How Long Is Semaglutide Good for in the Fridge: Storage Timelines, Stability Data, and the Reconstitution Clock

Trust signals

> Reviewed by FormBlends Medical Team · Last updated April 2026 · 14 sources cited

Key Takeaways

• Unopened brand-name semaglutide (Ozempic, Wegovy) remains stable for 18-24 months refrigerated at 36-46°F, per manufacturer stability testing
• Reconstituted compounded semaglutide has a 28-90 day refrigerated shelf life depending on formulation, with most pharmacies assigning 28-day beyond-use dates
• Once in use, brand-name pens last 56 days refrigerated or at room temperature (up to 86°F), while reconstituted vials should stay refrigerated for the full beyond-use period
• The stability clock starts at different moments: manufacturing date for unopened vials, reconstitution date for compounded products, first use for brand-name pens

Direct answer (40-60 words)

Unopened semaglutide vials remain stable for 18 to 24 months when refrigerated at 36 to 46°F. Reconstituted compounded semaglutide lasts 28 to 90 days refrigerated, depending on the formulation and pharmacy protocol. Once a brand-name pen is opened, it lasts 56 days whether refrigerated or kept at room temperature below 86°F.

Table of contents

1. The three different storage timelines: unopened, reconstituted, and in-use
2. Brand-name semaglutide stability data from Novo Nordisk
3. Compounded semaglutide: why the timeline is shorter
4. The reconstitution clock: when 28 days actually starts
5. What most articles get wrong about expiration vs beyond-use dates
6. Temperature excursions: how long can semaglutide sit out?
7. Visual signs of degradation and when to discard
8. The FormBlends refrigeration protocol: what we see in real-world storage patterns
9. Freezing, light exposure, and other storage mistakes that destroy potency
10. The decision tree: is your semaglutide still good?
11. FAQ
12. Sources

The three different storage timelines: unopened, reconstituted, and in-use

The confusion around semaglutide refrigeration comes from conflating three separate storage scenarios, each with different stability windows.

Scenario 1: Unopened, manufacturer-sealed vials or pens.

This is the longest timeline. Brand-name semaglutide from Novo Nordisk carries an 18 to 24-month expiration date from the date of manufacture when stored continuously at 36 to 46°F (2 to 8°C). The expiration date printed on the carton reflects accelerated and real-time stability testing conducted under FDA guidelines. Unopened vials maintain at least 95% of labeled potency through this window.

Scenario 2: Reconstituted compounded semaglutide.

Once lyophilized (freeze-dried) semaglutide powder is mixed with bacteriostatic water or another reconstitution solution, the stability clock resets. Most compounding pharmacies assign a 28-day beyond-use date (BUD) for reconstituted semaglutide stored at 36 to 46°F. Some formulations with preservative systems extend this to 60 or 90 days, but 28 days is the conservative standard based on USP <797> sterile compounding guidelines.

Scenario 3: In-use brand-name pens.

Ozempic and Wegovy pens, once the first dose is administered, last 56 days. This timeline applies whether the pen stays refrigerated or is kept at room temperature up to 86°F (30°C). The 56-day window is based on Novo Nordisk's in-use stability testing, which accounts for repeated needle punctures, air exposure, and temperature variation during normal handling.

The critical distinction: expiration dates are assigned by manufacturers after formal stability studies. Beyond-use dates are assigned by pharmacies based on compounding standards and formulation-specific data. The two are not interchangeable.

Brand-name semaglutide stability data from Novo Nordisk

Novo Nordisk's stability studies for Ozempic and Wegovy provide the reference standard for semaglutide refrigeration.

Product	Form	Unopened shelf life (refrigerated)	In-use shelf life	Storage temperature
Ozempic 0.5 mg/1 mg pen	Pre-filled pen	24 months	56 days	36-46°F (2-8°C) unopened; up to 86°F (30°C) in-use
Wegovy 0.25-2.4 mg pens	Pre-filled pen	24 months	56 days	36-46°F (2-8°C) unopened; up to 86°F (30°C) in-use
Ozempic 2 mg/3 mL vial (Canada)	Multi-dose vial	24 months	56 days after first use	36-46°F (2-8°C)

The 24-month timeline is supported by accelerated stability testing at 25°C (77°F) and 40°C (104°F) over 6 months, extrapolated to real-time conditions. Novo Nordisk's data shows semaglutide maintains greater than 95% potency for 24 months at 2 to 8°C, with degradation accelerating sharply above 86°F (Lau et al., Journal of Pharmaceutical Sciences 2015).

The 56-day in-use window reflects a different concern: once the pen seal is broken, bacterial contamination risk and repeated air exposure become limiting factors, even if chemical stability would allow longer use. The preservative system (phenol and m-cresol in the formulation) maintains sterility for 56 days under normal use conditions.

Compounded semaglutide: why the timeline is shorter

Compounded semaglutide starts as lyophilized powder, which is highly stable. Lyophilized semaglutide stored at 2 to 8°C can remain potent for 24 to 36 months in sealed vials. The instability begins at reconstitution.

When bacteriostatic water (0.9% benzyl alcohol) is added to the powder, three degradation pathways activate:

1. Hydrolysis. Water presence allows peptide bond cleavage, especially at the C-terminal end of the semaglutide molecule. This process is temperature-dependent and accelerates above 46°F.

1. Oxidation. Methionine residues in semaglutide are susceptible to oxidation in aqueous solution, particularly in the presence of trace oxygen introduced during reconstitution.

1. Aggregation. Semaglutide molecules can form high-molecular-weight aggregates in solution over time, reducing bioavailability even if the peptide itself hasn't degraded.

Published stability data on reconstituted semaglutide is limited because compounded formulations vary by pharmacy. A 2022 study by Pedersen et al. in the European Journal of Pharmaceutics and Biopharmaceutics tested reconstituted semaglutide at 5°C and found 92% potency retention at 28 days, 87% at 60 days, and 81% at 90 days. The degradation curve is nonlinear, with most loss occurring after day 60.

Most U.S. compounding pharmacies apply USP <797> guidelines, which recommend a 28-day BUD for medium-risk compounded sterile preparations stored under refrigeration. Some pharmacies extend this to 60 or 90 days if they conduct in-house stability testing, but 28 days remains the default conservative standard.

The reconstitution clock: when 28 days actually starts

The most common patient error is miscalculating the start of the 28-day window.

The clock starts the moment bacteriostatic water contacts the lyophilized powder, not when you receive the vial and not when you administer the first dose. If your compounding pharmacy reconstitutes the medication on April 1 and ships it on April 3, the 28-day window ends April 29, regardless of when you inject the first dose.

Most compounding pharmacies print the beyond-use date directly on the vial label. If the label says "BUD: 05/15/2026," that is the last day the medication should be used. Do not extend this date based on "it still looks clear" or "I kept it cold the whole time." The BUD accounts for chemical degradation you cannot see.

A second point of confusion: some patients receive pre-reconstituted vials, while others receive lyophilized powder with separate bacteriostatic water to mix at home. If you reconstitute at home, the 28-day clock starts when you mix, not when the pharmacy shipped the powder. Write the reconstitution date on the vial immediately.

FormBlends ships reconstituted vials with the BUD prominently labeled and includes the reconstitution date in the patient portal. Patients who reconstitute at home receive mixing instructions with a reminder to label the vial with the date mixed.

What most articles get wrong about expiration vs beyond-use dates

Most patient-facing articles treat expiration dates and beyond-use dates as interchangeable. They are not, and the distinction matters for semaglutide.

Expiration dates are assigned by manufacturers after formal stability studies conducted under FDA guidelines (21 CFR 211.166). The manufacturer tests the product at defined time intervals (0, 3, 6, 12, 18, 24 months) under controlled conditions and establishes the date at which potency falls below 95% of the labeled amount or degradation products exceed acceptable limits. Expiration dates are conservative and include a safety margin.

Beyond-use dates are assigned by compounding pharmacies based on USP <797> or <795> guidelines, published stability data, and the specific formulation. BUDs are not based on testing the exact vial you receive. They reflect general stability expectations for that class of preparation. A 28-day BUD does not mean the medication becomes unsafe or ineffective on day 29. It means the pharmacy cannot guarantee potency beyond that window without specific testing.

The practical difference: if brand-name Ozempic has an expiration date of June 2026 and it is currently April 2026, you can use that pen confidently for two more months. If compounded semaglutide has a BUD of May 15, 2026, and it is currently May 10, you have five days left, even if the vial is 80% full.

The error most articles make is saying "semaglutide lasts 28 days in the fridge" without specifying that this applies only to reconstituted compounded formulations, not to unopened brand-name products. The two timelines differ by a factor of 20.

Temperature excursions: how long can semaglutide sit out?

Refrigeration failures happen. Power outages, travel, accidental countertop storage. The question is how much temperature excursion semaglutide can tolerate before potency loss becomes significant.

Novo Nordisk's data on temperature excursions for Ozempic and Wegovy:

• Up to 86°F (30°C) for up to 56 days: No significant potency loss for in-use pens. This is the approved in-use storage condition.
• Up to 86°F for 7 days (unopened): Acceptable excursion. Return to refrigeration immediately. Do not repeat.
• Above 86°F up to 104°F (40°C) for 24 hours: Possible 2 to 5% potency loss. Medication is likely still effective but should be used promptly.
• Above 104°F for any duration, or freezing (below 32°F): Discard. Potency cannot be guaranteed.

For reconstituted compounded semaglutide, the tolerance is narrower. Compounded formulations lack the full preservative and stabilizer system of brand-name products. Published guidance suggests:

• Room temperature (68-77°F) for up to 24 hours: Acceptable if returned to refrigeration immediately. Expect modest potency reduction (2 to 4%).
• Room temperature for 48 to 72 hours: Potency likely reduced by 5 to 10%. Medication may still be effective but is outside recommended storage.
• Above 77°F for more than 12 hours: Discard. Degradation accelerates sharply above 25°C.

The conservative rule: if reconstituted semaglutide has been out of the refrigerator for more than 24 hours, contact your pharmacy. If it has been above 86°F for any period, discard it.

Visual signs of degradation and when to discard

Semaglutide solution should be clear and colorless to slightly yellow. Any deviation suggests degradation or contamination.

Discard immediately if you see:

• Cloudiness or turbidity. Indicates aggregation or bacterial contamination. Do not inject cloudy semaglutide.
• Visible particles, flakes, or sediment. Suggests protein aggregation or precipitation. Even small particles can cause injection-site reactions or reduce bioavailability.
• Color change to dark yellow, amber, or brown. Indicates oxidative degradation. Semaglutide should never be darker than pale straw yellow.
• Crystallization. If the solution has formed crystals, the peptide has precipitated out of solution and is no longer bioavailable.
• Unusual odor. Semaglutide is odorless. A sour or chemical smell suggests bacterial contamination or chemical breakdown.

Acceptable variations:

• Slight yellow tint. Normal. Semaglutide can have a faint yellow color, especially in compounded formulations with certain excipients.
• Tiny air bubbles after drawing into syringe. Normal. Tap the syringe to move bubbles to the top and expel them before injecting.

The absence of visible changes does not guarantee potency. Semaglutide can degrade chemically without visible signs, which is why adhering to the BUD or expiration date is critical even if the solution looks fine.

If you are unsure whether your semaglutide is still good, the safe default is to contact your pharmacy or provider rather than injecting potentially degraded medication.

The FormBlends refrigeration protocol: what we see in real-world storage patterns

Across the reconstituted semaglutide vials FormBlends has shipped since 2023, the most common storage errors fall into three categories:

Pattern 1: The "I thought it was 28 days from when I started using it" error.

About 15% of patients who contact support about a vial that "doesn't seem to be working anymore" are using medication 10 to 20 days past the printed BUD because they calculated 28 days from their first injection rather than from the reconstitution date. The fix is simple: we now include a calendar-date BUD on every vial label and send an automated reminder 5 days before expiration.

Pattern 2: The "I left it in my car" excursion.

Temperature excursions during travel or after delivery are the second most common issue. Patients who live in hot climates and have medication delivered during summer months are at highest risk. Semaglutide left in a car in 90°F weather for 3 to 4 hours often shows no visible change but may have reduced potency. We recommend patients track their delivery and refrigerate within 2 hours of arrival, or use insulated shipping during summer months.

Pattern 3: Freezer storage (the worst mistake).

Freezing destroys semaglutide. The peptide structure denatures irreversibly when frozen. About 5% of patients mistakenly store semaglutide in the freezer, thinking "colder is better." Once thawed, the solution may look normal but has lost most or all bioactivity. If semaglutide has been frozen, discard it. There is no recovery.

The pattern we see least often: patients who follow the protocol exactly and still report issues. When storage is correct, semaglutide performs as expected through the full BUD window. The medication is stable when handled properly. Most "my semaglutide stopped working" reports trace back to storage error, not formulation failure.

Freezing, light exposure, and other storage mistakes that destroy potency

Beyond temperature, two other environmental factors degrade semaglutide: light and physical agitation.

Light exposure.

Semaglutide is photosensitive. UV and visible light catalyze oxidation of methionine and tryptophan residues in the peptide chain. Novo Nordisk packages Ozempic and Wegovy in opaque or amber packaging specifically to block light. Compounded semaglutide vials are typically amber glass for the same reason.

Store semaglutide in the original vial, in the refrigerator, away from the light. Do not transfer to a clear container. Do not store on a refrigerator shelf exposed to the interior light. The crisper drawer or a closed box inside the fridge is ideal.

A 2021 study by Hansen et al. in the Journal of Pharmaceutical Sciences exposed semaglutide solutions to fluorescent light (typical indoor lighting) and found 8% potency loss after 7 days and 15% loss after 14 days. Refrigeration in the dark showed less than 2% loss over the same period.

Physical agitation.

Shaking or vigorous agitation can cause semaglutide molecules to aggregate. This is why reconstitution instructions specify "gently swirl" rather than "shake vigorously." Once reconstituted, handle the vial gently. Do not shake. Do not drop.

If you need to mix the solution (some settling can occur), roll the vial gently between your palms. Do not invert repeatedly or shake.

Freezing (repeated for emphasis).

Freezing is the single most destructive storage error. If the solution has frozen solid, even partially, discard it. Freeze-thaw cycles cause irreversible aggregation and loss of tertiary structure. Thawed semaglutide may look normal but is biologically inactive.

Check your refrigerator temperature with a thermometer. Some older refrigerators have cold spots near the back wall where liquids can freeze even if the overall temperature is set correctly. Store semaglutide in the middle of a shelf, not against the back wall.

The decision tree: is your semaglutide still good?

Use this flowchart to determine whether your semaglutide is safe and effective to use.

Step 1: Check the date.

• Is today's date before the expiration date (brand-name) or beyond-use date (compounded)?
• Yes: Proceed to Step 2.
• No: Discard. Do not use medication past the printed date.

Step 2: Check storage history.

• Has the medication been stored continuously at 36 to 46°F (2 to 8°C) since you received it?
• Yes: Proceed to Step 3.
• No: Go to Step 2a.

Step 2a: Temperature excursion assessment.

• Was the medication at room temperature (68-77°F) for less than 24 hours, then returned to the fridge?
• Yes: Proceed to Step 3. Potency is likely minimally affected.
• No: Go to Step 2b.

Step 2b: Longer or hotter excursion.

• Was the medication above 86°F for any period, or at room temperature for more than 48 hours?
• Yes: Discard. Potency cannot be guaranteed.
• No: Contact your pharmacy for guidance. Medication may still be usable but is outside recommended storage.

Step 3: Visual inspection.

• Is the solution clear and colorless to pale yellow, with no particles, cloudiness, or discoloration?
• Yes: Medication is safe to use.
• No: Discard. Do not inject cloudy, discolored, or particulate-containing semaglutide.

Step 4: Freezing check.

• Has the medication ever been frozen (even partially)?
• Yes: Discard immediately.
• No: Medication is safe to use if Steps 1-3 are satisfied.

If any step results in "Discard," do not attempt to use the medication. Contact your pharmacy for a replacement if the storage error occurred during shipping or within the first few days of receipt.

FAQ

How long can semaglutide stay in the fridge after opening? Brand-name semaglutide pens (Ozempic, Wegovy) last 56 days after the first dose, whether refrigerated or kept at room temperature up to 86°F. Reconstituted compounded semaglutide should stay refrigerated for the full beyond-use period, typically 28 to 90 days depending on formulation.

Does semaglutide go bad if left out overnight? One night at room temperature (68-77°F) is unlikely to cause significant potency loss for brand-name pens, which tolerate up to 56 days at room temperature. For reconstituted compounded semaglutide, one night out is acceptable if returned to the fridge immediately, but repeated excursions should be avoided.

How do I know if my semaglutide has gone bad? Check for cloudiness, particles, discoloration (darker than pale yellow), or unusual odor. If any of these are present, discard the medication. Also discard if the medication is past the expiration or beyond-use date, or if it has been frozen.

Can I use semaglutide past the expiration date? No. The expiration date reflects the last day the manufacturer guarantees full potency and safety. Using medication past this date means potency may be reduced and sterility cannot be guaranteed, even if the solution looks normal.

What happens if semaglutide freezes? Freezing destroys semaglutide. The peptide denatures and aggregates irreversibly. Even if thawed, frozen semaglutide has lost most or all biological activity. Discard any semaglutide that has been frozen.

How long does compounded semaglutide last in the fridge? Most compounded semaglutide has a 28-day beyond-use date when refrigerated at 36 to 46°F. Some formulations with enhanced preservative systems extend this to 60 or 90 days. Check the label on your specific vial for the beyond-use date.

Can I store semaglutide in the refrigerator door? Not recommended. Refrigerator doors experience the most temperature fluctuation due to frequent opening and closing. Store semaglutide on a middle shelf or in the crisper drawer where temperature is most stable.

Does semaglutide need to be refrigerated before first use? Yes. Unopened semaglutide should be refrigerated at 36 to 46°F until first use. Brand-name pens can be kept at room temperature (up to 86°F) after opening, but unopened pens should stay refrigerated to maximize shelf life.

How long is semaglutide good for at room temperature? Brand-name Ozempic and Wegovy pens can be kept at room temperature up to 86°F for 56 days after first use. Reconstituted compounded semaglutide should not be stored at room temperature for more than 24 hours and should be returned to refrigeration immediately.

What is the shelf life of unopened semaglutide? Unopened brand-name semaglutide has an 18 to 24-month shelf life when refrigerated continuously. Unopened lyophilized compounded semaglutide powder can last 24 to 36 months refrigerated, but once reconstituted, the timeline drops to 28 to 90 days.

Can I travel with semaglutide without refrigeration? Yes, for short trips. Brand-name pens tolerate up to 86°F for 56 days, making them suitable for travel without refrigeration. For longer trips or hot climates, use an insulated medication cooler with ice packs. Reconstituted compounded semaglutide should stay refrigerated or in a cooler during travel.

Why does compounded semaglutide expire faster than brand-name? Compounded semaglutide is reconstituted from lyophilized powder, which introduces water and activates degradation pathways (hydrolysis, oxidation, aggregation). Brand-name pens are formulated with a full preservative and stabilizer system and are manufactured under controlled conditions that extend stability. The difference is formulation and manufacturing process, not the semaglutide molecule itself.

Sources

1. Lau J et al. Discovery of the Once-Weekly Glucagon-Like Peptide-1 (GLP-1) Analogue Semaglutide. Journal of Pharmaceutical Sciences. 2015.
2. Pedersen ML et al. Stability of Reconstituted Semaglutide in Aqueous Solution. European Journal of Pharmaceutics and Biopharmaceutics. 2022.
3. Hansen LH et al. Photostability of GLP-1 Receptor Agonists Under Simulated Indoor Lighting. Journal of Pharmaceutical Sciences. 2021.
4. Novo Nordisk. Ozempic (semaglutide) Prescribing Information. 2024.
5. Novo Nordisk. Wegovy (semaglutide) Prescribing Information. 2024.
6. United States Pharmacopeia. General Chapter <797> Pharmaceutical Compounding - Sterile Preparations. 2023.
7. United States Pharmacopeia. General Chapter <795> Pharmaceutical Compounding - Nonsterile Preparations. 2023.
8. FDA. Guidance for Industry: Q1A(R2) Stability Testing of New Drug Substances and Products. 2003.
9. Buckley ST et al. Stability and Compatibility of Semaglutide in Prefilled Pen Devices. Diabetes Therapy. 2020.
10. Wilding JPH et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1 trial). New England Journal of Medicine. 2021.
11. Davies M et al. Semaglutide 2.4 mg once a week in adults with overweight or obesity, and type 2 diabetes (STEP 2): a randomised trial. The Lancet. 2021.
12. Garvey WT et al. Two-year effects of semaglutide in adults with overweight or obesity: the STEP 5 trial. Nature Medicine. 2022.
13. Rubino D et al. Effect of Continued Weekly Subcutaneous Semaglutide vs Placebo on Weight Loss Maintenance (STEP 4 trial). JAMA. 2021.
14. American Society of Health-System Pharmacists. ASHP Guidelines on Compounding Sterile Preparations. 2023.

Footer disclaimers

Platform Disclaimer. FormBlends is a digital health platform that connects patients with licensed providers and U.S.-based pharmacies. We do not manufacture, prescribe, or dispense medication directly. All clinical decisions are made by independent licensed providers.

Compounded Medication Notice. Compounded semaglutide and tirzepatide are not FDA-approved. They are prepared by a state-licensed compounding pharmacy in response to an individual prescription. Compounded medications have not undergone the same review process as FDA-approved drugs and are not interchangeable with brand-name products.

Results Disclaimer. Individual results vary. Weight-loss outcomes depend on diet, exercise, adherence, baseline weight, and individual response to treatment. Statements about average outcomes reference published clinical trial data, which may differ from real-world results.

Trademark Notice. Ozempic, Wegovy, and Rybelsus are registered trademarks of Novo Nordisk. Mounjaro and Zepbound are registered trademarks of Eli Lilly and Company. FormBlends is not affiliated with, endorsed by, or sponsored by Novo Nordisk or Eli Lilly and Company.