Mounjaro Shelf Life: What You Need to Know About Storage and Expiry

Mounjaro (tirzepatide) is a once-weekly injectable medicine supplied in pre-filled pens. Like many injectable medicines, it requires careful storage to remain effective.

Refrigerated storage

Unopened Mounjaro pens should be stored in a refrigerator. Check the leaflet that came with your pen, but according to the electronic Medicines Compendium (eMC), pens should generally be kept at 2°C to 8°C and used before the expiry date printed on the label. Do not freeze them — a frozen pen should not be used.

Once removed from the fridge

Once a pen has been taken out of refrigerated storage, it can typically be kept at room temperature (below around 30°C) for a limited period — check your pen's patient information leaflet for the exact timeframe, as this is the definitive source for your specific product. This is especially relevant to understand if you are travelling or if your pen has accidentally been left out. For more detail on what happens to the pen once it has been used or removed from cold storage, see our guide on Mounjaro shelf life after opening.

Shelf life in the fridge

While refrigerated and unopened, a Mounjaro pen is generally usable until its printed expiry date. Always check this date before each injection — your pen's leaflet and the eMC product information are the most reliable sources for your exact pen.

Signs a pen may no longer be suitable

Before injecting, inspect the solution. It should be clear and colourless to slightly yellow. If it looks cloudy, discoloured, or contains particles, do not use it and contact your prescriber or pharmacist. Similarly, never use a pen past its expiry date.

For broader information about Mounjaro and how it works, visit our Mounjaro overview. If you are also interested in how Wegovy compares in terms of storage and pharmacokinetics, our page on Wegovy half-life and duration covers the semaglutide side of things.

It is also worth being aware of general safety considerations when handling your pen — our page on risks and safety considerations for Mounjaro covers this in more detail.

One of the most practical ways to stay on top of shelf life is simply knowing exactly when you last injected and which pen you are currently using — and that is where logging each dose in GLP Trackr pays off immediately.

The app's dose and injection logging lets you record each shot with its date, time, and dose strength. Over time this builds a clear picture of your injection schedule, so you can cross-reference when a pen was first taken out of the fridge and whether it needs to be used soon. If you have ever reached for a pen and been unsure whether it has been sitting at room temperature for too long, having a log takes the guesswork out of it.

Alongside dose logging, dose reminders help make sure your weekly schedule stays consistent — missed or delayed doses can sometimes mean a pen gets forgotten and left out longer than intended.

Any concerns about a pen's condition, whether it has been stored outside the fridge for longer than expected, or questions about whether a dose is still suitable, should always go to your prescriber, doctor, or pharmacist — they can give guidance specific to your situation. GLP Trackr helps you record the details so those conversations are easier and better informed.

Keep every injection logged and your schedule easy to follow — download GLP Trackr on the App Store or Google Play and start a free 7-day trial today.