How Long Do Wegovy Pens Last — and How to Store Them Properly

You open the box and realise you're not sure how long this pen is good for

It's a reasonable moment of uncertainty. The pen has been sitting in the fridge, you've started your first injection, and you want to know whether the next three doses are still going to be effective when their weeks come around. The short answer: yes, if you've kept the pen cold and haven't accidentally frozen it.

Unopened Wegovy pens must be stored in a refrigerator at 2–8°C from the moment you receive them. The NHS guidance on semaglutide is clear on this point, freezing destroys the medicine, and a pen that has been frozen should not be used. Keep them away from the freezer compartment and from the back of the fridge shelf where temperatures can dip unpredictably. The vegetable drawer or the fridge door (as long as it's stable and not frequently left open) works well for most people.

Once you've given yourself the first injection from a pen, the clock changes. The medicine can be kept at room temperature, below 30°C, for a defined period, and if you want a precise breakdown of exactly how many days you have and what affects that window, a dedicated page covering how long one pen of Wegovy lasts sets it out clearly. Temperatures above 30°C accelerate degradation; direct sunlight does too. Don't leave the pen on a windowsill or in a warm car.

For a thorough look at how refrigeration requirements work across the full treatment period, the full guide to Wegovy pen fridge storage covers the specifics in detail.

What 'four doses per pen' actually means for your supply calendar

Each pre-filled Wegovy pen is designed for four weekly injections. You press the device against the injection site, hear the click, hold for the specified time, and then recap the pen and return it to safe storage. One pen, used correctly, takes you through a full four-week period.

The practical implication is that your supply planning should run in four-week cycles. If you order late or a delivery is delayed, you will face a gap, and interrupting treatment without clinical guidance is not ideal. Our prescribers review every repeat order before it's dispensed, which is also the moment to flag any concerns about dosing, side effects, or supply timing.

People sometimes ask whether they can split doses or use a partial pen more slowly to stretch supply. The answer is no: each dose is pre-set by the device mechanism, and the pen is not designed for partial injection. Trying to adjust this risks inaccurate dosing and potential device failure. If you're worried about a gap in supply, speak to your prescriber rather than altering how you use the pen.

If you want a clear account of exactly how a single pen is structured and used, the page on how long a Wegovy pen lasts walks through the device in more practical detail. Questions about needle size and technique are covered separately on our Wegovy needle length guide.

Expiry dates, degraded pens, and when not to inject

Every Wegovy pen carries a printed expiry date. Do not use a pen past that date, the active semaglutide molecule can degrade over time, and an expired pen may deliver less medicine than intended, or none at all. Check the date when a new supply arrives, and if the expiry is close, flag it with your pharmacy immediately.

Signs that a pen may have been stored incorrectly include: a cloudy or discoloured solution (it should be clear and colourless to slightly yellow), visible particles, or a pen that has clearly been frozen (ice crystals or unusual viscosity). The NHS patient information on semaglutide advises not to use the medicine if the solution looks abnormal in any way. When in doubt, contact your pharmacy.

Sharps disposal matters too. Used Wegovy pens are clinical waste. A sharps container keeps used pens safely contained until they can be disposed of through your local council's sharps collection scheme. Never put used pens in household recycling or general waste.

The Wegovy pen is a prescription-only medicine, if you're still exploring your options or want to understand the full treatment picture before starting, the Wegovy treatment overview is a good starting point, and our weight loss treatment page sets out what's available through a regulated UK private pharmacy.

Travelling, routines, and the practical day-to-day

A question our prescribers hear regularly: what happens to the pen when you travel? The same rules apply, but logistics get trickier. Keeping the pen refrigerated on a long journey requires a cool bag with an ice pack, not direct contact with ice. Cabin pressure on flights doesn't affect the medicine, but temperature in the hold can, carry it in hand luggage.

Many people settle into a weekly injection routine anchored to something fixed: Sunday evening after dinner, or Monday morning while the kettle boils. Consistency matters because Wegovy is designed as a steady-state weekly treatment; injecting at roughly the same time each week keeps the pharmacokinetics predictable. If you do miss your scheduled day, the Patient Information Leaflet explains the permitted window, this is a clinical detail your prescriber or the leaflet should guide, not general advice.

The Wegovy SmPC on the eMC contains the authoritative storage and handling instructions, including the exact room-temperature duration once a pen has been used. Read it. It's written for patients as well as clinicians, and the storage section is clear.

If you'd like to understand how Wegovy compares to other semaglutide-based treatments, or what happens with the semaglutide injection licensed for diabetes, our clinical team has written plainly about the distinctions. And if you're ready to talk through whether Wegovy is the right fit for your situation, you can speak to our prescribers through a free consultation, reviewed the same day by a real clinician, not software.