Unopened Wegovy pens must be stored in a fridge between 2°C and 8°C until the expiry date printed on the pen. Once you've used a pen for the first time, it can be kept either in the fridge or at room temperature below 30°C for up to 6 weeks — a notably longer in-use window than Mounjaro's 30 days, reflecting differences between the two medicines' formulations. After 6 weeks, the pen must be discarded even if medicine remains inside. Wegovy must never be frozen; if a pen has been frozen, it should not be used, and you should contact your pharmacist for a replacement.
Unopened Wegovy pens should be kept refrigerated at 2°C to 8°C, ideally in their original carton to protect them from light. Stored this way, an unopened pen remains usable until the expiry date printed on the label and carton. Avoid storing pens in the fridge door, where temperature fluctuates more than in the main body of the fridge, and never freeze them.
After First Use: The 6-Week RuleOnce you've injected from a Wegovy pen for the first time, its shelf life changes. From that point, you have up to 6 weeks to use it — whether you keep it refrigerated, at room temperature, or move between the two — before it must be discarded, even if there's still medicine left inside.
| Before first use | After first use | |
|---|---|---|
| Storage | Refrigerate at 2–8°C only | Fridge (2–8°C) or room temperature, below 30°C |
| Maximum duration | Until printed expiry date | 6 weeks from first injection |
| Can you switch storage methods? | N/A | Yes — cycling between fridge and room temperature doesn't affect quality within the 6-week window |
| What resets the clock? | N/A | Nothing — the 6-week countdown starts at first use and cannot be paused or reset |
Worth knowing
Wegovy's 6-week in-use shelf life is notably longer than Mounjaro's 30-day window, which reflects genuine differences in how the two medicines are formulated, not a difference in how carefully they need to be handled. If you use both medicines at different points, or are switching between them, it's worth being clear on which rule applies to which pen — see our dedicated Mounjaro storage guide for that medicine's specific timeline.
It might seem like an unnecessary complication that different GLP-1 medicines have different in-use shelf lives, but this reflects genuine differences in each medicine's specific formulation and the stability data gathered during its development. Semaglutide (Wegovy's active ingredient) and tirzepatide (Mounjaro's active ingredient) are different molecules, and each manufacturer has tested and confirmed stability over different timeframes at room temperature. Rather than assuming one rule applies across all GLP-1 medicines, always check the specific guidance for whichever pen you're using.
It might seem overly cautious to discard a pen with medicine still inside, but the 6-week in-use limit reflects genuine stability data submitted as part of Wegovy's licensing. Once a pen has been used, its seal has been compromised in a way that unopened, refrigerated storage doesn't involve, and the medicine's stability at room temperature over time has only been tested and confirmed up to this specific window. Beyond 6 weeks, there isn't reliable data to confirm the medicine remains at full strength and free from degradation, which is why the limit is firm rather than a rough guideline.
What If Wegovy Has Been Left Out of the Fridge?If an unopened pen has been left at room temperature (below 30°C) for a short period, it can generally still be used, but shouldn't then be treated as having an unlimited fridge-stored shelf life going forward — if in doubt, contact your pharmacist for specific guidance rather than guessing. If a pen has been exposed to temperatures above 30°C, left in direct sunlight, or in a hot car, don't use it — contact your pharmacist, who can advise whether it's still safe or arrange a replacement.
Important
If Wegovy has been frozen at any point, do not use it under any circumstances, even if it appears to have thawed normally. Freezing damages the structure of semaglutide, and there's no way to visually confirm this has happened. Contact your pharmacist immediately for a replacement.
Regardless of how carefully you've stored your pen, it's worth checking it before every single injection, since damage or degradation isn't always something you'd anticipate from storage history alone.
- Look through the inspection window — the liquid should be clear and colourless to slightly yellow
- Never use a pen if the liquid looks cloudy, discoloured, or contains floating particles — this can also be a sign of a counterfeit product, so see our dedicated guide on how to spot fake weight loss injections if anything about your pen looks unfamiliar
- Check the expiry date printed on the carton — don't use a pen past this date
- Check the pen itself isn't visibly damaged or cracked
- Always use a new needle for each injection, if your pen requires a separate one
Because the 6-week countdown is unforgiving once a pen is opened, it's worth thinking about timing before you start a new pen, not just after. If you know you have an upcoming schedule disruption — travel, a change in routine, or a period where you might delay a dose — opening a new pen right before that disruption means you're more likely to lose unused medicine when the 6 weeks runs out. Where practical, starting a fresh pen at a point where your schedule is more predictable helps you get full value from each pen, particularly since Wegovy's longer in-use window gives you more flexibility to plan around than some other GLP-1 medicines.
Travelling With WegovyFor short trips within the UK, where temperatures are moderate, you can generally carry an in-use pen at room temperature (below 30°C) without special equipment, provided you stay within the 6-week window. For warmer climates or longer trips, a few precautions help ensure your medication remains safe and effective for the duration of your travel:
- Use an insulated travel pouch or cool bag designed for medication, especially in hot weather
- Avoid direct contact between the pen and ice packs, which can freeze it
- Keep pens in your hand luggage when flying, not checked baggage, both to avoid extreme temperature swings in the hold and to keep your medication with you
- Store pens in their original packaging where possible, and keep them out of direct sunlight and away from dusty or high-friction areas like the bottom of a rucksack
Once a pen reaches 6 weeks from first use, it must be discarded, even if medicine remains inside. Attempting to use leftover medicine beyond this point could mean an inaccurate or unreliable dose. Dispose of used pens in a proper sharps container; see our dedicated step-by-step injection guide for full disposal guidance.
Questions About Storing or Using Wegovy?
Our GPhC-registered pharmacy team is available to advise on storage, travel, or any concerns about your medication — not just at the point of prescription.
Start Your Free Online Consultation → Happy Pharmacy is a GPhC-registered pharmacy (No. 9012585) — Superintendent Pharmacist: Palvinder Deol — Rated 4.8★ Excellent on Trustpilot- Wegovy® (semaglutide) UK Summary of Product Characteristics, medicines.org.uk (emc).
- Novo Nordisk. Wegovy® Pen Storage and Handling Information, novomedlink.com.
- Eli Lilly and Company. Mounjaro storage comparison reference, medical.lilly.com/uk.
- electronic Medicines Compendium (emc). Wegovy FlexTouch — Instructions for Use and Patient Information Leaflet.