Do you need to store Wegovy in the fridge — and what happens if you don't?

The misconception: 'It doesn't matter much if it warms up for a bit'

This is probably the most common mistake people make with injectable weight-loss medicines. Because the pen is pre-filled and the injection happens weekly rather than daily, there's a tendency to treat the pen more casually than you would, say, a course of antibiotics you're taking every morning. The logic feels reasonable: one day out of the fridge, surely, is fine.

Partly it is. The Patient Information Leaflet for Wegovy does allow a room-temperature window, and that provision exists precisely because real life isn't a controlled refrigerator. But the window is finite, it applies only to temperatures up to 30°C, and it is not a rolling allowance you can reset each time the pen goes back in the fridge. Once that time has elapsed at room temperature, the pen should not be used even if it still looks and feels normal. Semaglutide degrades at temperatures outside the recommended range without giving you any visible warning, there's no colour change, no smell, no obvious sign. You would simply be injecting a less potent or inactive medicine.

The NHS semaglutide medicines page is clear that storage must follow the instructions in the leaflet that comes with your pen. If you're unsure whether your pen has been stored correctly, contact your prescriber before using it. On the broader question of whether Wegovy needs to stay in the fridge at all stages of treatment, the consistent answer from official guidance is yes, until it doesn't, and the PIL tells you exactly when that exception applies.

What the room-temperature rule actually means in practice

The short-term room-temperature allowance is there for situations like travel, a hotel stay, or the gap between a delivery arriving and you getting home. It is not a loophole for storing the pen in a bedroom drawer full-time. Always read the current version of your Patient Information Leaflet for the precise number of days and the maximum temperature, because these figures are the legally authorised instructions for your specific product.

A few practical points that often come up. First, 30°C is the upper limit, a warm car parked in direct sun can reach well above that, and a pen left on a dashboard in summer almost certainly has. Second, if you receive a delivery during a heatwave and the pen sat in a DPD van for several hours, that exposure counts against the allowance. Third, the question of whether you have to store Wegovy in the fridge is addressed in detail on its own page, where you can also find guidance on when the room-temperature clock starts and how to keep a note of that date.

One thing people often do not think about until it catches them: holiday timings. If your monthly pen arrives the week before you fly, and you're away for ten days, you'll want to confirm whether your accommodation has a suitable fridge before you leave. Getting this wrong could mean losing a whole pen, not a small inconvenience given the cost of private treatment. Our Wegovy price comparison guide has context on what UK private treatment costs, which underlines why protecting each pen matters.

For further detail on how the storage window interacts with weekly dosing schedules, the how long you can store Wegovy in the fridge page covers this more closely.

Freezing, light and what else damages the pen

Freezing is an absolute line. If a pen has frozen (even briefly) it must not be used. The medicine inside can be damaged by ice crystal formation in ways that are not visible from the outside. This applies even if the pen thaws back to room temperature and looks completely normal. The Wegovy SmPC on the electronic Medicines Compendium specifies that frozen medicine must be discarded, not used. The same applies to pens that have been exposed to temperatures significantly above 30°C for any meaningful period.

Light exposure is a lesser-known concern. Wegovy pens should be kept in their original carton until use, partly because the packaging provides some protection against light degradation. If you've been storing your pen without the box, it's not necessarily ruined, but it is worth keeping it in a dark spot in the fridge rather than in the door where it gets light every time the fridge opens.

You'll also want to keep the pen away from the freezer compartment of your fridge if that part runs colder than 2°C, which some do. Place it on a middle shelf rather than at the very back, where some fridges get close to freezing.

Questions about this, especially if something has gone wrong with a pen, are exactly the kind of thing our prescribers are there for. You can read more about Wegovy as a treatment and how the overall programme works, or look at how semaglutide storage rules apply more broadly across the medicine in different formulations. If you are thinking about starting treatment and want to understand what clinical assessment involves, checking your eligibility with our prescribers is the next step.