Does Mounjaro Need to Be Refrigerated?

Biological medicines like tirzepatide and semaglutide contain protein-based active substances that can degrade when exposed to high temperatures or light for extended periods. Refrigeration slows that degradation and preserves the medicine's potency from the time it leaves the manufacturer until the moment you inject.

Unopened pens

Unopened Mounjaro and Wegovy pens should be stored in a refrigerator — typically between 2°C and 8°C (36°F and 46°F). Check the patient information leaflet or the electronic Medicines Compendium (eMC) entry for your specific medicine, as this is the authoritative source for your exact pen's storage requirements. Keeping pens in the fridge door is generally fine, but avoid the freezer — a frozen pen should not be used.

After opening or at room temperature

Once you have started using a pen, or if you have taken it out of the fridge for travel or convenience, most pens can be kept at room temperature for a limited period. The exact number of days permitted varies by product and formulation, so rather than relying on a general figure, always confirm this in the leaflet that came with your pen. If you are unsure whether a pen has been stored correctly, contact your prescriber or pharmacist before using it.

Does it need to reach room temperature before injecting?

Many people find a cold injection from the fridge more uncomfortable. Taking your pen out of the fridge around 30 minutes before your injection is a common approach and is often mentioned in patient information materials — but check your own leaflet for specific guidance. Never try to warm the pen quickly using hot water or a microwave.

For more detail on how Mounjaro works and what to expect during your treatment, see our guide on how Mounjaro works. You may also find it helpful to read about how to store your Mounjaro pen safely and keeping Mounjaro in the fridge for practical day-to-day tips.

Staying on top of your weekly injection schedule — including knowing exactly which pen you are on and when your next dose is due — is one of the practical challenges of GLP-1 life. GLP Trackr's dose logging feature lets you record each injection as you go: the date, the dose strength, and which pen you used. That running log makes it easy to spot if a pen has been sitting out longer than expected, and gives you a clear record to bring to your prescriber if you have any concerns about storage.

Dose reminders also help — so even when life gets busy, your weekly schedule stays on track and pens are less likely to be left out of the fridge and forgotten. You can also use the storage checklist approach alongside the app to build a consistent routine around each injection day.

If you ever have any doubt about whether a pen has been stored correctly, or whether it is still safe to use, speak with your prescriber or pharmacist before injecting — they are the right people to advise you, and GLP Trackr's records can help you explain exactly what happened.

Log your doses, set your reminders, and keep your weekly injection routine on track — GLP Trackr is free to try for 7 days on the App Store and Google Play.