Is semaglutide supposed to be refrigerated — and what happens if it isn't?

Does semaglutide always have to live in the fridge?

Before first use, yes. Wegovy pens should be kept in a refrigerator at 2°C to 8°C, that is the storage condition under which the medicine has been shown to remain stable. The fridge door is a perfectly reasonable spot; just make sure the pen is not touching the back wall of the fridge, where temperatures can dip low enough to cause ice crystals to form.

Once you have started using a pen, the picture changes slightly. There is a defined period during which an in-use pen may be kept at room temperature, and the Wegovy SmPC on the eMC states this exactly. We deliberately do not print that number here, because the window can differ between product batches and presentations, and the leaflet that came with your specific pen is the only version you should rely on.

If storage outside the fridge is something you need regularly (for travel, for work, or just because your fridge situation is complicated) our page on using semaglutide when it has not been refrigerated covers the practical questions in more detail. And if Wegovy's storage conditions are something you want to compare across injections more broadly, our guide to semaglutide injections gives the wider picture.

The one rule with no exceptions: if a pen has been frozen, discard it. Freezing breaks down the protein structure of the medicine, and thawing it back to room temperature does not restore what was lost.

What actually happens if semaglutide gets too warm or too cold?

This is the question a lot of people feel slightly embarrassed to ask, particularly if they suspect a pen has already been left out longer than it should have been. It is a very sensible thing to want to know.

Semaglutide is a peptide molecule. Sustained heat causes it to degrade, the active compound breaks down into forms that are no longer effective. A pen that looks entirely normal may deliver a reduced dose, or no therapeutic effect at all. You would have no way of knowing from appearance alone, because degraded semaglutide does not change colour or become cloudy the way some other injectables do.

Cold damage is, in one sense, more obvious: a frozen-then-thawed pen may show small particles or cloudiness, and the NHS semaglutide medicines page is clear that the solution should be colourless and clear before each use. If it is not, do not inject it. Contact your pharmacist.

The practical upshot: a pen left on a sunny windowsill for a day is not automatically ruined, but a pen left in a hot car or a warm bathroom cabinet for an extended period probably is. When in doubt, the right call is always to check with a prescriber or pharmacist rather than inject and hope for the best.

How should you handle storage on a longer trip?

Travel is where semaglutide storage causes the most stress, and that is understandable, you are outside your usual routine, often in environments you cannot control. The good news is that the room-temperature window built into the licence exists precisely to cover the kind of short-term variation that real life involves.

For a flight, keep your pen in your hand luggage, not in checked baggage in the hold. Aircraft cargo holds routinely drop well below freezing. Airline passengers are permitted to carry prescription medicines in the cabin with appropriate documentation, a dispensing label from a GPhC-registered pharmacy is usually sufficient, and you can carry a letter from your prescriber if you prefer something more formal.

An insulated travel case can buffer against heat, but avoid ice packs that are in direct contact with the pen. The goal is stable cool, not frozen.

If you are travelling for longer than the room-temperature window allows, access to a hotel mini-fridge or similar is worth planning for. Our page on how long Wegovy can be refrigerated picks up the question of shelf life once a pen is in the fridge. For the broader question of whether the storage rules differ between Wegovy and other injections, our storage overview for Wegovy is a useful companion read.

Wherever you are going, take your Patient Information Leaflet with you. It is the single most reliable reference for your specific product.

What should you do if you think your semaglutide has been stored incorrectly?

Do not inject it until you have spoken to someone who can advise you properly. That means your prescriber or a pharmacist, not a forum, not a rough guess based on how the pen looks.

If you are a patient with a nume prescription and you have a question about a pen that may have been affected, our aftercare team is available seven days a week via the contact page. Prescribers can advise on whether to use the pen, discard it, or request a replacement. A pen that has been compromised is a clinical matter, not a minor inconvenience.

More broadly, if you are thinking about starting semaglutide and want to understand exactly what the medicine involves before you commit, looking at our Wegovy treatment page and the weight loss overview is a good place to begin. The Wegovy pricing page sets out what is included in the cost. And when you are ready to talk to a prescriber, checking your eligibility is the natural first step.

One honest note: if any of this feels like a lot of detail for something you just assumed would be simple, you are not alone. Storage questions are among the most common things our prescribers are asked, particularly by people new to injectable treatment. Getting it right matters, so asking is the right instinct.