Where do you store semaglutide — and what happens if you get it wrong?

Does semaglutide always need to go in the fridge?

Before you use a pen for the first time, yes: refrigeration at 2–8°C is required. The fridge door shelf is fine for most household fridges, it stays within range, and the pen is easy to find. What the door shelf is not good for is anywhere near the freezer drawer or the vent at the back of the main compartment, where temperatures can dip below zero without warning. Freezing deactivates the active ingredient. A frozen pen looks perfectly normal; there is no visible sign that the medicine has been compromised. That is why the rule matters more than it might seem.

Keep the pen in its original carton. This is not just tidy habit, the carton shields the pen from light, which can degrade semaglutide over time. If you store it loose in the fridge door, move it back into the box between doses.

The NHS medicines page for semaglutide confirms the 2–8°C storage requirement and advises keeping the medicine away from direct sunlight. For full storage detail specific to your pen format, the summary of product characteristics on the eMC is the definitive reference, your Patient Information Leaflet reproduces the key points.

Where do you store semaglutide once you've started using a pen?

An in-use pen can be stored either in the refrigerator or at room temperature below a specified maximum, for a defined period. The specific figures (how many days, and the temperature ceiling) appear in your product's Patient Information Leaflet, and our page on how you store semaglutide covers those practical details in full. Different presentations of semaglutide (the standard Wegovy injection pen and the newer 7.2mg single-dose pen) may carry slightly different instructions, so always go back to the leaflet that came with your pen rather than relying on a general number you've seen elsewhere.

Practically speaking, most people find it simplest to keep the pen in the fridge throughout. There is no clinical reason to take it out early; it does not need to warm up before injecting. If you need to carry a pen with you (travelling, or injecting away from home) room-temperature storage for the permitted window is what the licence allows. You can read more about the specific duration questions on our page covering how long semaglutide can be stored.

One thing worth knowing: if you are considering switching from the injection pen to a different format, storage rules can differ. Our Wegovy overview covers the full product range and what to expect from each.

What about travel, gym bags, and leaving a pen in a warm car?

A pen left in a car on a warm day can easily exceed safe storage temperatures, even in British summer. The inside of a parked car can reach well above the permitted room-temperature limit within minutes. The same applies to a gym bag left in direct sunlight or near a radiator. If you are not sure whether a pen has been stored correctly, the safe answer is not to use it and to contact your pharmacy.

For travel, a small insulated cool bag (the kind sold for insulin) keeps pens within range without freezing. Airline hold luggage can freeze, so keep pens in your carry-on. For longer trips, details on managing storage and what to do if a dose is missed are questions best put directly to your prescriber; the answer will depend on how long you've been on treatment and which dose you're using.

If you are new to injecting and want to understand how injection sites and technique interact with storage and handling, our guide on where to inject semaglutide covers that in full. And if you are researching Wegovy before starting, the weight-loss treatment overview sets out how the process works at nume.

What should you do if a pen has been stored incorrectly?

Do not inject a pen that you believe may have been frozen, left in heat, or stored outside the permitted conditions. A compromised pen may still look normal, the liquid may be clear, the pen may feel fine. The degradation is not visible. It is also worth knowing that if you notice anything unexpected at the injection site after using your pen, our page on what to do if you see blood after a Wegovy injection explains what is normal and when to seek further advice.

Contact your pharmacy. At nume, aftercare support is available seven days a week, so you are not waiting until Monday if something has gone wrong over the weekend. Your prescriber can advise whether a replacement is appropriate. Separately, if you ever have concerns about a medicine you have received (from any source) you can report it via the MHRA Yellow Card scheme, which accepts reports from patients as well as clinicians.

For a fuller walkthrough of the storage steps from pen arrival through to injection, our guide on how to store a semaglutide injection goes through each stage in order. And if you are still at the stage of deciding whether semaglutide is the right option for you, our prescribers can discuss that properly during a free consultation, see below.