How long a vial of semaglutide lasts depends on whether you’re using a brand-name pen or a compounded multi-dose vial, and what dose you’re on. Brand-name Ozempic pens last up to 56 days (8 weeks) after first use, while Wegovy pens are single-dose and discarded immediately. Compounded semaglutide vials typically carry a 28-day beyond-use date once opened, though some pharmacies assign longer windows depending on their sterility testing.
Brand-Name Pens: Ozempic and Wegovy
Ozempic pens are multi-dose, meaning you’ll use the same pen for several weekly injections. Once you give your first injection, the pen stays good for 56 days whether you store it in the refrigerator (36°F to 46°F) or at room temperature (59°F to 86°F). After 56 days, you throw the pen away even if medication remains inside. Novo Nordisk, the manufacturer, instructs users to discard the pen after 8 weeks regardless of how much is left.
Wegovy pens work differently. Each pen contains a single dose, so you use it once and discard it. Before that first use, an unopened Wegovy pen can be stored outside the refrigerator (between 46°F and 86°F) for up to 28 days. After 28 days at warmer temperatures, or if it’s ever been exposed to temperatures above 86°F, the pen should be thrown away. The same goes for any pen that has been frozen or exposed to direct light.
How Dose Affects How Long a Pen Lasts
With Ozempic, the number of doses you get from one pen depends on your prescribed amount. The standard titration schedule starts at 0.25 mg once a week for the first four weeks, then increases to 0.5 mg. From there, your provider may raise it to 1 mg or up to the maximum of 2 mg per week. Each Ozempic pen is designed to deliver a set number of doses at a specific strength, and the pen itself contains enough medication for about four weekly injections. At lower doses like 0.25 mg, the pen technically contains more medication than you’ll use in four weeks, but the 56-day discard rule still applies.
For compounded semaglutide vials, the math works differently because you’re drawing custom doses from a larger vial. A 5 mg vial, for example, would provide 20 weekly doses at 0.25 mg but only 5 doses at 1 mg. The catch is that the vial’s expiration clock starts ticking the moment a needle punctures the stopper, so your dose level and the beyond-use date both determine how long it practically lasts.
Compounded Semaglutide Vials
Compounded semaglutide comes in multi-dose vials rather than pre-filled pens. These vials are mixed by compounding pharmacies and often contain bacteriostatic water, which includes a preservative that helps prevent bacterial growth after repeated needle punctures. Despite that preservative, standard pharmacy guidelines (based on USP chapter 797) set a default beyond-use date of 28 days for opened multi-dose vials unless the compounder has stability data supporting a longer window.
Some compounding pharmacies assign beyond-use dates of 60 or even 90 days based on their own testing, but those timelines vary. The key rule, according to the Joint Commission, is that the beyond-use date can never exceed the manufacturer’s original expiration date on the unopened vial. If your compounding pharmacy labels the vial with a specific discard date, that date is the one to follow.
Before you open a compounded vial, check whether it came with storage instructions. Most need refrigeration, and an unopened vial stored properly in the fridge can remain stable for months. Once opened, the clock starts, and the labeled beyond-use date takes over.
What Happens After a Vial Expires
Semaglutide is a protein-based medication, which makes it more fragile than a typical pill. Over time, the protein molecules can clump together or form tiny fibers, a process called aggregation. When that happens, you’re getting less active medication per injection than you think. There’s no visible change you’d notice in the liquid, so expired semaglutide can look perfectly fine while delivering a reduced dose.
Unopened and refrigerated, semaglutide is stable for about 36 months. But once a vial or pen is in use, exposure to air, temperature shifts, and repeated needle punctures all accelerate breakdown. That 6 to 8 week window after first use isn’t arbitrary. It reflects how quickly the active peptide degrades under real-world conditions. Using semaglutide past its labeled date doesn’t necessarily cause harm, but it may mean you’re not getting the therapeutic dose you need, which can stall weight loss or blood sugar control without an obvious explanation.
Storage Tips That Protect Potency
Temperature is the single biggest factor in how well semaglutide holds up. Refrigeration between 36°F and 46°F is ideal for both opened and unopened vials. Room temperature storage is acceptable within the labeled windows (56 days for Ozempic, 28 days for Wegovy or most compounded vials), but warmer conditions shorten the medication’s useful life. Never freeze semaglutide. Freezing damages the protein structure permanently, and a vial that has been frozen should be discarded even if it thaws and looks normal.
Keep vials and pens away from direct sunlight. Light exposure accelerates peptide degradation. If your compounded vial arrived in a box, store it in that box. For Ozempic and Wegovy pens, the FDA label specifically says to keep them in the original carton until you’re ready to inject.
If you’re traveling, a small insulated pouch with a cool pack works well for short trips. Avoid leaving semaglutide in a hot car, near a window, or in checked luggage where temperature swings are unpredictable. Any exposure above 86°F is grounds for discarding the medication.
Quick Reference by Product
- Ozempic pen (opened): 56 days (8 weeks), refrigerated or room temperature up to 86°F
- Wegovy pen (unopened, unrefrigerated): 28 days between 46°F and 86°F
- Wegovy pen (opened): single use, discard after one injection
- Compounded vial (opened): typically 28 days, unless the pharmacy’s label specifies otherwise
- Any semaglutide product (unopened, refrigerated): up to 36 months or the printed expiration date
When in doubt, go by the date on the label. If your vial has no date or you’ve lost track of when you opened it, the safest approach is to replace it. The cost of a wasted vial is far less than weeks of injecting medication that’s lost its potency.