How Long Can Mounjaro Stay in the Fridge?

Mounjaro (tirzepatide) is a prescription-only, once-weekly injectable medicine supplied as pre-filled pens. According to the product information published on the electronic Medicines Compendium (eMC), unopened pens should be stored in a refrigerator at 2°C to 8°C, protected from light, and kept away from the freezer compartment — freezing damages the pen and means it must not be used.

The key practical points are:

• Unopened pens: safe to use until the expiry date on the label, provided they have been kept refrigerated throughout. Always verify the exact shelf-life against the leaflet that came with your specific batch.
• Opened or in-use pens: different rules apply — see the in-use storage guidance in your patient information leaflet, as the window is shorter once a pen has been used.
• Freezing: a pen that has been frozen should not be used, even if it appears normal after thawing.
• Temperature excursions: if a pen has been left out of the fridge, the rules change — find out more about how long Mounjaro can safely be out of the fridge and what to do if that happens.

If you are unsure whether Mounjaro has to stay in the fridge at all times or whether short room-temperature periods are acceptable, the eMC product information and your prescriber or pharmacist are the best sources of accurate, up-to-date guidance for your situation. For context on how Wegovy pens are stored, the rules are broadly similar — see our overview of how long Wegovy can stay in the fridge.

If you ever have a concern about a pen that may have been stored incorrectly, contact your prescriber, pharmacist, or healthcare professional before using it.

Knowing your storage window is one thing — remembering when each pen was opened, which dose you are on, and when your next injection is due is another matter entirely. That is where GLP Trackr's dose-logging feature earns its place.

Every time you inject, you can record the date, time, and dose strength directly in the app. That log gives you a clear, timestamped history — useful not only for keeping your weekly schedule on track, but also for spotting at a glance when a pen was first used, which matters for in-use storage timing. Paired with the app's dose reminders, it becomes much harder to lose track of where you are in your treatment.

If you want to understand more about how Mounjaro works and why consistent storage and dosing matter, the guide to how Mounjaro works gives useful background.

Always follow the storage and usage guidance provided by your prescriber or pharmacist — GLP Trackr helps you record your journey, but it is not a substitute for their advice. If you are ever uncertain about a pen's condition or storage history, check with your healthcare professional before injecting.

Ready to keep your weekly schedule and dose history in one clear place? Download GLP Trackr on the App Store or Google Play and explore it free for 7 days.