How Long Can You Keep Semaglutide Before It Goes Off?

What the licensed guidance says about semaglutide shelf life

The SmPC and Patient Information Leaflet for Wegovy, accessible via the eMC, are the authoritative source on storage. The headline rules are clear: unopened pens belong in a fridge at 2–8°C, away from the freezer compartment and away from direct light. Once you take a pen out and use it for the first time, the clock starts on a room-temperature window, the exact duration is printed in the leaflet and can vary slightly between product versions, so read your own copy rather than relying on a number quoted online.

Six weeks is the maximum period a pen should be in use after the first injection. Wegovy delivers one dose a week, and each pen is designed for four weekly injections, so in normal use the pen is finished well within that window. The six-week rule becomes relevant if you miss a dose, delay treatment or find a half-used pen that has been sitting in your bag. In those cases, check the start date you noted when you first used it. If you cannot remember when you opened it, the safest course is to discard the pen and order a replacement.

Potency matters here. Semaglutide is a peptide, and peptides are sensitive to temperature extremes and prolonged exposure to air and light. A pen that has been stored incorrectly may look identical to one that has not (the liquid remains clear) but the active ingredient may have broken down. Injecting a degraded dose does not just mean less effect; it means you lose the progress of that week entirely, which compounds over a course of treatment, particularly for anyone who wants to understand how long you can use semaglutide and why consistency across the titration schedule is so closely linked to outcome.

Room temperature and travel: the practicalities

Most people encounter the room-temperature rule on holiday or during a period when the fridge is unavailable. The good news is that Wegovy's labelling does allow a brief period at temperatures up to 30°C, the exact duration is stated in the leaflet. Think of it the way you might think about keeping medication in a cool bag on a day trip: entirely manageable with a little planning, but not an excuse to leave a pen on the windowsill all week.

During travel, an insulated cool pouch (not a full ice pack pressed directly against the pen, freezing ruins the medicine as surely as overheating does) keeps conditions within range. If you are flying, keep the pen in hand luggage; the cargo hold can drop well below freezing. At your destination, put the pen in the room fridge the same evening you arrive. If your hotel room has no fridge, ask at reception, this is a reasonable medical request and most hotels will store medication safely.

Questions about longer trips or specific travel scenarios are exactly the kind of thing worth raising during your clinical review. A prescriber can flag any timing issues before they become a problem, rather than after a pen has been left out for too long. For more on the journey from first dose to results, the guide to how long Wegovy takes to work covers what to expect week by week.

Pen condition: when to discard without hesitation

Even within the permitted storage window, a pen should not be used if the solution looks cloudy, coloured or contains visible particles. Wegovy is a clear, colourless to slightly yellow liquid; any deviation from that is grounds for disposal. Similarly, if the pen has been dropped and you suspect the mechanism is damaged, do not attempt to use it. The dose counter may advance without medicine being delivered, meaning you lose a week of treatment without knowing.

Disposal matters too. Used pens and needles are sharps and cannot go in the household bin. A sharps container is the correct receptacle; local pharmacies and GP surgeries usually accept filled sharps containers for safe disposal.

If a pen was left out of the fridge and you are unsure whether it is still safe to use, the right call is to contact your prescriber or the pharmacy rather than guess. At nume, our support team is available seven days a week for exactly these questions, no need to wait until Monday morning when you notice the pen left on the kitchen counter over the weekend.

How storage connects to long-term treatment planning

Understanding storage is not just about a single pen. People who stay on semaglutide for an extended period (and the question of how long you can continue treatment is one our prescribers discuss at every review) need to build storage habits that work across months, not just weeks. That means a consistent spot in the fridge door (away from the freezer end), a note of the date each new pen is first used, and a plan for any travel periods in advance.

One practical detail that catches people out: ordering your next pen too late. If your pen arrives on a Friday and you planned to inject that evening, the pen has its full window ahead of it. But if a delivery is delayed and you are already mid-week without a replacement, the gap affects your titration schedule. Ordering by the 12pm cut-off on a weekday means a next-working-day delivery with DPD, which removes most of that uncertainty.

For anyone thinking about what happens to weight once treatment eventually ends, the guidance on maintaining weight loss after semaglutide is worth reading alongside the storage basics. The two go together: handling the medicine correctly during treatment sets the foundation for results you can build on. If you would like to discuss your own treatment plan, start your free consultation and a GPhC-registered prescriber will review your case the same day.