Wegovy temperature requirements: keeping your semaglutide effective

What the prescribing information says about refrigeration

The Wegovy Summary of Product Characteristics (the authoritative clinical document published on the electronic Medicines Compendium (eMC)) specifies refrigerated storage at 2°C to 8°C as the default condition throughout the pen's shelf life. This is not a cautious estimate; it is the temperature range under which the stability of semaglutide was confirmed during the medicine's regulatory assessment by the MHRA before UK approval was granted.

Freezing is explicitly prohibited. A pen stored in the freezer compartment, or directly against the back of a fridge where temperatures can dip below zero, should be discarded. Ice crystals can form within the solution and alter its properties in ways that are not visible to the naked eye. The pen may look fine and still inject smoothly, that is why the leaflet's guidance is not optional.

Light is a second hazard. Semaglutide is photosensitive, which is why pens come in an opaque carton. Keeping a pen on a windowsill or in a bag that sits in direct sun is enough to compromise it, particularly over several days. The original packaging exists for a reason: use it.

For the precise storage window that applies to your specific pen and batch, always read the Wegovy SmPC on the eMC (or the Patient Information Leaflet inside your box) rather than relying on a summary elsewhere. Small details can vary by formulation update.

The room-temperature allowance: what you actually need to know

The prescribing information does allow Wegovy pens to be kept at room temperature for a defined period, which is useful for travel, days away from home, or simply not wanting to inject a refrigerator-cold pen. The permitted duration is printed in your Patient Information Leaflet.

A few practical points follow from this. First, the room-temperature window is a one-time allowance, not a rolling one, once a pen has been out of the fridge and then returned, the clock does not reset. Second, room temperature in the UK context means below 30°C; on a warm summer day a car interior, a sunny bag pocket, or a shelf near a radiator can easily exceed this. Third, the instruction says "below 30°C", not "up to 30°C for as long as you like", think of it as an emergency or travel allowance rather than an alternative to refrigeration.

If you are travelling and need guidance on managing your pens away from a fridge for longer periods, the wegovy overview page covers the broader picture of treatment logistics, and your prescriber at the nume clinical team can advise on your specific itinerary. Insulated travel cases designed for injectable medicines are widely available and worth considering for longer trips.

The underlying reason storage matters as much as it does is straightforward: semaglutide is a peptide, a biological molecule. Unlike a simple salt or chemical compound, peptides are vulnerable to heat, cold extremes and light in ways that can reduce their potency without producing any visible change. You cannot tell by looking at a pen whether the solution inside has degraded.

What to do if you think your pen may have been stored incorrectly

This is the question our prescribers hear regularly, and it is a sensible one to ask. The honest answer is: if you are uncertain, do not inject. A wasted pen is a cost; an injection of degraded medicine is a clinical problem, either it will be less effective than expected, or in the worst case the solution may have changed in ways that carry a small risk of reaction.

Contact your pharmacist or prescriber first. At nume, aftercare support runs seven days a week precisely for situations like this. Describe when the pen came out of the fridge, what temperature it was likely exposed to, and for how long. A prescriber can help you assess whether the pen is within the permitted window or whether a replacement is needed.

It is also worth knowing that side effects should be reported to the MHRA via the Yellow Card scheme, and if you suspect your pen may have been tampered with or is not genuine, the Yellow Card service accepts reports of suspect products too. Anyone starting Wegovy through a clinically supervised route at a GPhC-registered pharmacy can at least be confident their pens arrived from the licensed UK supply chain, refrigerated throughout transit in appropriate packaging.

If you are considering starting treatment and want to understand the full eligibility picture first, our page on the Wegovy BMI requirement sets out who the medicine is licensed for in the UK, including how body weight criteria interact with other health factors. If you are also weighing up semaglutide more broadly, you may find it helpful to read about the semaglutide BMI requirements that apply across the different formulations available in the UK. For a complete overview of eligibility criteria beyond BMI alone, the page covering what the requirements for Wegovy are brings together the clinical, medical history, and lifestyle factors that prescribers consider. For a broader look at weight-loss treatment options, the weight-loss overview covers how different medicines compare and what clinical assessment involves.