Does Mounjaro Have to Be Refrigerated?

Mounjaro and Wegovy are protein-based medicines. Like many biological treatments, their active substances — tirzepatide and semaglutide respectively — can degrade if exposed to excessive heat, freezing temperatures, or direct light. Proper storage helps ensure the medicine remains effective for the duration of its shelf life.

General storage guidance (always check your leaflet)

The patient information leaflet (PIL) included with your pen, or the Summary of Product Characteristics (SmPC) on the electronic Medicines Compendium, contains the precise storage instructions for your product. As a general principle, pre-filled pens for both Mounjaro and Wegovy are typically stored in the refrigerator at around 2°C to 8°C. Most manufacturers also allow the pen to be kept at room temperature for a limited period once removed from the fridge — check the leaflet that came with your pen for exactly how long this applies, as figures vary by product and should not be assumed.

What to avoid

• Freezing: do not freeze the pen or store it next to the freezer compartment — frozen medicine should not be used.
• Heat and sunlight: keep pens away from direct sunlight and heat sources such as radiators or car dashboards.
• Out-of-fridge time: if your pen has been left out longer than the leaflet permits, contact your prescriber or pharmacist before using it.

Does it have to be taken at the same time each week?

Both Mounjaro and Wegovy are once-weekly injections. While consistency in your weekly schedule can make it easier to remember your dose, your prescriber or the product leaflet is the right source for any specific guidance on timing flexibility — this is not something to adjust without checking first. For more detail on how Mounjaro works and what to expect from your treatment, see our guide on how Mounjaro works.

For further reading on keeping your pen in the best condition, you may also find it helpful to explore related guidance on whether Mounjaro needs to be refrigerated and keeping your Mounjaro pen in the fridge. Official SmPC information is available on the electronic Medicines Compendium (eMC) for both products.

One practical consequence of weekly injection medicines is that it is easy to lose track of when you last injected — and whether the pen you have out of the fridge is within its permitted out-of-fridge window. GLP Trackr's dose logging feature lets you record each injection with the date, time, and dose strength the moment you do it, so you always have an accurate record to refer back to.

Beyond dose logging, the app's reminder feature means you will get a gentle nudge when your next weekly injection is due — useful for maintaining a consistent schedule. And if you ever notice something feels off and want to record it, the side-effect tracker lets you log how you feel after each injection so you can spot any patterns and bring a clear picture to your next prescriber appointment.

GLP Trackr also generates a doctor report from your logged data, making those conversations with your prescriber more informed and efficient. You can also read more about storing your Mounjaro pen safely in our related guidance.

A note on safety: if you are ever unsure whether a pen has been stored correctly — or if it looks, smells, or feels different to usual — do not use it. Contact your prescriber, doctor, or pharmacist promptly. GLP Trackr is a tracking tool and is not a substitute for advice from your healthcare professional.

Keep your weekly routine on track and your injection history in one place — download GLP Trackr on the App Store or Google Play and start your free 7-day trial today.