How long does Wegovy last in the fridge unopened — and what actually goes wrong

The myth worth correcting first: 'if it looks fine, it's fine'

The most common misconception about semaglutide storage is that visual inspection is a reliable safety check. It isn't. A pen that has been frozen and thawed, or held at the wrong temperature for too long, can appear completely normal (clear, colourless liquid, no visible particles) and still be degraded. Protein-based medicines like semaglutide are sensitive to temperature at a molecular level. The damage is invisible to the naked eye. This is precisely why the storage conditions stated in the SmPC exist, and why the NHS semaglutide medicines page directs patients to the Patient Information Leaflet rather than relying on appearance alone.

So: how long does unopened Wegovy last in the fridge? Until the expiry date on the outer carton, provided the pen has been stored uninterrupted at 2–8°C and has never been frozen. That caveat (never frozen) carries more weight than most people give it, and if you want a full breakdown of the timeframes involved, our guide on how long Wegovy lasts in the fridge covers the detail. Fridge shelves near the ice compartment or the back wall can dip below 0°C if the thermostat is poorly calibrated. Keep Wegovy pens on a middle or lower shelf, away from the cooling element, and check your fridge with a thermometer if you have any doubt.

One practical note: the expiry date on the individual pen and the date on the outer carton should match. If there is any discrepancy, contact the dispensing pharmacy before using the pen. A question our prescribers hear regularly is whether a pen 'close to expiry' is still worth using, the answer is yes, provided it has been stored correctly and the date has not passed.

What the fridge conditions actually need to look like

The target range is 2–8°C, which is standard domestic refrigeration. Most household fridges operate within this band when the thermostat is set to mid-range, but real temperatures vary by position inside the fridge. The door shelf, for example, experiences the most temperature fluctuation every time the door opens. That is not the right place for a Wegovy pen. A central shelf or the salad drawer (which tends to be buffered from temperature swings) is safer.

Freezing is the one irreversible error. Semaglutide pens must not be frozen; if ice crystals form inside the cartridge, the medicine is damaged. This applies whether the pen froze briefly or for an extended period. There is no visual test that reliably distinguishes a frozen-and-thawed pen from an intact one, which loops back to the myth above. If you know or suspect a pen has frozen, discard it. For guidance on what to do if a pen has been left at room temperature rather than frozen, the specific rules on that scenario are covered in the separate page on Wegovy left outside the fridge.

Protecting the pen from light is a secondary but real consideration. The outer carton provides the necessary protection during fridge storage. Remove the pen from the carton only when you are about to use it, do not store open pens loose in the fridge door without any packaging.

How long unopened semaglutide lasts versus once a pen is in use

It is worth being clear that the rules for an unopened pen and an in-use pen are different, and confusing the two is a common source of anxiety. How long an unopened pen lasts in the fridge is governed by the expiry date printed on the carton, assuming correct cold storage throughout, and our dedicated page on unopened semaglutide left out of the fridge explains what happens when that cold chain is interrupted before a pen has been used. How long an opened pen remains usable is governed by a shorter, fixed window stated in the Patient Information Leaflet, that figure is not repeated here because it is a dosing/instructions matter that belongs with your prescriber and the leaflet. If you want to understand the difference fully, the page on opened Wegovy pens addresses that question directly.

For those wondering about multiple pens (for example, if you have received a month's supply and will only use one pen in the coming weeks) all remaining pens should remain in the fridge, in their cartons, until the date they are due to be used. There is no benefit to bringing pens to room temperature early. The storage guide covering multiple pens has more detail on batch storage.

The Wegovy SmPC, held on the electronic Medicines Compendium (eMC), is the authoritative source for storage parameters and should be your first reference for any specific detail not covered in your Patient Information Leaflet. Pharmacists at a GPhC-registered pharmacy can also clarify storage queries at the point of dispensing.

When storage concerns mean the medicine needs clinical review

If you are uncertain whether a pen has been compromised, do not inject it. Contact the dispensing pharmacy in the first instance. If the pen was supplied through a regulated pharmacy, the clinical team can advise on whether a replacement is needed and how to dispose of the affected pen safely. You can also raise concerns with our team through the contact page.

It is worth being honest about how frustrating this situation is: storage errors usually happen through no fault of the patient (a fridge malfunction, a delivery delay, a temporary power cut) and the idea of discarding a pen that cost money feels wrong. But injecting a potentially degraded prescription medicine is the greater risk. An ineffective dose is the best-case outcome; an unpredictable one is the concern.

If you are at the stage of exploring semaglutide treatment rather than managing an existing prescription, the weight-loss treatment overview explains who the injection is licensed for, and our clinical team, led by our clinical lead, carries out same-day review of every consultation. Check your eligibility when you are ready.