Does Wegovy go bad — and how would you know?

What official guidance says about Wegovy degrading

The starting point for any storage question is the product's Summary of Product Characteristics (SmPC), published on the Electronic Medicines Compendium (eMC). For Wegovy, the licensed manufacturer Novo Nordisk specifies that the pre-filled pen is a biological medicine (a GLP-1 receptor agonist formulated as a solution for injection) and that its stability depends entirely on controlled temperature from manufacture to use. Refrigeration between 2°C and 8°C is required before first use. The freezer compartment must be avoided entirely: freezing irreversibly damages the solution, and a pen that has been frozen cannot simply be thawed and used. Once you have started using a pen or taken it out for a planned injection, a limited room-temperature window applies. That exact window is printed in the Patient Information Leaflet supplied with your medication; it is short enough that leaving the pen on a warm windowsill, in a hot car or in direct sunlight for an afternoon is a genuine risk, not a theoretical one. A question our prescribers hear most weeks is whether a Wegovy pen can go off if conditions are not maintained, and the honest answer is: check the leaflet, and if you are outside the stated window, do not use it. Erring on the side of caution with a biological medicine costs one pen; the alternative is less clear.

How to tell whether a Wegovy pen has gone bad

Wegovy solution should appear clear and colourless to slightly yellow. Before each injection, hold the pen up to a light source and look at the cartridge window. Any cloudiness, visible particles, or a change in colour beyond a faint yellow tint are signs that something is wrong, do not inject that dose. The same applies if the pen has been dropped and the cartridge is visibly damaged, or if you have any doubt about whether the pen was kept cold throughout transit and storage. It is worth knowing that a pen can degrade without any obvious visual change, particularly if it has been stored at the high end of room temperature for longer than the leaflet permits. That is why the time-and-temperature rules matter independently of what the solution looks like. Expiry dates printed on the pen label are a second, non-negotiable boundary: even a correctly refrigerated pen must not be used past that date. Semaglutide is a peptide molecule, and understanding how semaglutide affects your body includes recognising that its structure can break down with time, reducing how much active medicine each dose actually delivers. If your pen is near or past expiry and you are unsure whether to use it, contact your dispensing pharmacy before injecting.

Travelling and practical storage situations

Keeping Wegovy cold during travel is one of the most common storage challenges. A medical-grade cool bag or insulated case with an ice pack (not direct ice, which can freeze the pen) is the standard approach for journeys that exceed a few hours. Airline rules for carrying injectable medicines in hand luggage vary, but most airlines accept a letter from your prescriber or pharmacy confirming the medical need, something the service FAQ covers in more detail. At home, the fridge door is usually the warmest part, so the main compartment is preferable; keep the pen away from the back wall where it might inadvertently freeze. If your power goes out for several hours and your fridge warms above 8°C, treat that pen as potentially compromised: consult the Patient Information Leaflet's room-temperature guidance and note how long it was warm. If in doubt, contact your pharmacy. Wegovy is a prescription medicine, and advice on whether a specific pen is still usable is something a prescriber or pharmacist can give you directly, that is exactly what the aftercare team at a regulated service is there for. For a broader look at how Wegovy's risks and tolerability compare to its benefits, the semaglutide overview covers how it works and what to expect from treatment.

Disposal, replacement and getting the right support

A pen you decide not to use (because it has been left out too long, has passed its expiry date, or looks abnormal) should be disposed of safely. Used and unused pens alike should not go into household recycling or general waste. A sharps container is the correct route for used pens; your pharmacy or GP surgery can advise on local disposal options for unused ones. If you need a replacement pen because of a storage problem, contact your dispensing pharmacy promptly. Through a regulated service, a prescriber can review the situation and, where clinically appropriate, issue a replacement prescription. On the question of whether Wegovy is right for you in the first place, and what the evidence says about its benefits and risks, the decision sits with a GPhC-registered prescriber who can weigh your full clinical picture. Discount codes and social-media sellers sometimes surface offering injectable weight-loss medicines at prices that seem attractive, and patients who have started treatment sometimes report unexpected digestive side effects such as bad gas on Wegovy, which is another reason to have a verified clinical team to turn to; the MHRA has warned repeatedly about counterfeit pens, and storage conditions in unofficial supply chains are unknown by definition. The only safe route is a prescription from a clinician followed by dispensing through a pharmacy you can verify on the GPhC register. If you are thinking about starting Wegovy and want to understand what treatment through a clinician-led service involves, you can read more on the treatment options page, or start a free consultation to have a prescriber assess your suitability directly.