How to Store Mounjaro: Everything You Need to Know

According to the electronic Medicines Compendium (eMC), Mounjaro pens should be stored in a refrigerator at 2°C to 8°C before first use. 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 the reach of children.

Before first use

Unopened pens should remain in their original carton in the fridge. Storing them upright or lying flat is both acceptable, but protecting them from light is important. Check the expiry date on the carton before use.

After opening or first use

Once you have used a Mounjaro pen, storage options can change. The patient information leaflet that came with your pen — or the electronic Medicines Compendium (eMC) entry for Mounjaro — is the definitive source for how long an in-use pen may be kept and under what conditions. Always check your own leaflet rather than relying on remembered figures, as guidance can be updated.

Travelling with your pens

If you need to travel, keeping pens cool is important. A small insulated cool bag (without ice packs that could freeze the pen directly) is a practical option many people use. Do not leave pens in a hot car or in checked luggage where temperature control cannot be guaranteed. For longer trips, plan ahead with your prescriber or pharmacist about how to manage your supply safely.

What to do if storage goes wrong

If you suspect a pen has been frozen, left in excessive heat, or stored incorrectly for a period of time, do not assume it is still effective. Contact your prescriber, doctor, or a registered pharmacist for guidance before using it. It is worth noting this kind of incident so you can discuss it at your next appointment — see the section below on how GLP Trackr can help you keep a record.

For broader context on managing your Mounjaro journey, the Mounjaro guide on GLP Trackr covers many aspects of life on this medication. You may also find it useful to read about preparing for your first Mounjaro dose, which includes practical tips for getting started confidently.

Knowing where each pen is in its lifecycle — which one is current, when it was started, and when your next dose is due — becomes genuinely useful when you are managing a weekly injection schedule. GLP Trackr's dose logging feature lets you record each injection with its date, time, and dose strength, so you always have a clear picture of your supply and schedule.

Alongside dose logging, the app's dose reminders mean you are less likely to forget an injection day — and if you do need to note that something went wrong with a pen (a storage issue, a missed dose, an unexpected event), logging it in the app gives you something concrete to bring to your next prescriber appointment rather than trying to recall it from memory.

If you also take Wegovy or are curious about storage for semaglutide, the guidance on how to store your Wegovy pen follows similar principles and is worth reading alongside this page.

GLP Trackr is available free on the App Store and Google Play — start a 7-day free trial and use it to keep your injection schedule organised and your progress clearly logged.

Storage questions that relate to the safety or quality of your medication should always be directed to your prescriber, doctor, or pharmacist — they can advise based on the specifics of your situation. GLP Trackr is a tracking tool, not a substitute for that professional guidance.