How Long Does Wegovy Last Unrefrigerated — and What Happens if It Does?

The 28-day rule: where it comes from and what it actually means

The Wegovy SmPC (available via the electronic Medicines Compendium) specifies that pens may be stored at room temperature, up to 30°C, for a maximum of 28 days. That figure comes from Novo Nordisk's stability testing, which maps how rapidly the active ingredient semaglutide degrades under real-world conditions. At temperatures above 30°C (a hot car, a sunny windowsill in July, a beach bag in direct sun) degradation accelerates and the pen should be treated as beyond its usable life even if fewer than 28 days have passed.

The count starts the moment the pen leaves the fridge, not the moment you give your first injection. If your pen sat in a warm delivery bag for two days before you opened the box, those two days count. Practically speaking, this means tracking the exact date you took the pen out of refrigerated storage is genuinely worth doing, a note in your phone calendar takes seconds and removes any guesswork later.

Returning the pen to the fridge partway through the 28-day window does not extend it. The clock keeps running regardless of whether the pen moves back and forth. Some patients assume cold storage resets things; it does not, and the SmPC is clear on this point.

What goes wrong when semaglutide is stored incorrectly

Semaglutide is a peptide hormone, and like most biological medicines it is sensitive to physical conditions in ways that are not always visible. A pen exposed to excessive heat or freezing temperatures may look completely normal (clear liquid, no particles, no change in colour) yet still deliver a reduced or unpredictable dose because the active molecule has partially denatured.

Freezing is a particular risk worth flagging. If a Wegovy pen has been frozen, even accidentally (the back of a fridge drawer, a courier van in January), it must not be used. Thawing does not restore a frozen peptide to its original state. The NHS medicines page for semaglutide advises keeping pens away from the freezer compartment and not using a pen that has frozen.

Exposure to direct sunlight is the other common problem. UV light breaks down biological molecules faster than ambient warmth alone, which is why the pen should be kept in its original carton when out of the fridge, not just for tidiness, but for protection. If you've had your pen rattling around loose in a bag in direct sun for a day, that is worth raising with your prescriber before injecting, and our guidance on how long Wegovy can safely be kept unrefrigerated explains the limits in more detail.

None of these risks mean Wegovy is fragile in normal use. Millions of people carry pens in handbags and coat pockets for short periods without issue. The guidance exists to mark the outer limits, not to create anxiety about ordinary handling.

Travelling with Wegovy: planning for the 28-day window

Travel is where most people run into storage questions. For short trips, the 28-day room-temperature window is usually generous enough that no special equipment is needed beyond keeping the pen out of heat and sunlight. A cool bag or insulated pouch is a sensible precaution for longer journeys or hot climates, even though the pen does not need to be kept cold, it needs to be kept below 30°C, which in a 35°C summer in southern Europe means a little planning. There is more detail on managing this across longer journeys in our guidance on travelling with Wegovy when refrigeration is not available.

For trips longer than 28 days, the question changes. If you are abroad for six weeks, you cannot simply leave the pen at room temperature throughout, you need access to a fridge at your destination or a clinical conversation about timing your supply. Arriving with a freshly dispensed pen before departure keeps the most days available. It is worth reading about how long Wegovy can be kept refrigerated before travel so you understand the full picture at both ends of the journey.

Airport security is a separate but related question. Wegovy pens are permitted in hand luggage as a medical device; carrying a copy of your prescription or a letter from your prescriber removes any ambiguity at the gate. Our Wegovy treatment overview covers the broader practical aspects of managing the medicine once prescribed.

Disposing of a pen that has exceeded its storage limit

If a pen has been unrefrigerated for more than 28 days, or was exposed to temperatures above 30°C or to freezing, the right course is disposal rather than use. Using a degraded pen risks a less effective dose or, in rare cases, particulate contamination, so the cautious choice is always disposal when storage conditions are in doubt.

Wegovy pens are sharps and should not go in the household bin. A sharps container is the correct receptacle; once full, these can be returned to a local pharmacy or a council sharps disposal point. Most community pharmacies will accept them free of charge. If you have had to discard an unused pen, contact your prescriber to discuss your next supply, losing a pen to storage error is not something to manage alone, and your prescriber can advise on timing.

If you are thinking about starting Wegovy or managing your ongoing treatment through a clinician-led service, the cost of Wegovy through a private pharmacy is a practical consideration many people weigh at this stage too, it is worth understanding what a legitimate prescription includes before comparing prices.

Our prescribers are available seven days a week. Speak to our prescribers if you have questions about your storage situation or want to begin a consultation.