Quick Answer:
Mounjaro is the newest medications available in the UK for managing type 2 diabetes and obesity. This injectable treatment, when combined with a healthy diet and regular exercise, helps to lower blood sugar levels, promote weight loss, and minimise the risk of complications associated with diabetes or obesity.
If you’ve recently started using Mounjaro, your GP has likely explained its specific storage requirements. Similar to many injectable diabetes and weight-loss treatments, Mounjaro is a biologic drug, which makes it highly sensitive to heat and reliant on proper refrigeration and temperature control.
In this guide, we’ll explore the essential steps for handling and storing Mounjaro, so you can ensure its effectiveness and maximise the success of you treatment!
Related article: Does Insulin Need to Be Refrigerated?
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What is Mounjaro?
Mounjaro is a weekly injectable medication designed to support adults with type 2 diabetes or obesity issues. Its active ingredient, Tirzepatide, belongs to a class of drugs called GIP/GLP-1 receptor agonists.
This medication works by stimulating two key hormones that regulate blood sugar levels: glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). By boosting insulin production and reducing glucagon release, Mounjaro effectively helps lower blood sugar while reducing the risks of serious diabetes complications such as cardiovascular disease, kidney problems, vision loss, and nerve damage.
In December 2024, Mounjaro has also been approved for weight-loss in adults with obesity by the UK Medicines and Healthcare products Regulatory Agency (MHRA). Clinical studies indeed indicate an average reduction of 22.5% of body fat. This is because Tirzepatide slows digestion, enhances feelings of fullness, and increases energy expenditure, promoting weight reduction.
How to Store Mounjaro
To ensure Mounjaro maintains its effectiveness, proper storage is crucial. The active ingredient in your Mounjaro KwikPens, Tirzepatide, is particularly sensitive to changes in temperature and exposure to light, both of which can compromise its stability, efficacy, and safety for use.
Storage Guidelines
According to Eli Lilly, the manufacturer of Mounjaro in the UK:
- Store unopened pens in the refrigerator at a temperature between 2°C and 8°C.
- Mounjaro pens can be kept at room temperature (up to 30°C) for a maximum of 30 days if refrigeration is unavailable.
- Never freeze Mounjaro pens. Discard any pen that has been frozen, even if it appears fine after thawing.
- Keep pens in their original packaging to protect them from direct sunlight and light exposure.
How Long Can Mounjaro Be Out of the Fridge
The Mounjaro KwikPens sold in the UK can be kept unrefrigerated for up to 30 days, provided the temperature doesn’t exceed 30°C. It's different from Mounjaro pens sold in the USA, which can only stay out of the fridge for up to 21 days.
After this period, the medication will begin to deteriorate and should no longer be used. It’s important to note the date you remove a pen from the fridge and dispose of it if unused after 30 days.
Related article: Tips for Travelling with Mounjaro
What Happens If You Left Mounjaro Out of the Fridge?
Laboratory tests have shown that Mounjaro as sold in the UK is only stable for 30 days when unrefrigerated, after which it will start degrading. The medicine inside your pen gradually loses its potency when left out, eventually until it becomes completely inefficient.
Injecting Mounjaro that has been unrefrigerated for too long won't poison you, but it can seriously impact your weight-loss treatment, blood sugar levels, and ultimately your health.
That’s why you must always write down the date you've taken your Mounjaro pen out of the fridge and keep track of time. When in doubt, throw the pen away and get a new one from the fridge or pharmacy. Never use a Mounjaro pen that's been out of the fridge for too long. It simply isn't safe.
Does Mounjaro Expire?
Yes, like all medications, Mounjaro does expire. Mounjaro actually has two expiration dates:
- The one officially labelled on the pen by the manufacturer usually occurs about one year after purchase.
- The one that occurs 30 days after a pen has been removed from the fridge.
You must keep track of both expiration dates to ensure you never inject expired medicine.
Recognising Spoiled Mounjaro
Mounjaro is a clear, colourless-to-slightly-yellow liquid. If the liquid becomes cloudy, contains particles, or appears unusual, the pen should not be used. However, small air bubbles in the pen are normal and don’t affect its performance.
Keeping Mounjaro Cool When Away From Home
Maintaining the correct temperature for Mounjaro while on the move is essential. Here are some practical tips:
- Use a medical-grade cooler to safeguard pens in hot weather.
- Keep pens in shaded areas and avoid direct sunlight.
- Monitor storage conditions with a thermometer.
- Avoid leaving pens in vehicles or near heat sources.
- If travelling for extended periods, store unused pens in a refrigerator at your destination.
For more travel advice, check out our related article on Travelling with Mounjaro!
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