Correct storage of your Mounjaro® pen ensures the medication remains safe, stable, and effective. Whether your pen is unopened or currently in use, following these temperature and timing guidelines is essential for your treatment success.
Use this guide to understand:
How to store unopened vs. in-use Mounjaro® pens.
Critical temperature thresholds (Refrigerated vs. Room Temperature).
What to do in common storage situations.
Storing unopened Mounjaro® pens
To ensure your medication remains stable until its printed expiry date, it should be kept within the "cold chain."
In the refrigerator: Store between 2°C and 8°C. Keep the pen in its original packaging and avoid storing it in the fridge door, where temperatures fluctuate most.
At room temperature: If necessary, an unopened pen can be kept outside the fridge at temperatures below 30°C for a maximum of 30 days.
The 30-day limit: Once an unopened pen has been out of the fridge for 30 days, it must be discarded, even if it has not yet reached its printed expiry date.
Storing a Mounjaro® pen currently in use
Once you have administered your first dose, the "in-use" period begins. Every Mounjaro® pen is designed to provide 4 weekly doses.
Storage options: You can continue to store your in-use pen in the fridge (2°C–8°C) or keep it at room temperature (below 30°C), depending on your preference.
Expiration of in-use pens: You must discard the pen 30 days after the first use, regardless of whether there is medication left in the reservoir.
Safety first: Always keep pens away from direct heat, sunlight, and out of the reach of children.
Common storage situations and safety checks
If you are unsure if your pen is still safe to use, follow these clinical safety rules:
Left out of the fridge overnight: The pen is generally safe to use as long as the room temperature stayed below 30°C. Return it to the fridge or continue to use it within the 30-day in-use window.
Frozen Mounjaro® pen: The pen is unsafe. You must discard it immediately. Never use medication that has been frozen, even after it has thawed.
Exposure to heat (Above 30°C): The pen is unsafe. If a pen has been stored in a car, near a radiator, or in direct sunlight above 30°C, it must be discarded even if it appears normal.
Past the expiry date: The pen is unsafe. Never use an expired Mounjaro® pen, regardless of how it was stored.
Key takeaway
Refrigerate unopened Mounjaro® pens at 2°C to 8°C to keep them stable until their expiry date. Once a pen is in use or leaves the fridge, it is only safe for 30 days, provided it stays below 30°C. If it has been frozen, overheated, or expired—discard it.