapter 797 for any opened multi-dose vial (CDC). A vial mixed with preservative-free sterile water is a single-use container by the same guidance and is not kept for later doses. The peptide dosage chart covers what goes in the syringe, the mixing compatibility chart covers why two vials should not meet in it, and how to reconstitute peptides covers the mixing itself.

Two things the direct answer hides. The 28-day figure describes the preservative, not the peptide: benzyl alcohol holds off bacterial growth for about that long once a stopper is punctured, while the peptide may lose potency sooner, which is why some pharmacies assign shorter dates and why the label beats the convention. And the refrigerator is not a universal rule. The Egrifta WR label stores the tesamorelin vial at 20 to 25 degrees Celsius before mixing, keeps the mixed vial at room temperature, forbids refrigerating or freezing it after mixing, and discards it 7 days after mixing (Egrifta WR label). The manufacturer measured that product's stability and wrote the rule from the data; a compounded vial has no such data, so its label is its only authority.

Storage rules by product type

Every GLP-1 label in the table says the same three things in different words: do not freeze, do not use if it has been frozen, and protect from light. Those are the rules worth carrying over to any compounded vial whose label is thin.

What heat, light and freezing do to a peptide

A peptide is a chain of amino acids folded into a shape, and both the chain and the shape can be damaged. Heat accelerates the chemical reactions that nick the chain (hydrolysis, oxidation of sensitive amino acids, deamidation) and loosens the fold until molecules unfold and stick together as aggregates. Light drives its own oxidation chemistry. Freezing concentrates everything dissolved in the vial as ice forms, exposes the peptide to ice surfaces and pH shifts, and can leave it aggregated after thawing. None of this is visible in a vial that still looks clear.

The best numbers come from insulin, a peptide hormone with decades of storage research. A 2023 Cochrane review found that unopened vials and cartridges of human insulin kept up to 25 degrees Celsius for six months, or up to 37 degrees for two months, lost no clinically relevant potency, and that prefilled syringes at 4 to 23 degrees for up to 28 days showed no relevant loss; two studies did record up to 18 percent loss after one week to 28 days at 37 degrees (Richter 2023). Room temperature for days is survivable for a well-formulated product, which is why the GLP-1 labels can allow 21 to 56 days out of the refrigerator; heat still costs potency at the temperatures a car or a windowsill reaches, which is why the labels cap the allowance at 30 degrees.

Light is the quieter risk. A 2025 analysis of liraglutide, a GLP-1 peptide, under heat and light stress identified ten degradation products, four never reported before (Badgujar 2025); the Wegovy label's instruction to keep the pen in its carton and discard one exposed to light is the practical version. Keep vials in the carton or a closed box inside the refrigerator.

Freezing has no safe margin. Every label in the table says do not use a product that has been frozen, and domestic refrigerators freeze things more often than people expect: the back wall and the shelf nearest the cooling element can drop below zero while the door reads 4 degrees. A vial that froze and thawed overnight can look perfect and be inactive. The remedy is a middle shelf away from the back and, if the appliance is unreliable, a thermometer.

Dry powder is more forgiving than solution, which is why peptides ship lyophilized and why a carton that arrives cool rather than cold is usually fine. Once water is added, the clock starts, and the beyond-use date is the only measurement of it you have.

Travel

The two problems on a trip are temperature and paperwork, and both are solved before you leave.

• Carry-on only, in an insulated case with a cold pack that does not touch the vials. Checked holds are not temperature controlled, and a frozen pack against a glass vial is a freezing risk, not a refrigeration method.
• The label travels with the medication. TSA permits medically necessary liquids in reasonable quantities beyond the 3.4-ounce limit and unused syringes that accompany injectable medication; both must be declared at the checkpoint, and TSA recommends that medications be labeled (TSA). A pharmacy label with your name, the drug and the concentration makes that conversation short; an unlabeled research vial with a bag of syringes is a different conversation.
• Use the label windows. A brand GLP-1 pen's room-temperature allowance may cover a whole trip; a compounded vial has no published window, so keep it cold and ask the pharmacy before you go.
• Hotel refrigerators are often too warm, or too cold at the back. Put the vial in the middle, away from the cooling plate, and check the thermostat; a refrigerator thermometer settles the question.

Signs a vial should be discarded

• The solution is cloudy, has visible particles, or has changed color. The labels for the brand products are explicit: Zepbound must be colorless to slightly yellow with no particles, and Egrifta WR is not to be used if the solution is cloudy, colored or contains solid particles.
• It froze, or you cannot be sure it did not.
• It sat warm for days, or anywhere above 30 degrees Celsius for any length of time.
• It is past the beyond-use date on the pharmacy label, or past 28 days from the first puncture of a bacteriostatic-water vial, whichever comes first.
• It has no date on it. A vial you cannot date is a vial you cannot trust.
• The stopper is damaged, or the vial has been entered with a needle that was used on someone else or on another vial.

A clear solution is necessary, not sufficient: potency loss has no appearance, and the only things standing between you and an inactive or contaminated dose are the date on the label and the temperature the vial has lived at. When in doubt, call the dispensing pharmacy.

Bottom line

Refrigerate sermorelin and every other compounded peptide vial at 2 to 8 degrees Celsius, powder and solution alike, in the carton and away from the back wall, and use the mixed vial by the beyond-use date, never later than 28 days after the first puncture when bacteriostatic water was used. Read the label on anything with a brand name, because the manufacturer may have earned a different rule. Treat heat and light as slow damage and freezing as sudden damage, travel with the cold chain and the label in your carry-on, and discard a vial on appearance, history or date without arguing with it.

Frequently asked questions

+−Does sermorelin need to be refrigerated?

Yes. Compounded sermorelin is dispensed with refrigeration instructions for both the lyophilized powder and the reconstituted vial: 2 to 8 degrees Celsius (36 to 46 Fahrenheit), in the carton, never frozen. Brief room-temperature exposure in transit is normal; days on a counter are not. The beyond-use date on your pharmacy label says how long the mixed vial lasts, and 28 days after the first puncture is the ceiling for a vial mixed with bacteriostatic water.

+−How long does sermorelin last after reconstitution?

Until the beyond-use date on the pharmacy label, which is usually two to four weeks for a vial mixed with bacteriostatic water and kept refrigerated. The 28-day figure comes from the CDC and USP convention for opened multi-dose vials; it describes the preservative, not the peptide, and a pharmacy may assign a shorter date. A vial mixed with plain sterile water has no preservative and does not get 28 days.

+−Does compounded semaglutide expire after 28 days?

It expires on the beyond-use date printed on the pharmacy label, which is commonly 28 days after the vial is first punctured, because compounded semaglutide is a preserved multi-dose solution. The brand products have their own label rules: an Ozempic pen in use is good for 56 days, a Wegovy FlexTouch pen for 56 days after first use, and an opened Zepbound multi-dose vial for 30 days or four weekly doses, whichever comes first.

+−How long can compounded semaglutide be unrefrigerated?

There is no published room-temperature allowance for compounded semaglutide; the pharmacy that made it sets the beyond-use date and the storage conditions, and most label it refrigerated. For scale, the manufacturer's data allow an unopened Wegovy pen up to 28 days at 8 to 30 degrees Celsius, and an Ozempic pen in use 56 days at up to 30 degrees. A compounded vial left out overnight is a question for the pharmacy, not a guess.

+−Can I freeze peptides to make them last longer?

No. Every GLP-1 label says do not freeze and do not use if frozen, and the same applies to reconstituted peptide vials: freezing concentrates the solutes and forms ice crystals that can unfold and clump a peptide, and the damage is not visible. Do not store any vial against the back wall or the cooling element of a refrigerator, where it can freeze without you noticing.

+−Does bacteriostatic water need to be refrigerated?

No. The label on bacteriostatic water for injection says to store it at 20 to 25 degrees Celsius (68 to 77 Fahrenheit). Once a vial is in use, date it and treat it like any opened multi-dose vial: the Egrifta WR label, for example, tells patients to discard the bacteriostatic water 28 days after first use.

+−How do I travel with peptides on a plane?

Keep everything in your carry-on, in an insulated case with a cold pack that does not touch the vials, together with the pharmacy label. TSA allows medically necessary liquids in reasonable quantities above the usual 3.4-ounce limit and allows unused syringes when they accompany injectable medication; declare them at the checkpoint for inspection. Checked baggage is not temperature controlled.

+−How do I know if a peptide vial has gone bad?

Discard it if the solution is cloudy, colored or has particles, if it was frozen, if it sat warm for days, if it is past the beyond-use date, or if you cannot say when it was mixed. Potency loss is invisible, so a clear solution past its date is not a safe vial; call the dispensing pharmacy before using anything you are unsure about.

Sources

1. GuidelineCDC. Injection safety: clinical safety guidance for healthcare providers (single-dose vials, multi-dose vials, 28-day rule). Reviewed March 2024. (2024)
2. LabelHospira, Inc. Bacteriostatic Water for Injection, USP, multiple-dose vial. Prescribing information, revised August 2019 (DailyMed). (2019)
3. LabelNovo Nordisk. Wegovy (semaglutide) injection and tablets: prescribing information, revised June 2026 (DailyMed setid ee06186f-2aa3-4990-a760-757579d8f77b). (2026)
4. LabelEli Lilly. Zepbound (tirzepatide) injection, for subcutaneous use: prescribing information, revised August 2026 (DailyMed). (2026)
5. LabelNovo Nordisk. Ozempic (semaglutide) injection: prescribing information, revised June 2026 (DailyMed setid adec4fd2-6858-4c99-91d4-531f5f2a2d79). (2026)
6. LabelTheratechnologies. EGRIFTA WR (tesamorelin) for injection, 11.6 mg per vial: full prescribing information, revised March 2025. DailyMed. (2025)
7. ReviewRichter B, Bongaerts B, Metzendorf MI. Thermal stability and storage of human insulin. Cochrane Database Syst Rev 2023;11:CD015385. (2023)
8. StudyBadgujar D et al. Assessment of thermal and photolytic stress effects on the stability of primary structure of synthetic liraglutide using LC-HRMS/MS. J Pept Sci 2025;31:e70050. (2025)
9. RegulatoryTransportation Security Administration. What can I bring? Medications (liquid); unused syringes (medically necessary liquids in reasonable quantities and syringes accompanying injectable medication must be declared at the checkpoint).