Do You Need to Keep Mounjaro in the Fridge?

According to the product information for Mounjaro, unopened pens should be stored in a refrigerator at 2°C to 8°C. They should not be frozen — if a pen has been frozen, it should not be used. Keep pens away from direct light and out of reach of children.

What about room temperature?

If refrigeration is temporarily unavailable — for example, while travelling — Mounjaro pens can generally be kept at room temperature for a limited period. The exact number of days permitted at room temperature is stated in the patient information leaflet that came with your pen; always check that leaflet or the electronic Medicines Compendium (eMC) rather than relying on a general figure, as guidance can be updated. Once a pen has been stored outside the fridge, it should not be returned and re-refrigerated repeatedly.

Practical storage tips

• Store pens in their original carton to protect them from light.
• Choose a consistent spot in the fridge — a middle shelf away from the freezer compartment is usually best.
• Never leave a pen in a hot car or on a sunny windowsill, as heat can degrade the medicine.
• If you are unsure whether a pen has been exposed to unsuitable temperatures, contact your prescriber or pharmacist before using it.

If you are travelling and wondering how to manage your pens away from home, the same principles apply — check your patient information leaflet and plan ahead. Questions about keeping your Mounjaro pen correctly throughout your treatment are covered in more detail in our related guide, and you can also read about what happens if your pen has been left out for guidance on specific situations.

Knowing when you last used a pen — and how long the current one has been out of the fridge — is much easier when you have a simple log to refer back to. GLP Trackr's dose logging feature lets you record every injection with its date and time, so you always have an accurate record of your weekly schedule. That record can also help if you need to check how long a pen has been in use.

Alongside dose logging, the app's reminder feature means your weekly injection day is flagged in advance — useful both for planning your storage routine and for making sure a pen is ready at the right temperature before you need it. If you are also on Wegovy (semaglutide), the same storage principles broadly apply; you can find out more in our guide to keeping Wegovy in the fridge.

For a broader overview of managing your Mounjaro journey, the Mounjaro hub brings together guides on dosing, side effects, injection and more.

Any concerns about whether your pen has been stored correctly — or whether it is still safe to use — should be directed to your prescriber, pharmacist, or healthcare professional. GLP Trackr helps you keep an organised record to support those conversations, but it is not a substitute for professional advice.

Keep your injection schedule organised and your dose history in one clear place — download GLP Trackr on the App Store or Google Play and start a free 7-day trial today.