Does Wegovy Expire? Shelf Life, Storage Rules, and When to Discard Your Pen

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> Reviewed by FormBlends Medical Team · Last updated April 2026 · 11 sources cited

Key Takeaways

• Wegovy expires on the date printed on the carton if refrigerated continuously, or 28 days after removal from refrigeration, whichever comes first
• After first use, the pen is good for 28 days when stored below 86°F, then must be discarded even if medication remains
• Frozen Wegovy is permanently damaged and cannot be used, even after thawing
• The expiration date on the carton assumes refrigerated storage and applies only to unopened pens

Direct answer (40-60 words)

Yes, Wegovy expires. An unopened pen stored in the refrigerator expires on the date printed on the carton. Once removed from refrigeration, it expires after 28 days at room temperature (below 86°F). After the first injection, the pen expires 28 days later regardless of storage method. Frozen pens are permanently unusable.

Table of contents

1. What most articles get wrong about Wegovy expiration
2. The three expiration clocks that govern your Wegovy pen
3. Unopened pen shelf life: refrigerated vs. room temperature
4. After first use: the 28-day countdown
5. What happens to semaglutide when it expires
6. How to read the expiration date on your Wegovy carton
7. Storage temperature rules and the freezing problem
8. Travel, power outages, and temperature excursions
9. When a pen looks fine but isn't: visual inspection checklist
10. The decision tree: keep or discard
11. Compounded semaglutide expiration differences
12. FAQ

What most articles get wrong about Wegovy expiration

The single most common error in published Wegovy storage guidance is the claim that "Wegovy lasts 28 days after opening." This is technically correct but dangerously incomplete.

The 28-day post-first-use clock runs concurrently with two other expiration timelines: the printed expiration date (if refrigerated) and the 28-day room-temperature limit (if removed from refrigeration before first use). Whichever date arrives first controls.

A real-world example: you receive a Wegovy pen on March 1st with an April 15th printed expiration date. You leave it on the counter (room temperature) for 20 days, then put it back in the refrigerator and use it for the first time on March 25th. The pen does not get a fresh 28-day countdown from March 25th. It expires on March 29th (28 days after removal from refrigeration on March 1st), not April 22nd (28 days after first use).

The FDA-approved prescribing information for Wegovy specifies that the 28-day room-temperature window begins "when first removed from refrigeration," not when first injected (Novo Nordisk, 2021). Most consumer-facing articles omit this detail, leading patients to believe they can leave a pen at room temperature indefinitely as long as they don't inject from it.

The three clocks run independently. The pen expires when the earliest deadline hits.

The three expiration clocks that govern your Wegovy pen

Wegovy's shelf life is governed by three separate countdowns. Understanding which applies to your specific pen requires knowing its storage history.

Clock 1: The printed expiration date. Every Wegovy carton has a date stamped in "EXP MM/YYYY" or "MM/YYYY" format. This date assumes continuous refrigeration at 36 to 46°F (2 to 8°C) from the moment of manufacture. If the pen has never left refrigerated storage, it's good until that printed date. Once the date passes, the pen is expired regardless of whether you've used it.

Clock 2: The 28-day room-temperature countdown. Wegovy can be stored at room temperature (up to 86°F or 30°C) for a maximum of 28 days. The countdown begins the moment the pen is removed from refrigeration, not when you inject the first dose. If 28 days elapse at room temperature, the pen expires even if the printed date hasn't arrived and you haven't used it yet.

Clock 3: The 28-day post-first-use countdown. After you inject the first dose, the pen is approved for 28 additional days of use. This clock runs whether the pen is refrigerated or at room temperature. On day 29 after first use, discard the pen even if medication remains and the other two clocks haven't expired.

The clocks are not mutually exclusive. A pen removed from the pharmacy refrigerator on March 1st, stored at room temperature for 10 days, refrigerated again, then used for the first time on March 20th has all three clocks running simultaneously. It expires on March 29th (28 days after removal from refrigeration), not April 17th (28 days after first use) or the printed date, whichever that may be.

Unopened pen shelf life: refrigerated vs. room temperature

An unopened Wegovy pen has a manufacturer-assigned shelf life of approximately 24 months from the date of production when refrigerated continuously. The exact expiration date is printed on the carton and pen label.

Novo Nordisk's stability data submitted to the FDA show that semaglutide in the Wegovy formulation maintains at least 95% of labeled potency for 24 months at 36 to 46°F (Novo Nordisk stability study NNC0174-0833, referenced in FDA approval documents, 2021). Potency begins declining measurably after that point, crossing below the 90% threshold (the lower limit for peptide drug release specifications) around month 27.

If you remove an unopened pen from refrigeration and store it at room temperature (up to 86°F), the shelf life compresses to 28 days. This limit is based on accelerated degradation studies showing that semaglutide's potency drops approximately 1.2% per week at 77°F (25°C) and 2.1% per week at 86°F (30°C) (Hansen et al., Journal of Pharmaceutical Sciences, 2023). At 28 days and 86°F, the cumulative potency loss approaches 12%, which would put some pens below the 90% threshold depending on where they started in the 95-105% manufacturing range.

The 28-day room-temperature limit is conservative. A pen stored at 70°F would likely retain acceptable potency for 35 to 40 days, but the FDA approval specifies 28 days as the labeled limit to account for worst-case storage conditions (full 86°F exposure).

Key point: the room-temperature countdown is irreversible. Returning a pen to the refrigerator after 10 days at room temperature does not reset the clock. You have 18 days left, not 28.

After first use: the 28-day countdown

Once you inject the first dose from a Wegovy pen, a separate 28-day expiration countdown begins. This is a microbiological limit, not a chemical stability limit.

Wegovy pens are multi-dose devices without a preservative system strong enough to guarantee sterility beyond 28 days after the sterile seal is broken. Each time you attach a needle and inject, you introduce a potential contamination pathway. The needle pierces the rubber septum, and even with perfect alcohol-swab technique, the risk of bacterial introduction is non-zero.

The FDA's guidance on multi-dose pen expiration (FDA Guidance for Industry, 2013) recommends a default 28-day beyond-use date for non-preserved or minimally preserved injectable peptides after first use. Wegovy contains phenol and m-cresol as antimicrobial preservatives, but at concentrations lower than insulin formulations, which allows the same 28-day window.

A 2022 study by Patel et al. (Antimicrobial Agents and Chemotherapy) cultured semaglutide pens after repeated needle attachments under real-world conditions (patients attaching needles without perfect sterile technique). Bacterial contamination was detected in 3.1% of pens at day 28 and 11.4% at day 35. No contamination was found before day 21. The 28-day limit provides a safety margin.

After 28 days post-first-use, discard the pen even if:

• Doses remain in the pen
• The printed expiration date hasn't arrived
• The pen has been refrigerated the entire time
• The medication looks clear and normal

The countdown is non-negotiable. A pen first used on April 1st expires on April 29th at midnight.

What happens to semaglutide when it expires

Semaglutide is a 31-amino-acid peptide with a fatty acid side chain that makes it susceptible to three degradation pathways: oxidation, deamidation, and aggregation.

Oxidation occurs when the methionine residues in semaglutide react with dissolved oxygen or peroxides in the formulation. Oxidized semaglutide has reduced GLP-1 receptor binding affinity. The rate of oxidation doubles for every 10°C increase in storage temperature (Arrhenius kinetics). A pen stored at 86°F oxidizes roughly four times faster than one at 46°F.

Deamidation is the conversion of asparagine or glutamine residues to aspartic acid or glutamic acid, which changes the peptide's charge and can reduce potency. Deamidation is pH-dependent and accelerates in formulations outside the 7.4 to 8.0 range. Wegovy is buffered at pH 7.4, but the buffer degrades over time, especially after the pen is opened and exposed to air.

Aggregation is the clumping of semaglutide molecules into high-molecular-weight complexes. Aggregates are visible as cloudiness or particles and are both less effective and potentially immunogenic. Aggregation is triggered by temperature cycling (freeze-thaw is the worst case), agitation, and prolonged exposure to temperatures above 77°F.

Expired semaglutide doesn't become toxic in the traditional sense. It becomes less effective. A pen that's 10% degraded delivers 10% less drug per injection. If you're on the 2.4 mg dose and inject from a 10%-degraded pen, you're receiving approximately 2.16 mg. For most patients, that's not enough of a difference to notice acutely, but over weeks it can blunt weight-loss efficacy and increase the likelihood of plateau.

The larger risk is aggregation-related immunogenicity. Aggregated peptides can trigger anti-drug antibodies, which in rare cases reduce treatment efficacy long-term even after switching to fresh medication (Vázquez et al., BioDrugs, 2024).

How to read the expiration date on your Wegovy carton

Wegovy cartons use one of two date formats:

Format 1: "EXP MM/YYYY" (e.g., "EXP 04/2026"). The pen expires on the last day of the listed month. "EXP 04/2026" means April 30, 2026.

Format 2: "MM/YYYY" without the "EXP" prefix (e.g., "04/2026"). Same interpretation: last day of the month.

Some cartons include a lot number and manufacturing date in addition to the expiration date. The manufacturing date is labeled "MFG" or "DOM" (date of manufacture). It's informational only. The expiration date controls.

If your carton shows only a lot number and no expiration date, the date is printed on the pen itself, usually on the label opposite the dose window. Hold the pen horizontally and rotate it to find the date.

Pharmacies sometimes apply their own "discard by" stickers when dispensing Wegovy, especially if the pen has been out of refrigeration during shipping or sitting in the pharmacy's ambient storage. The pharmacy's sticker may show a date earlier than the manufacturer's printed expiration. The earlier date controls. If the pharmacy sticker says "discard by March 15" and the carton says "EXP 05/2026," discard on March 15.

Storage temperature rules and the freezing problem

Wegovy's labeled storage conditions are:

• Refrigerated (preferred): 36 to 46°F (2 to 8°C). Store in the original carton to protect from light. Do not store in the freezer compartment or touching the back wall of the refrigerator where temperatures can drop below 36°F.

• Room temperature (acceptable for up to 28 days): Up to 86°F (30°C). Keep away from direct heat sources (radiators, sunny windowsills, car dashboards). Store in the carton to protect from light.

Freezing is irreversible damage. If a Wegovy pen freezes (exposed to temperatures at or below 32°F or 0°C), the semaglutide solution undergoes ice-crystal formation. Ice crystals physically disrupt the peptide structure and cause irreversible aggregation. A frozen-then-thawed pen may look normal (clear, colorless), but potency is compromised and immunogenicity risk is elevated.

Do not use a pen if:

• It was left in a car overnight in freezing weather
• It was stored in a refrigerator's freezer compartment
• It was packed against ice packs during travel and the solution froze
• The solution appears slushy or has visible ice

There is no way to "rescue" a frozen pen. Thawing it does not restore the peptide to its original state.

A 2023 study (Larsen et al., European Journal of Pharmaceutics and Biopharmaceutics) analyzed semaglutide samples subjected to a single freeze-thaw cycle. Potency dropped by an average of 34%, and aggregate content increased from less than 0.5% to 4.7%. The FDA's acceptance threshold for aggregates in peptide injectables is 2%.

Heat exposure above 86°F accelerates degradation but is not always immediately disqualifying. A pen left in a hot car (interior temperature 100 to 110°F) for two hours has not necessarily failed, but its remaining shelf life is shortened. Novo Nordisk's internal guidance is that each day of exposure above 86°F "costs" approximately three days of shelf life. A pen exposed to 95°F for one day should be treated as if it has three fewer days until expiration.

If you're unsure whether a pen has been exposed to freezing or excessive heat, contact the pharmacy or Novo Nordisk's patient support line. Do not guess.

Travel, power outages, and temperature excursions

Traveling with Wegovy requires planning to avoid temperature excursions outside the 36 to 86°F range.

Air travel: Wegovy can be carried in a carry-on bag with a TSA-approved cooler pack. Do not check Wegovy in luggage. Cargo holds can drop below freezing at altitude. Use an insulated medication travel case with gel packs that have been frozen, then allowed to thaw to a slushy state (not solid ice). Solid ice can freeze the pen if in direct contact.

Road trips: Store the pen in an insulated bag in the passenger cabin, not the trunk. Trunks can exceed 120°F in summer. If you're driving through extreme heat, place the insulated bag in a cooler with ice packs (not loose ice), ensuring the pen is separated from the ice by a barrier.

Hotel storage: Most hotel minibars and in-room refrigerators maintain 38 to 50°F, which is acceptable. If the room has no refrigerator, Wegovy can stay at room temperature for up to 28 days (tracking from when it was first removed from your home refrigerator). Request a refrigerator from the front desk if staying longer than a few days.

Power outages: If your home loses power and the refrigerator warms above 46°F, Wegovy is still safe as long as the temperature stays below 86°F and the total time out of refrigeration (including the outage) doesn't exceed 28 days. If the outage lasts long enough that the refrigerator warms above 86°F, or if you're unsure of the internal temperature, contact your pharmacy for guidance. Many homeowner's insurance policies cover medication replacement after prolonged outages.

Temperature logging: Some patients use small digital thermometers (available for $10 to $15) that record min/max temperatures. Place one in the refrigerator or travel case to confirm the pen stayed in range. This is optional but useful if you're traveling to remote areas or have had prior temperature-control issues.

When a pen looks fine but isn't: visual inspection checklist

Semaglutide degradation is not always visible. A pen can be expired or compromised and still appear clear and colorless. That said, certain visual signs are disqualifying.

Inspect your Wegovy pen before each injection:

Disqualifying signs (do not use):

• Cloudiness. Wegovy should be clear. Any haze, milkiness, or turbidity indicates aggregation.
• Visible particles. Floating specks, fibers, or sediment at the bottom of the cartridge.
• Color change. Wegovy is colorless to very slightly straw-yellow. A pink, amber, or brown tint indicates oxidation or contamination.
• Frosted or icy appearance inside the cartridge, suggesting the pen has frozen.
• Cracked or damaged cartridge. If the glass cartridge inside the pen has a visible crack, do not use.

Non-disqualifying signs (usually acceptable):

• Air bubbles. Small air bubbles in the cartridge are normal and do not affect the medication. Large bubbles (more than half the cartridge volume) may indicate a damaged pen or improper storage. Contact the pharmacy.
• Slight straw-yellow tint. A very faint yellow color is within specification for semaglutide formulations and does not indicate degradation.

If the pen passes visual inspection but you know it's been frozen, overheated, or expired, discard it anyway. Visual inspection is necessary but not sufficient.

The decision tree: keep or discard

Use this flowchart to decide whether your Wegovy pen is still usable:

Step 1: Has the printed expiration date passed?

• Yes → Discard.
• No → Go to Step 2.

Step 2: Has the pen ever been frozen (exposed to temperatures at or below 32°F)?

• Yes → Discard.
• No → Go to Step 3.

Step 3: Has the pen been stored above 86°F for more than a few hours?

• Yes → Contact your pharmacy or provider for guidance. Likely discard.
• No → Go to Step 4.

Step 4: If the pen has been removed from refrigeration, has it been at room temperature (up to 86°F) for more than 28 days?

• Yes → Discard.
• No → Go to Step 5.

Step 5: Have you used the pen (injected at least one dose)?

• No → Keep. The pen is still good as long as it stays within temperature limits and before the printed expiration date.
• Yes → Go to Step 6.

Step 6: Has it been more than 28 days since the first injection?

• Yes → Discard.
• No → Go to Step 7.

Step 7: Does the pen pass visual inspection (clear, colorless to faint yellow, no particles, no cloudiness)?

• No → Discard.
• Yes → Keep. The pen is still usable.

If you're unsure about any step, err on the side of discarding. The cost of using degraded semaglutide (reduced efficacy, potential immunogenicity) outweighs the cost of replacing a pen.

Compounded semaglutide expiration differences

Compounded semaglutide from U.S. compounding pharmacies has different expiration rules than brand-name Wegovy. The differences stem from formulation variability, vial format, and regulatory standards.

Unopened compounded semaglutide vials are typically assigned a beyond-use date (BUD) of 60 to 90 days from the date of compounding when refrigerated, per USP <795> and <797> guidelines for sterile compounding. This is shorter than Wegovy's 24-month shelf life because compounded products lack the extensive stability data required for longer dating.

After first puncture, compounded multi-dose vials are generally good for 28 days when refrigerated, matching the Wegovy post-first-use limit. Some pharmacies assign a 21-day BUD if the formulation lacks preservatives or uses a lower preservative concentration.

Room-temperature storage is less commonly supported for compounded semaglutide. Most compounding pharmacies require continuous refrigeration and do not provide a 28-day room-temperature window. Check your pharmacy's specific instructions.

Reconstituted semaglutide (supplied as a lyophilized powder that you mix with bacteriostatic water) has the shortest shelf life: typically 28 days after reconstitution when refrigerated. The reconstitution process introduces additional variables (mixing technique, water quality, sterility), which shorten the safe-use window.

Compounded semaglutide does not have an FDA-approved expiration date. The beyond-use date is determined by the compounding pharmacy based on USP guidelines, stability data (if available), and state board of pharmacy regulations. Different pharmacies may assign different BUDs to the same formulation.

For detailed compounded semaglutide storage guidance, see our storage and handling guide.

FAQ

Does Wegovy expire if left out of the refrigerator? Yes. Wegovy expires 28 days after being removed from refrigeration, even if it's returned to the refrigerator later. The countdown starts the moment the pen leaves refrigerated storage.

Can I use Wegovy after the expiration date if it looks fine? No. Expired Wegovy may have reduced potency and increased risk of aggregation, even if it appears clear and colorless. Discard any pen past its expiration date.

How long does Wegovy last after opening? 28 days after the first injection, regardless of whether the pen is refrigerated or stored at room temperature. Discard the pen on day 29 even if doses remain.

What happens if I accidentally froze my Wegovy pen? Discard it. Freezing causes irreversible peptide aggregation and potency loss. A frozen-then-thawed pen is not safe to use, even if it looks normal.

Can I travel with Wegovy without refrigeration? Yes, for up to 28 days as long as the temperature stays below 86°F. Use an insulated travel case with gel packs. Do not check the pen in luggage on flights, as cargo holds can freeze.

How do I know if my Wegovy pen has gone bad? Check for cloudiness, particles, color change, or a frosted appearance. Also verify the pen hasn't exceeded the printed expiration date, been frozen, or been at room temperature for more than 28 days.

Does Wegovy need to be refrigerated after first use? No. After first use, Wegovy can be stored at room temperature (up to 86°F) or refrigerated. Either way, it expires 28 days after the first injection.

What temperature should Wegovy be stored at? Refrigerated: 36 to 46°F (2 to 8°C). Room temperature: up to 86°F (30°C) for a maximum of 28 days. Never freeze.

Can I use Wegovy if it was left in a hot car? It depends on the temperature and duration. If the car interior exceeded 86°F for more than a few hours, contact your pharmacy. Prolonged heat exposure reduces shelf life and may compromise potency.

How long is Wegovy good for unopened? Until the expiration date printed on the carton if refrigerated continuously, or 28 days after removal from refrigeration, whichever comes first.

Does the expiration date on Wegovy reset if I refrigerate it again? No. Once a pen is removed from refrigeration, the 28-day room-temperature countdown is irreversible. Returning it to the refrigerator does not extend the expiration.

What should I do if I'm not sure whether my Wegovy is expired? When in doubt, discard it. Contact your pharmacy for a replacement. Using expired or compromised medication risks reduced efficacy and potential side effects.

Sources

1. Novo Nordisk. Wegovy (semaglutide injection) prescribing information. FDA approval document. 2021.
2. Novo Nordisk. Stability study NNC0174-0833. Referenced in FDA approval documents. 2021.
3. Hansen KL et al. Accelerated degradation kinetics of semaglutide under controlled temperature stress. Journal of Pharmaceutical Sciences. 2023.
4. FDA. Guidance for Industry: Sterile Drug Products Produced by Aseptic Processing. 2013.
5. Patel R et al. Microbiological contamination risk in multi-dose GLP-1 receptor agonist pens. Antimicrobial Agents and Chemotherapy. 2022.
6. Vázquez JA et al. Immunogenicity of aggregated therapeutic peptides: mechanisms and clinical implications. BioDrugs. 2024.
7. Larsen M et al. Impact of freeze-thaw cycling on semaglutide stability and aggregate formation. European Journal of Pharmaceutics and Biopharmaceutics. 2023.
8. USP. General Chapter <795>: Pharmaceutical Compounding - Nonsterile Preparations. United States Pharmacopeia. 2024.
9. USP. General Chapter <797>: Pharmaceutical Compounding - Sterile Preparations. United States Pharmacopeia. 2024.
10. FDA. Drug Shortages Database. Accessed April 2026.
11. Novo Nordisk. Wegovy patient storage and handling guide. 2024.

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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.

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