Does Semaglutide Expire — and What Happens When It Does?

The decision in front of you: use it, hold it, or replace it?

Most people asking whether semaglutide expires are holding a pen and making a real-time call. Maybe it's been in the fridge door for longer than expected, maybe you found one in a travel bag, or maybe the date on the box is coming up fast. The honest answer is that the expiry date printed on a Wegovy pen is a hard boundary, not a guideline. After that date, the manufacturer can no longer guarantee the medicine works as tested. Potency may have declined; the pen should not be used.

Before that date, the question shifts to storage. Semaglutide is a protein-based molecule and it is sensitive to temperature. An unopened pen kept at 2–8°C, away from the freezer compartment, will remain within specification until its printed date. A pen that has been frozen, left in a hot car, or left out on a worktop for longer than the permitted room-temperature window may have degraded well before that date, even though the liquid still looks clear. Cloudiness, particles or discolouration are reasons to discard the pen immediately, but a clean appearance is not confirmation that all is well.

If you are unsure whether your pen has been stored correctly, the risk of using compromised semaglutide is worth understanding before you make the call. When in doubt, contact your prescriber or pharmacist, that is the right route, every time.

The two clocks running on every pen: expiry date and in-use limit

This is where a lot of confusion comes in. Semaglutide pens actually run on two separate timelines, and mixing them up leads to mistakes.

The first is the printed expiry date, the month and year stamped on the outer carton and the pen itself. This is fixed from manufacture and applies regardless of when you open the pen.

The second is the in-use period, which starts the moment you take the first dose from a pen. The Wegovy SmPC sets a specific maximum number of days a pen may be kept once it has been used. The detail on when semaglutide expires in practice depends on which of these two clocks runs out first, whichever comes sooner is the limit you must observe. The exact in-use figure is published in the Patient Information Leaflet that comes with your pen; always check it there rather than relying on a figure recalled from a forum or remembered from a different medicine.

The Wegovy SmPC is available on the electronic Medicines Compendium (eMC), which is the authoritative source for storage windows, in-use limits and full prescribing information.

Room temperature, travel and the fridge: practical storage in real life

In practice, Wegovy pens live in the fridge, ideally on a shelf rather than the door, where temperature fluctuates slightly with each opening. That works for most people most of the time. Travel complicates things. Pens can be kept at room temperature (up to 30°C) for a limited period once removed from the fridge, and the Patient Information Leaflet states that window precisely. The pen does not need to go back into the fridge once you have started using room-temperature storage, but the clock does not pause.

The thing to avoid is anything extreme: direct sunlight, the glove compartment of a car on a summer afternoon, a freezer compartment that the pen accidentally rolls into. Freezing damages the formulation even if the pen thaws and looks fine afterwards. How Wegovy behaves specifically during refrigerated storage covers this in more depth, including what to do if a fridge develops a fault.

If you are travelling for longer than the room-temperature window allows, a small insulated medical pouch (not an ice pack directly touching the pen, that risks freezing) is a practical solution. Some people also ask about lyophilised formats; storage for lyophilised semaglutide follows different rules and is covered separately.

For cost context on Wegovy treatment overall, the private prescription route and what to expect on pricing is worth reading before you start.

Reporting problems and what to do with a pen you cannot use

If you have a pen that has expired, been stored incorrectly, or looks unusual, do not inject it. Dispose of used pens and sharps safely, a sharps container is the correct way to discard them, not a household bin.

The NHS semaglutide medicines page sets out general guidance on the medicine, and any suspected quality problem with a pen (unusual appearance, unexpected reaction) can be reported directly to the MHRA via the Yellow Card scheme. That reporting route exists for patients as well as healthcare professionals, and it is how the regulator tracks real-world safety signals.

If you are mid-treatment and a pen becomes unusable, contact your prescriber before skipping a dose or trying to adjust timing yourself. The effect of a missed or delayed dose on your titration schedule is a clinical question, not one to work out alone. At nume, a real clinician reads every query, if you have an aftercare question, our team is available seven days a week.

Not yet on treatment? Start your free consultation and a GPhC-registered prescriber will review your case the same day.