How Do You Store Mounjaro? What Every User Should Know

Mounjaro (tirzepatide) is a prescription-only, once-weekly injectable medicine supplied as a pre-filled pen. Because it is a biological medicine, temperature matters — exposure to excessive heat, freezing, or direct sunlight can affect its quality.

In the fridge (before use)

Unopened pens should be kept in a refrigerator at 2°C to 8°C. Store them in their original carton to shield them from light. Do not place pens near the freezer compartment or against the back wall of the fridge where temperatures can drop below freezing — a frozen pen should not be used. For more detail on how long a pen can remain in the fridge before use, see our page on storing Mounjaro in the fridge.

At room temperature (in use or travelling)

If you need to take a pen out of the fridge — for travel, for example — it can generally be kept at room temperature below 30°C for a limited period. The exact duration is stated in the patient information leaflet included with your pack, and on the electronic Medicines Compendium (eMC) product information at medicines.org.uk. Always refer to those sources rather than relying on a general figure, as guidance can be updated.

What to avoid

• Freezing: do not use a pen that has been frozen, even if it has thawed.
• Heat and sunlight: keep pens away from direct sunlight and heat sources such as radiators or car gloveboxes in warm weather.
• Shaking: do not shake the pen vigorously.

Always check the pen before use — the solution should be clear and colourless to slightly yellow. If it looks cloudy, discoloured, or contains visible particles, do not use it and contact your prescriber or pharmacist.

If you have questions about how Mounjaro works more broadly, the how Mounjaro works guide covers its mechanism in plain language. You may also find it useful to read about getting a Mounjaro prescription or what happens when coming off Mounjaro.

One practical challenge with weekly injectable medicines is simply keeping track of where you are — which pen you used, when, and what dose. GLP Trackr's dose logging feature lets you record each injection as you go, including the date and dose strength, so you always have a clear picture of your supply and schedule.

Paired with dose reminders, this means you are less likely to forget an injection day or lose track of how many pens you have remaining. If you do notice something unexpected — such as a pen that may have been left out longer than recommended — logging it and noting it as something to discuss with your prescriber keeps that information in one place rather than relying on memory at your next appointment.

GLP Trackr also lets you track side effects over time, which can be useful if a storage issue ever affected how a dose felt. Any concerns about a pen's condition or your own experience should always be raised with your prescriber or doctor — they are best placed to advise you based on your individual circumstances.

If you want a reliable log of every dose you take, available to review or share with your healthcare team, give GLP Trackr a try — it is available free on the App Store and Google Play, with a 7-day trial to get started.