Semaglutide storage conditions: keeping your Wegovy pen safe and effective

Step 1, When your pen arrives: straight to the fridge

Wegovy arrives cold for a reason. The active ingredient, semaglutide, is a protein-based molecule that begins to break down if it sits at the wrong temperature for too long. When your delivery arrives, move the pens into the fridge promptly. They should sit between 2°C and 8°C, the same range as most standard household fridges.

Position matters more than most people realise. Pens stored right next to the freezer compartment, or pressed against the back wall of a fridge that runs cold, risk freezing. A frozen pen cannot be thawed and used, the structure of the medicine is altered and the pen must be discarded. The middle shelf or the fridge door (which tends to be slightly warmer) is usually the safest spot, though a thermometer is the only reliable check if you are unsure.

Keep the pen in its original packaging until you are ready to use it. The carton provides an additional layer of light protection. For a closer look at general fridge practices for injectable medicines, our Wegovy fridge storage guidance covers the specifics in more detail, and if you want a broader overview of how Wegovy should be stored across its full shelf life, that page brings everything together in one place. The NHS semaglutide medicines page also sets out the storage requirements in plain language.

Step 2, Taking a pen out of the fridge: the room-temperature window

You do not need to inject a cold pen. Many people find the injection more comfortable at room temperature, and there is no clinical reason to use the pen straight from the fridge. What matters is that once a pen leaves refrigeration, the clock starts on a limited room-temperature window.

The exact number of days varies between the standard Wegovy injection pen and the newer single-dose 7.2mg pen approved by the MHRA in April 2026. Rather than quote a figure here that could become outdated or be misapplied to the wrong format, we would always direct you to the Patient Information Leaflet inside your pack, the number is printed clearly, and it is the number that applies to your specific pen.

During room-temperature storage, keep the pen below 30°C and away from direct sunlight. A windowsill in summer or a car dashboard in warm weather are exactly the wrong places. If you are planning to travel, our page on semaglutide storage temperatures walks through what to consider when you're away from home, and our dedicated guide to semaglutide injection storage goes into further detail on keeping your pen safe between doses.

One misconception worth clearing up gently: some people assume that popping the pen back into the fridge resets the clock. It doesn't. Once removed, the room-temperature days count down regardless of whether the pen moves in and out of the fridge during that period. The total time outside of the 2°C–8°C range is what matters.

Step 3, During use: handling and checking your pen

Before each injection, take a moment to inspect the pen. The solution in a Wegovy cartridge should be clear and colourless; if it appears cloudy, discoloured, or contains visible particles, do not use it. The same applies if the pen looks physically damaged, a cracked casing or a needle that has been bent can affect both safety and the accuracy of the dose.

Replace the cap after every use. It protects the needle from contamination and shields the cartridge from light between doses. Each pen contains four weekly doses; it is not a single-shot device, so the pen lives in and out of the fridge across the course of a month.

If you are storing multiple pens, keep them organised so the earliest expiry date is used first. The expiry date is printed on both the pen and the outer carton. An expired pen should be treated like any other medicine past its date, not used and disposed of safely. Our guide to setting up your Wegovy pen covers the full injection process if you would like a step-by-step refresher on technique alongside storage. For safe disposal, a 1-litre sharps container is the correct way to discard used needles and pens in the UK.

Step 4 (Getting clinical support when something goes wrong

Storage questions that fall outside the leaflet's scope) a power cut that left the fridge off overnight, a pen that was accidentally left in a hot car, or uncertainty about a pen that may have frozen, are exactly the kind of thing your prescriber or pharmacist is there for. Do not guess.

If you are on treatment with a service like nume, aftercare support is available seven days a week precisely for moments like these. Reporting any suspected quality issue with a medicine is also possible through the MHRA's Yellow Card scheme, which accepts reports from patients as well as clinicians.

If you are considering starting treatment or are looking at how injectable weight-loss medicines compare, a free consultation with our prescribers is the right starting point. They review your answers the same day (a real clinician, not an automated filter) and can discuss which option fits your circumstances before any prescription is written.