How long does Wegovy last unopened — and what affects its shelf life?

You've just had your Wegovy delivered — here's what to do in the first sixty seconds

The pen arrives at your door in a cool-pack. Before you even open the outer bag, the clock on usable room-temperature time has started. For an unopened pen, the single most important action is to transfer it to the fridge immediately, at a temperature between 2°C and 8°C. The back of a fridge shelf, away from the ice compartment, is ideal, anywhere the temperature holds steady rather than swinging when the door opens.

Once it's in the fridge, an unopened pen is stable until the expiry date printed on the carton. That date is set by Novo Nordisk's own stability data and represents the point beyond which potency cannot be guaranteed, even under perfect conditions. The expiry is month and year only, which means the pen is usable through the last day of that month. A practical checking habit: when you put a new pen in the fridge, take five seconds to read the expiry on the carton and compare it to the previous pen's date, a newer batch sometimes runs later, and spotting an unexpectedly short date early gives you time to query it with the dispensing pharmacy.

Semaglutide is the active ingredient in Wegovy, and its stability under refrigeration is well established from the manufacturer's filing with the MHRA. The pen design also matters, the pre-filled injector is sealed and light-resistant, which supports shelf life in the fridge. None of that protection applies once the pen has been opened, which is a separate question covered in detail on our page about how long a Wegovy pen lasts once opened.

What actually shortens an unopened pen's life before the expiry date

The expiry date assumes unbroken cold-chain storage. In practice, several things can shorten the effective life of an unopened pen before that date arrives.

Freezing is the most common problem. If a pen sits against the back wall of a fridge that runs very cold, or is stored in the freezer compartment by mistake, the suspension can be damaged in ways that are not visible to the naked eye. A frozen-and-thawed pen should not be used. Similarly, leaving a pen in a car on a warm day, or in a room with direct afternoon sun, can push temperatures well beyond the manufacturer's permitted room-temperature window. The Patient Information Leaflet gives a specific room-temperature limit and duration, always check those figures on the leaflet for your batch, because general web summaries are not a substitute for the labelled instruction.

Repeated temperature cycling (in and out of the fridge, warm for an hour, cold again) is more damaging than a single brief excursion of the same total duration. If you are unsure whether a pen has been stored correctly throughout its journey from pharmacy to your fridge, the safest course is to contact the dispensing pharmacy before using it. For more on how storage conditions interact with the pen's overall effective life, the page covering how long Wegovy lasts sets out the full picture.

Light exposure is a lesser but real factor. The outer carton and pen casing are designed to limit light reach, but prolonged exposure to direct sunlight can still degrade semaglutide. Keep the pen in its carton until you are ready to use it.

The expiry date versus the clinical timeline, what matters more for your treatment

People sometimes ask whether it is safe to stock up on Wegovy pens to avoid supply gaps. There is a practical storage consideration here: with an expiry roughly 30 months from manufacture, a pen dispensed today will typically have 12–24 months of usable refrigerated life remaining depending on when in the batch's life it was dispensed. That is a reasonable buffer, but it is not unlimited.

There is also a clinical dimension to this question. Wegovy is a prescription-only medicine, each supply is dispensed against a valid prescription following a clinical review. The prescriber assesses your dose at each stage; holding a large stock of one dose while your prescriber has moved you to another creates practical and safety complications. It is worth discussing your supply approach with your prescriber rather than managing it purely around fridge logistics.

If you are thinking about what happens between pens during treatment, the more clinically relevant question is often how long a Wegovy shot lasts and whether a missed or delayed dose affects results. Our page on how long Wegovy takes to work covers the treatment timeline in detail. For a broader look at how semaglutide behaves in the body across injection and oral formats, how long semaglutide lasts is a useful companion read.

Cost sometimes influences how people approach stocking. Wegovy is a private prescription in most cases, and the per-pen cost is a real consideration. Understanding what a legitimate supply actually includes (clinical review, dispensing, delivery, aftercare) is part of making an informed decision. Our weight-loss treatment overview explains the full picture of what private treatment involves.

When to stop and ask rather than proceed

There are clear situations where using an unopened pen is not the right call, even if it looks fine. If the liquid visible through the inspection window appears cloudy, discoloured or contains visible particles, do not inject it, semaglutide solution should be clear and colourless to slightly yellow. If the pen has been dropped and the mechanism may be damaged, do not assume it is unaffected. If you cannot confirm the pen was kept refrigerated from dispensing to delivery, treat the uncertainty as a reason to check rather than a reason to proceed.

Pharmacists are the right first call for storage queries about a specific pen. If you are a nume patient with a concern about a pen you have received, our aftercare team is available seven days a week, see how to reach us. For general questions about whether Wegovy is clinically appropriate for you, our prescribers are also the right people to talk to; the FAQs cover the most common questions, and if yours is not there, the consultation is the place to raise it. The clinical team at nume reviews every consultation personally before anything is dispensed.

Wegovy is a significant medicine and the storage rules exist for a reason. Getting them right from the first pen is straightforward once you know what to look for. If you are not yet on treatment and want to understand more about the medicine itself before starting, the Wegovy overview covers licensing, eligibility and what to expect from the treatment programme.