Wegovy out of the fridge for 24 hours: what to do next

You opened the fridge this morning and realised the pen had been sitting on the worktop all night

It happens more often than you might think, a late injection, a busy evening, a pen placed next to the kettle instead of back in the fridge. Perhaps it was a Bank Holiday Monday and the order arrived on Saturday, then sat out while you were away for the weekend. The good news is that Wegovy's storage rules account for exactly this kind of real-world situation.

According to the Mounjaro SmPC and equivalent Wegovy product information on the eMC, semaglutide injection pens can be stored at or below 30°C for a cumulative maximum of 28 days outside of refrigeration. A single overnight stretch of around 24 hours counts against that total, but it does not exceed it on its own. So if your pen has never previously been left out, you can read more about whether Wegovy is still safe to use after time out of the fridge, because a 24-hour spell at normal UK room temperature leaves you with up to 27 days' remaining room-temperature time before the pen must be discarded.

The key word is cumulative. Every time the pen leaves the fridge counts. If last week it sat out for four hours and this week it sat out overnight, you add those periods together. Keeping a simple note (even a sticky label on the pen cap with the date it was first removed from the fridge) makes this easy to track. Our detailed guide to keeping Wegovy correctly refrigerated at home covers exactly how to set that up.

What the pen should look like before you decide to use it

Time out of the fridge is only one part of the check. Before any injection, hold the pen up to the light and look at the solution. Wegovy should be clear and colourless or very faintly yellow, with no visible particles, cloudiness or discolouration. If the appearance has changed, put the cap back on and contact your pharmacist or prescriber before using it, do not inject it on the assumption it is probably fine.

Also consider where the pen was stored during those 24 hours. Room temperature in a UK kitchen in winter is very different from a car dashboard in summer. The 28-day rule applies at temperatures at or below 30°C. If the pen was anywhere warmer than that (a sunny windowsill, a warm car, near a radiator) the 28-day allowance may no longer apply, even if the total hours out of the fridge look acceptable on paper.

Similarly, a pen that has been frozen should never be used, even after thawing. Freezing damages the drug irreversibly. If you are unsure whether a pen got too cold (say, near the back of a fridge with a faulty thermostat), the same rule applies: check the appearance, check the leaflet, and ask a pharmacist if in doubt. The NHS medicines page for semaglutide reinforces that storage instructions must be followed carefully and that you should check with a pharmacist before using a pen that may have been stored incorrectly.

When to discard the pen and what to do next

There are three clear situations where the pen should be discarded rather than used. First, if the cumulative time out of the fridge has reached or exceeded 28 days. Second, if the pen was exposed to temperatures above 30°C, or was frozen at any point. Third, if the solution looks anything other than clear.

Discarding a dose you have already paid for is frustrating, but injecting a compromised pen carries a different kind of risk, reduced efficacy at best, and at worst an injection of degraded medicine that will not behave as expected. Dispose of the unused pen in a sharps container and contact your prescriber to discuss what to do about your next injection timing.

If you need a replacement pen, the question of when to inject and whether to stay on the same dose or adjust is one your prescriber should answer, do not guess at the interval, because restarting after an unplanned gap has its own guidance in the Patient Information Leaflet. Our broader guide to semaglutide storage outside of the fridge explains the wider rules if you are comparing across pen types.

Keeping track going forward: a practical approach

The 28-day out-of-fridge allowance exists precisely so that Wegovy is usable in normal life, travel, work trips, or simply the occasional missed put-away. Our full guide to Wegovy out of the fridge walks through exactly how to track your total, not just the most recent stint. A few habits make this straightforward: write the first-removed date on the pen (a small sticky note or a marker on the cap works), store it in the fridge door where it is easy to see and grab, and check the appearance before every dose regardless of how recently it was filled.

For context on how this sits within the broader picture of your treatment, our overview of Wegovy in the UK covers the full scope of how the medicine works, what the licensed schedule looks like, and what to expect from treatment, including the lifestyle elements that sit alongside the injection. If cost or access is a consideration too, the current Wegovy pricing guide sets out what private treatment involves without any hidden fees.

Managing this kind of detail well is part of why having a prescriber you can actually reach matters. At nume, every patient has access to priority aftercare seven days a week, so if you open your fridge on a Saturday morning with a question about your pen, you are not waiting until Monday for an answer. If you have not yet started treatment and are considering Wegovy, check your eligibility with our prescribers.