Mounjaro (tirzepatide) is a biological medication that must be stored correctly to remain safe and effective. Improper storage can degrade the active ingredient, potentially reducing efficacy or causing harm. Here's a comprehensive guide for UK patients.
Refrigerator Storage (Unopened Pens)
Unused Mounjaro KwikPens should be stored in the refrigerator at 2°C to 8°C. In practice, this means:
- Keep pens in the main body of the fridge, not in the door (where temperatures fluctuate)
- Don't place pens directly against the back wall, where they may freeze
- Store them in their original box to protect from light
Under these conditions, pens remain usable until the expiry date printed on the packaging.
Room Temperature Storage
If needed, you can store unopened Mounjaro pens at room temperature (up to 30°C) for a maximum of 21 days. After 21 days at room temperature, any unused pens must be discarded — even if they haven't expired. Note the date you removed them from the fridge.
What to Avoid
- Never freeze Mounjaro — if a pen has been frozen, discard it immediately, even if it has thawed. Freezing damages the protein structure of tirzepatide
- Never expose to direct sunlight or leave in a hot car
- Never microwave or heat the pen to warm it up
- Don't store next to the freezer compartment in combined fridge-freezers
Travelling With Mounjaro
If you're travelling within the UK or abroad, take these precautions:
- Use a medical cool bag with ice packs for journeys longer than a couple of hours. Ensure the pen doesn't come into direct contact with ice
- For air travel, carry Mounjaro in your hand luggage — the cargo hold can reach freezing temperatures. You may want a letter from your prescriber confirming it's a prescription medication
- If staying in a hotel, use the minibar fridge (check it's between 2°C and 8°C and not set too cold)
- Consider purchasing a purpose-built insulin travel case — these maintain temperatures within the required range for several hours
How to Tell If Mounjaro Has Been Compromised
Before each injection, inspect the pen through the clear window. Discard the pen if:
- The liquid appears cloudy, discoloured, or has particles floating in it
- The pen has been frozen at any point
- It has been out of the fridge for more than 21 days
- The expiry date has passed
- The pen appears damaged or has been dropped from a significant height
UK Pharmacy Tip
When ordering Mounjaro online from a UK pharmacy, check their delivery method. Reputable pharmacies use temperature-controlled packaging for next-day delivery. If your order arrives warm or without cold packs in summer, contact the pharmacy immediately. Use MedsLens to find pharmacies that offer reliable cold-chain delivery.