How Long Can You Store Mounjaro in the Fridge?

Mounjaro (tirzepatide) is a pre-filled injectable pen that is sensitive to temperature. According to the eMC product information for Mounjaro, unopened pens should be kept in a refrigerator at 2°C to 8°C and protected from light. They should not be frozen — a pen that has been frozen should not be used.

What about room temperature?

If you need to travel or your fridge is temporarily unavailable, Mounjaro pens can generally be stored at room temperature (below 30°C) for a limited period — check your leaflet or the electronic Medicines Compendium (eMC) for the specific number of days that applies, as this figure is product-specific and worth confirming directly. Once that window has passed, the pen should be discarded rather than returned to the fridge.

Does it have to stay in the fridge at all times?

No — refrigeration is the recommended long-term storage method, but short-term room-temperature storage is generally permitted within the limits stated in the product information. You do not need to panic if a pen has been out of the fridge briefly, but do check the leaflet to confirm how long is considered acceptable for your pen. For a deeper look at how to store your Mounjaro pen day to day, including what to avoid, there is more detail on that dedicated page.

Key storage rules to keep in mind

• Store unopened pens in the fridge at 2°C to 8°C until the expiry date.
• Do not freeze — discard any pen that has been frozen.
• Keep pens away from direct light and heat sources.
• Once removed from the fridge for room-temperature storage, do not put the pen back in the fridge to restart the clock.
• Check the expiry date on the pen before every injection.

If you are unsure whether a pen has been stored correctly, your prescriber or doctor — or a registered pharmacist — is the right person to ask before using it. For related reading, see whether keeping Mounjaro in the fridge is always necessary and whether Mounjaro has to stay in the fridge for more context on both sides of this question.

Keeping on top of storage is easier when you know exactly which pen you are using and when. GLP Trackr's dose logging feature lets you record each injection — including the date, time, and dose strength — so you always have a clear picture of where you are in your current pen and when you opened it. That record can be genuinely useful when you are trying to work out how long a pen has been out of the fridge, or simply to confirm your injection schedule is on track.

The app also includes dose reminders, so your weekly injection stays on your radar without you having to rely on memory alone. And if you ever have a question about storage or your pen to raise at your next appointment, the dose log gives you an accurate timeline to share with your prescriber.

For a broader understanding of how tirzepatide works and what to expect on your journey, the guide to how Mounjaro works is a good place to start.

A note on safety: if you are ever uncertain whether a pen has been stored correctly — whether it was left out too long, exposed to heat, or possibly frozen — do not use it without checking with your prescriber, doctor, or pharmacist first. GLP Trackr helps you record your journey, but any questions about whether a specific pen is safe to use belong with a healthcare professional.

Ready to keep your Mounjaro journey organised in one place? Download GLP Trackr free on the App Store or Google Play and explore it with a 7-day free trial.