Does Mounjaro need to be refrigerated? Here's how to store it correctly and avoid wastage

You’ve got a handle on how Mounjaro supports weight loss, you know when and how it needs to be injected, and you’re convinced it’s the right weight loss injection for you. But do you know how to store Mounjaro so it stays safe and effective?

This article explores exactly that. Here’s the lowdown on correct Mounjaro storage to ensure the medication works as well as possible.

Does Mounjaro need to be refrigerated?

For the most part, yes. 

If possible, you’re best storing unopened Mounjaro pens in the fridge between a temperature of 2ºC and 8ºC [1]. Keeping them in your home fridge is totally fine, as long as you can maintain a fairly even temperature. The fridge door, for instance, is often prone to temperature fluctuations. 

Putting Mounjaro at the back of the fridge can also be risky, as there’s a chance it may freeze – another no-no which we’ll dive into further down. And you might want to place it away from food, too, as it could accidentally spill all over your medication. To avoid any of these mishaps, some patients purchase a dedicated mini fridge for their medication.

If necessary, unused pens can be stored outside the fridge for up to 21 days – as long as the temperature doesn’t exceed 30ºC. This means you can briefly take it out of the fridge if you need to transport it somewhere.

This recommendation is something to take note of during the summer months. While scorching hot summer days aren’t super common here in the UK, putting Mounjaro in the fridge will keep your medication at an optimal temperature without the risk of it spoiling.

Manufacturer guidelines for storage

Eli Lilly, the manufacturer that makes Mounjaro, recommends the fridge as the best storage spot [1]. The company also advises:

• Keeping the medication in its box to protect it from light
• Storing it only until its expiration date (you’ll find this on both the pen label and the box)
• Making sure it’s out of sight and reach of children and pets

Should Mounjaro injections be cold or room temperature before use?

They can be either. Your Mounjaro pens are perfectly fine and safe to use straight from the fridge, but if the cold needle is too uncomfortable, you can leave them out for a little while to come to room temperature before using. 

Why proper storage matters

Many medications come with specific storage instructions to maintain their efficacy, and Mounjaro is no different. Keeping it in the fridge ensures it stays stable and working as it should.

If Mounjaro is kept outside the fridge for too long or in temperatures that are too hot, it can break down. It can then become ineffective, and the strength of the dosage can become compromised – not exactly ideal when you’re trying to stick to a specific dosing schedule. 

Storing it away from children and pets is also a must because it keeps them safe. Both the needle and the medication itself pose a danger.

Storing Mounjaro at home

Once your pens arrive, how should you store them?

How long does Mounjaro last in the fridge?

As long as they’re stored in a fridge temperature of between 2ºC and 8ºC, you can use your Mounjaro pens up until the expiry date printed on the pen label and box.

Unopened Mounjaro pens have a shelf life of 24 months, while opened ones will only last 30 days from the day you open them.

Can I freeze Mounjaro?

Mounjaro should never be frozen or stored in your freezer. If your pen becomes frozen, you’ll unfortunately have to throw it away as it’s no longer usable.

Freezing can make the medication either ineffective or possibly even unsafe to use, as it can compromise the medication and the pen itself. Thawing it won’t make a difference, either – it’s the freezing process that can cause damage.

What happens if Mounjaro is left out of the fridge?

If your Mounjaro pens have been left out of the fridge for whatever reason, they should still be fine to use as long as you’re within the 21-day window and the medications haven’t been left in temperatures exceeding 30ºC.

If you’re not ready to use them just yet, pop them back in the fridge as soon as you can to get them back to an optimal temperature.

If it has been longer than 21 days since the medication was in the fridge or the temperature exceeded 30ºC, your best bet is to throw it away.

Storing Mounjaro after opening

Each Mounjaro pen typically provides four weekly doses – so how should you store your medication once you’ve started injecting it?

How to store Mounjaro pens after first use

After you’ve opened your Mounjaro pen, it can be at room temperature for up to 30 days, as long as the temperature stays below 30ºC. You should also keep it away from heat and light to ensure the medication stays effective. Storing it in its original box can help with this [2].

Just make sure to remove the needle to prevent leakage and the medication from spoiling, and leave the pen cap on.

Shelf life of opened pens

Opened Mounjaro pens have a shelf life of 30 days after the first use. Once you’ve administered four weekly doses or it’s been 30 days since you first used the pen, you should throw it away.

Travelling with Mounjaro

If you plan on travelling with Mounjaro, continuous refrigeration might not be possible. There are a few things you can do to try and keep your medication at a relatively stable temperature, though.

How to store Mounjaro when travelling

• Use an insulated or cooler bag and ice packs to keep the medication cool (although avoid placing the medication directly on the ice packs)
• If you're travelling by plane, pack your pens in your hand luggage, as this is less prone to temperature fluctuations than hold luggage. And always check your airline's restrictions for carrying prescribed medication
• Keep your pens in the original box to protect them from light
• Place your pens back in the fridge as soon as you’re able
• Remember that they can be at room temperature for up to 21 days, as long as the temperature stays below 30ºC

If something goes wrong

Even with the best planning, accidents can and do happen. Here’s how to handle any storage mishaps.

What to do if Mounjaro hasn’t been stored properly

If your pens have been in extreme temperatures, stored at room temperature for too long or frozen, you’ll have to throw them away. There’s a risk they won’t be safe to use, so you’re best erring on the side of caution and discarding them.

How to tell if it’s still safe to use

There are sometimes a few tell-tale (and visible) signs that Mounjaro is safe or unsafe to use. If the pen is clear, colourless to very pale yellow, there are no floating particles, and it’s cool to the touch, it should be safe to use – as long as it hasn’t been exposed to the conditions mentioned above.

On the other hand, if you notice that it’s cloudy, has visible particles or is warm or hot to the touch, once again you should discard it and use a new pen.

Safely disposing of Mounjaro

Discarding used Mounjaro pens isn’t quite as simple as throwing them in your household bin. Learn how to dispose of them safely.

How to dispose of expired or compromised pens

You should put any used, compromised or expired Mounjaro pens in a dedicated sharps bin – this protects you and others when handling them [3].

You can usually get a sharps disposal container from your GP or local pharmacy with a description. Alternatively, you can use a heavy-duty plastic container with a tight-fitting lid and labelling to indicate that there’s hazardous waste inside.

Needle safety and local disposal options

Sharps bins also can’t go in your usual rubbish. Some UK councils provide a clinical waste collection service for sharps bins, but you may also be able to drop them off at your local pharmacy, GP or a registered drop-off location in your council area. You can find out if your council area provides a collection service here.

Access Mounjaro (and lose more weight) with Juniper

Looking to lose weight using Mounjaro? You might want to consider Juniper.

With the Juniper Programme, you can access weight loss medication tailored to your health and goals — never one-size-fits-all. Our app helps you track progress, connect with your care team, adjust medication as needed, and access expert support. You'll also get structured tools to build lasting habits and ongoing care.

Kickstart your weight loss journey with Wegovy or Mounjaro, two groundbreaking weight loss medications that mimic the GLP-1 and GIP hormones, respectively, to help control cravings, delay stomach emptying, and keep you feeling fuller for longer. These clinically backed treatments help members experience up to 20% body weight loss.

We help you make lifestyle and habit changes, and we’re in it with you for the long run, having helped thousands of women achieve their weight loss goals.

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