Semaglutide is a temperature-sensitive medication that comes in pre-filled pens (Ozempic, Wegovy) or multi-dose vials (compounded versions). Like most injectable biologics, it has strict storage rules to keep it potent and safe. The question of whether it expires after exactly 28 days arises because many people confuse the beyond-use date of compounded vials with the branded pen guidelines.
Branded pens and compounded formulations follow different timelines. An opened branded pen is safe for up to 56 days when stored correctly, while most compounded semaglutide vials carry a beyond-use date of 28 days after first puncture. These numbers are not arbitrary—they come from stability testing that measures potency, sterility, and physical integrity over time.
Understanding the difference between expiration dates, beyond-use dates, and safe storage windows helps prevent wasted medication or reduced effectiveness. Using semaglutide past its safe period can lead to weaker blood sugar control or less appetite suppression. This article explains the official rules for both branded and compounded products, what happens if you exceed the time limit, and how to store it properly at home or while traveling.
Storage Rules for Branded Semaglutide Pens
Novo Nordisk sets the same storage requirements for Ozempic and Wegovy pens. Unopened pens must stay refrigerated at 2–8 °C (36–46 °F) until the expiration date printed on the label and carton. Never freeze them—freezing damages the protein structure and makes the pen unsafe to use even after thawing.
Once you perform the first injection (after removing the cap and priming the pen), the storage rules change. The pen can then be kept either refrigerated or at controlled room temperature up to 30 °C (86 °F). In both cases, you must discard the pen 56 days (8 weeks) after that first use, even if there is still medication left inside.
The 56-day window is based on stability studies showing the solution remains within potency and sterility specifications during that period. After 56 days, the risk of reduced effectiveness or bacterial growth increases, so the pen should be thrown away regardless of appearance or remaining doses.
Branded Pen Storage Summary
- Unopened: Refrigerate at 2–8 °C until carton expiration date
- After first use: Refrigerate or keep at ≤30 °C (86 °F)
- Maximum duration after first use: 56 days (discard after 8 weeks)
- Never freeze or expose to direct sunlight
Always check both the carton and the pen label for exact dates.
Storage Rules for Compounded Semaglutide Vials
Compounded semaglutide (custom-made by pharmacies) has stricter requirements than branded pens because it lacks the same preservatives and stabilizing excipients. Most compounding pharmacies require continuous refrigeration at 2–8 °C (36–46 °F) for both unopened and in-use vials. Room-temperature storage is rarely allowed unless the pharmacy specifically states it is safe for a short period.
The beyond-use date (BUD) is the key time limit for compounded products. The BUD is usually 28 days after the vial is first punctured or the syringe is filled. Some pharmacies assign shorter BUDs (14–28 days) if preservatives are minimal or absent. Freezing is not recommended—it can cause the solution to separate or degrade the active ingredient.
The 28-day BUD is based on USP <797> guidelines for sterile compounding and stability testing performed by the pharmacy. After the BUD, the risk of bacterial growth, potency loss, or physical changes increases, so the vial must be discarded even if solution remains.
Compounded Vial Storage Summary
- Unopened vial: Refrigerate at 2–8 °C
- After first puncture/use: Refrigerate continuously
- Beyond-use date: Usually 28 days (check pharmacy label)
- Do not freeze or leave at room temperature long-term
Pharmacy-specific instructions always take priority.
Comparison: Branded Pens vs Compounded Vials – Time & Temperature Limits
| Aspect | Branded Semaglutide Pens (Ozempic/Wegovy) | Compounded Semaglutide Vials |
|---|---|---|
| Unopened storage | Refrigerate until expiration date | Refrigerate until beyond-use date |
| After first use | Refrigerate or room temp ≤30 °C (86 °F) | Refrigerate continuously |
| Maximum safe time after first use | 56 days | 28 days (most common BUD) |
| Tolerance to brief room temp | Yes, up to 56 days at ≤30 °C | Usually no—check pharmacy label |
| What to do if frozen | Discard immediately | Discard immediately |
This table shows why branded pens offer more travel flexibility than most compounded versions.
What Happens If You Use Semaglutide After 28 Days or 56 Days
Using a branded pen after the 56-day in-use period or a compounded vial after the BUD increases the risk of reduced potency. The active peptide can degrade slowly, meaning each injection may deliver less semaglutide than intended. Blood sugar control may weaken, appetite suppression may lessen, and weight-loss progress can slow or stall.
Sterility is another concern. After the safe period, the risk of bacterial growth inside the pen or vial rises, especially if the product has been handled multiple times. Contaminated solution can cause injection-site infections or more serious systemic infections in rare cases.
Physical changes (cloudiness, particles, discoloration) are signs of degradation, but potency can drop before visible changes appear. For these reasons, both manufacturers and compounding pharmacies set conservative time limits—better to discard and replace than risk using an ineffective or unsafe product.
Signs a Pen or Vial Is No Longer Safe
- Past 56 days (branded) or BUD (compounded)
- Frozen at any point
- Exposed to prolonged heat (>30–40 °C for hours/days)
- Cloudy, discolored, or contains particles
- Unusual odor or leaks
Discard immediately if any of these apply.
Safe Travel & Emergency Storage Tips
For short trips (a few days), an in-use branded pen can stay at room temperature if kept below 30 °C. Use an insulated cooler bag with gel ice packs (not loose ice) for longer travel or for compounded vials that require refrigeration. Keep the cooler in carry-on luggage—never check it in the hold.
During flights, TSA allows injectable medications and supplies in carry-on. Declare them at screening and place them in a separate bin for X-ray. A prescription copy or doctor’s letter is not required by TSA but is recommended for international travel or questions.
If staying in hotels, use the mini-fridge if available (check temperature first—some run too cold and can freeze). For remote travel or camping, portable medical-grade coolers with battery power are ideal for compounded versions. Branded pens can be kept in a standard cooler with ice packs for shorter trips.
Travel Storage Checklist
- Insulated cooler bag with gel packs
- Medication in carry-on only
- Prescription copy or doctor’s letter
- Extra needles/syringes/alcohol swabs
- Portable sharps container
- Avoid direct sunlight or hot car interiors
Plan ahead to prevent temperature excursions.
What to Do If Your Semaglutide Gets Warm
If a pen or vial has been exposed to warmth, evaluate the duration and temperature. Brief exposure (a few hours at 30–40 °C) is usually safe for in-use branded pens. Longer or hotter exposure (above 40 °C for more than a few hours) increases degradation risk—discard the product.
Inspect the solution before every injection. Branded pens should be clear and colorless with no particles, cloudiness, or discoloration. Compounded vials should meet the same criteria. If anything looks abnormal, discard immediately.
If the medication has been exposed to known excessive heat but looks normal, err on the side of caution and discard it. Using degraded semaglutide can lead to poor blood sugar control or inadequate weight-loss effect. Contact your pharmacy or provider for a replacement.
What to Check After Heat Exposure
- Clear, colorless solution (no cloudiness/particles)
- No unusual odor
- No discoloration (yellowing/browning)
- Within expiration or beyond-use date
- No leaks or damage to pen/vial
Discard if any check fails.
Conclusion
Semaglutide remains stable and effective within the manufacturer’s specified temperature ranges—refrigerated unopened, refrigerated or ≤30 °C after first use for branded pens, and continuous refrigeration for most compounded versions. Brief warmth is usually tolerated, but prolonged high temperatures or freezing cause degradation and require discarding the product. Proper storage, coolers for travel, and careful inspection before each use keep the medication safe and potent.
FAQ
How long can Ozempic or Wegovy stay out of the fridge after first use?
Opened branded pens are stable at room temperature up to 30 °C (86 °F) for 56 days. After that, discard even if refrigerated. Protect from direct light and extreme heat.
How long does compounded semaglutide last after first use?
Most compounded vials have a beyond-use date of 28 days after first puncture or filling. Some pharmacies set 14–30 days. Always follow the exact date on your pharmacy label and keep refrigerated continuously.
What happens if semaglutide is left at room temperature too long?
Branded pens left out longer than 56 days after first use lose potency and should be discarded. Compounded versions left out for more than a few hours (check label) may degrade or become contaminated. Discard if in doubt.
Can semaglutide be frozen accidentally?
No—freezing damages the active ingredient. Discard any pen or vial that has been frozen, even if it thaws. Never store in the freezer compartment or near cooling vents.
How do I know if my semaglutide has been damaged by heat?
Check that the solution is clear and colorless with no particles, cloudiness, discoloration, or unusual odor. If it looks abnormal or has been exposed to prolonged high heat (>40 °C), discard it even if it appears normal.
Should I refrigerate semaglutide during travel?
Yes—use an insulated cooler bag with gel packs to keep it at 2–8 °C. For short trips, opened branded pens can stay at room temperature up to 30 °C. Keep in carry-on luggage.
What if my shipped semaglutide arrives warm?
Inspect the solution immediately. If it looks normal (clear, colorless, no particles), branded pens are usually safe after brief shipping warmth. If cloudy, discolored, or exposed to excessive heat, discard it and contact your pharmacy.
How should I store unopened semaglutide pens?
Keep unopened branded pens refrigerated at 2–8 °C until the expiration date on the label. Do not freeze. Compounded vials should also be refrigerated continuously until first use.
Can semaglutide be stored at room temperature the whole time?
Branded pens can be kept at room temperature after first use for up to 56 days if ≤30 °C. Compounded versions usually require continuous refrigeration. Follow the specific instructions provided with your product.
What should I do if I’m not sure whether my semaglutide is still good after warmth exposure?
Err on the side of caution and discard it if it has been outside recommended conditions for more than a short time or if it looks abnormal. Contact your pharmacy or prescriber for guidance and a replacement. Using compromised medication can reduce effectiveness or cause harm.
Dr. Usman is a medical content reviewer with 12+ years of experience in healthcare research and patient education. He specializes in evidence-based health information, medications, and chronic health topics. His work is based on trusted medical sources and current clinical guidelines to ensure accuracy, transparency, and reliability. Content reviewed by Dr. Usman is for educational purposes and does not replace professional medical advice.