An unopened semaglutide pen lasts until the printed expiration date when stored in the refrigerator between 36 and 46 degrees Fahrenheit. Once the pen is in first use, both Wegovy and Ozempic remain stable for 56 days either in the fridge or at room temperature up to 86 degrees Fahrenheit. Never freeze semaglutide. Compounded semaglutide vials follow shorter beyond-use dates set by the compounding pharmacy.
Storage Rules at a Glance
| Stage | Refrigerator (36–46 F) | Room Temperature (under 86 F) |
|---|---|---|
| Unopened pen | Until printed expiration | Not recommended (use within 28 days if accidentally left out) |
| Opened Wegovy pen | 56 days from first use | 56 days from first use |
| Opened Ozempic pen | 56 days from first use | 56 days from first use |
| Rybelsus tablets | Not required (sealed) | Until printed expiration in original blister |
| Compounded vial | 28–90 days (per label) | Usually not allowed |
Why the Refrigerator Matters
Semaglutide is a peptide. Peptides degrade faster at higher temperatures because protein chains begin unfolding and aggregating, which reduces potency and can increase injection site reactions. Cold storage slows that degradation. The 36 to 46 degree window is calibrated for stability without freezing — freezing creates ice crystals that physically destroy the peptide structure.
Before First Use: The Easy Case
Keep the pen in its carton in the main body of the refrigerator. Avoid the door (temperature swings) and the back wall (risk of freezing). Each pen has a printed expiration date — typically 18 to 24 months from manufacture. Stored properly, it remains fully potent until that date.
- Original carton in the middle of a fridge shelf
- Out of direct light
- Not next to the freezer compartment
- Refrigerator thermometer to confirm temperature
After First Use: The 56-Day Clock
The moment you uncap a pen and inject for the first time, a 56-day countdown begins. After that, discard it whether you finish the medication or not. You can keep it refrigerated for stable temperature, or at room temperature for convenience.
- Mark the date of first use on the pen with a permanent marker
- Replace the cap between uses
- Do not store with a needle attached
- Keep pens out of direct sunlight and away from heat sources
Most monthly supplies of weekly Wegovy or Ozempic have four doses in a pen. The 56-day window is enough time for typical weekly dosing.
What If a Pen Was Left Out?
| Scenario | Likely Outcome |
|---|---|
| Unopened pen at room temp under 86 F for under 28 days | Usually safe; refrigerate again, monitor potency |
| Pen exposed to direct sunlight | Discard — UV degrades the peptide |
| Pen left in a hot car (over 86 F) | Discard — heat exceeds stability range |
| Pen frozen and thawed | Discard always — even if clear, peptide is destroyed |
| In-use pen at room temp under 86 F | Continue using up to 56 days from first use |
Compounded Semaglutide: Different Rules
Compounded semaglutide vials have their own beyond-use date assigned by the compounding pharmacy under USP Chapter 797 rules. Common labels include:
- 28 to 45 days for multi-dose vials with bacteriostatic water
- 9 to 14 days at room temperature for some preparations
- 90 days under refrigeration for higher-stability formulations
Always follow the pharmacy’s printed beyond-use date — it accounts for the specific carrier, preservative system, and sterility risk for that batch. See our overview of treatment options for more on compounded versus brand semaglutide.
Travel Tips
- Use an insulated medication travel case with a thin ice pack (gel pack between cardboard, not touching the pen)
- For flights, carry pens in cabin luggage — cargo holds freeze
- Keep manufacturer information and the prescription label visible for security screening
- Avoid leaving pens in a parked car at any time
- For trips longer than 56 days from first use, pack a fresh sealed pen and start fresh
Signs a Pen May Be Compromised
- Solution is cloudy, discolored, or contains visible particles
- Pen has been frozen and thawed
- Mechanism feels different (button hard to press, plunger inconsistent)
- Strong unusual odor when cap is removed
- Past 56 days from first use
- Past printed expiration date
If any of these apply, discard in a sharps container and ask your pharmacy for a replacement.
Related Reading
For more on semaglutide use and storage of injection supplies, see our guides on treatment and prediabetes basics.
The Bottom Line
An unopened semaglutide pen lasts until the printed expiration date in the refrigerator. Once you start using it, both Wegovy and Ozempic stay stable for 56 days at either fridge or room temperature up to 86 degrees Fahrenheit. Never freeze a pen. Compounded vials follow shorter pharmacy-set beyond-use dates. If a pen has been frozen, sun-exposed, or stored above 86 degrees Fahrenheit, discard it and contact your pharmacy. Mark the first-use date with a permanent marker so the 56-day window is easy to track.
