How Long Does Semaglutide Last in the Freezer — and Should It Go There at All?

The misconception: freezing preserves semaglutide longer

It is understandable to assume that a freezer, which extends the life of most perishable things, would do the same for an expensive medicine. With Wegovy, the opposite is true. Semaglutide is a peptide (a chain of amino acids) and peptide medicines are structurally sensitive to the ice-crystal formation that happens during freezing. Once those crystals form inside the solution, the three-dimensional shape of the active molecule is disrupted in a way that cannot be reversed by thawing. A pen that has been frozen and then returned to room temperature may look normal, but the medicine it contains is no longer reliable.

The NHS medicines information for semaglutide is clear that the injection should be stored in a refrigerator and must not be frozen. This is not a precautionary overstatement; it reflects the physical chemistry of the medicine.

If you are wondering about the broader picture of how long semaglutide lasts in the body once injected, that is a separate question covered in detail on our page about how long semaglutide lasts in the body.

What correct Wegovy storage actually looks like day to day

Wegovy pens should sit in a refrigerator at 2–8°C, away from the freezer compartment and away from the back wall of the fridge, where temperatures can dip below 2°C on some appliances. The fridge door shelf (convenient as it sounds) is one of the riskier spots because the temperature there fluctuates every time the door opens. A middle shelf, in the original packaging, is preferable.

Once a pen has been removed from the fridge, a room-temperature window begins. The precise duration of that window is printed in the Patient Information Leaflet that comes with your treatment; always follow that figure rather than a number found online, because it is the one specific to your product batch and pen format. The newer single-dose 7.2mg Wegovy pen, approved by the MHRA on 14 April 2026, has its own SmPC, and the room-temperature rules for it should be read from the relevant section of the electronic Medicines Compendium (eMC) or the leaflet in the box.

One practical note our prescribers raise regularly: travel cooler packs, if placed directly against the pen in a cool bag, can freeze the outer surface of the cartridge even when the air inside the bag feels merely cool. Keep an ice pack separated from the pen by a layer of insulating material.

How to tell whether a pen has been frozen by accident

The solution in a Wegovy pen is colourless and clear. If you hold the pen up to light and the liquid looks cloudy, has visible particles floating in it, or has taken on any colour, do not use it. These are the signs most commonly associated with freeze damage, though they can also indicate other forms of degradation.

A pen returned to 2–8°C after accidental brief freezing will thaw, but thawing does not restore the medicine's integrity. The damage is done at the molecular level, not the visible one, which is why the instruction to discard a frozen pen applies even when the solution looks clear after thawing. When in doubt, contact a pharmacist. The cost of discarding one pen is genuinely preferable to injecting a degraded medicine that may be ineffective or, in theory, cause unexpected reactions.

If you are also thinking about timelines in a different sense (how quickly Wegovy begins working after a correctly stored and administered dose) our page on how long Wegovy takes to work covers that in full. And for context on the medicine's half-life and how long it remains active between weekly injections, the page on how long semaglutide stays in your system is worth reading alongside this one.

What to do if you have already used a frozen pen, and when to get medical help

If you realise after injecting that the pen had previously been frozen, the most important immediate action is to contact a pharmacist or your prescriber. In most cases the practical concern is that the dose was ineffective rather than directly harmful, but you should not make that assumption alone. Note the date, which dose it was, and whether you noticed anything unusual about the solution before you injected.

Separately, if you experience any new or unusual symptoms after an injection (particularly severe stomach pain, signs of an allergic reaction such as swelling of the face or throat, or significant nausea and vomiting that prevents you from keeping fluids down) seek medical help promptly. These signs warrant attention regardless of storage history. You can report any suspected problem with a medicine, including a suspected quality defect, through the MHRA Yellow Card scheme.

Wegovy is a prescription-only medicine, and the clinical oversight that comes with a legitimate private prescription includes exactly this kind of aftercare support. If you are already on treatment through a regulated service and have a storage concern, the right call is to the pharmacy or prescriber who issued it. If you are considering starting treatment and want to understand more about what responsible private prescribing looks like, our Wegovy overview explains how the process works. You can also explore what a full course of privately prescribed treatment typically costs (consultation, prescription, delivery and aftercare included) on our Wegovy pricing page. When you are ready, you can check your eligibility with our clinical team.