Do You Have to Store Mounjaro in the Fridge? (October 2026)

01 · The short answer

Do you have to keep Mounjaro in the fridge?

Yes: the UK guidance is to keep Mounjaro pens in a fridge at 2–8°C, and never to freeze them.¹¹³ That applies to every strength, from 2.5mg to 15mg, because all six use the same KwikPen design and the same active ingredient, tirzepatide.¹

The fridge is not a strict requirement at every moment, though. Once you have started using a pen, it can be kept out of the fridge not above 30°C for up to 30 days. After that, it should be discarded, even if some medicine remains.¹

The pen cap should stay on between uses to protect the medicine from light.¹³ If you ever want the full detail on how long a pen lasts in the fridge, see our guide on how long Mounjaro keeps in the fridge.

02 · Quick reference

Mounjaro storage rules in one table

03 · What to do next

What this means for you day to day

For most people the routine is simple: unopened pens go in the fridge, the pen you are using can be kept out of the fridge not above 30°C for up to 30 days, and you keep a note of the date you started it. If you are not yet a patient and want to see how treatment works, our Mounjaro pen page shows current doses and the free consultation, with every pen delivered in temperature-controlled packaging.

If you are still weighing up whether Mounjaro is right for you, our weight loss clinic explains how treatment fits around diet and activity.

Related guides: Do you need to store mounjaro in the fridge and Do you have to put mounjaro in the fridge.

04 · In-use pen rules

How long can an in-use Mounjaro pen stay out of the fridge?

An in-use pen can stay out of the fridge for up to 30 days, as long as it stays not above 30°C.¹ After that it should be discarded, even if the pen still contains medicine.

Figures quoted online often come from other countries' labels, so rely on the UK leaflet.

In practice, this means you do not need to keep returning the pen to the fridge after each injection. Many people keep the pen they are using in the fridge anyway, because it removes the need to track the days. Both approaches are fine within the limits.

If you do keep the pen out of the fridge, write the date you first took it out somewhere you will see it. A note on the carton or a reminder in your phone works well. The GLPTrackr companion app, which is free on iOS and Android, can also help you keep track of your treatment.

Keep the cap on to protect the pen from light, and keep it somewhere that stays comfortably not above 30°C. A warm car, a windowsill in direct sun, or a bag left next to a radiator is not a safe place.

05 · Unopened pens

Unopened pens: fridge until you start

Unopened pens should be kept in the fridge at 2–8°C and they keep until the expiry date printed on the box.¹ Leave the pen in its carton, which also helps protect it from light.

If you receive several pens, only the one you are about to use needs to come out. Your next pens wait in the fridge until their turn.

What if an unopened pen has been out of the fridge? Do not guess. Check with the pharmacy before using it rather than relying on a remembered day limit. Figures circulating online often come from other countries' labels, and they may not match the UK licence.¹

06 · Fridge placement

Where to put Mounjaro in the fridge

Put the pen in the main body of the fridge, in its carton, where the temperature stays steady and cold but never freezes. The target is 2–8°C.¹

The risk to avoid is freezing. A pen pushed against the back wall, next to a freezer compartment or a cooling element, can freeze without you noticing. A pen that has been frozen must not be used.¹ If you are unsure about your fridge, a simple fridge thermometer is a small accessory purchase that tells you whether it is staying in range.

Keep pens separate from food that could leak or contaminate, and out of the reach of children. Keep the cap on and the pen in its carton so it is protected from light.

A few practical habits help:

• Keep the carton and the leaflet together so the batch number and expiry date are easy to find.
• Do not store pens in a cool box with ice packs touching them directly, because that can cause freezing.
• If you share a fridge, tell the people you live with what the pens are and that they should not be moved to the freezer.

07 · Warm or frozen pens

What if Mounjaro gets warm or frozen?

If a pen has frozen, do not use it, even if it has thawed and looks normal.¹ Contact the pharmacy for advice and a replacement.

If a pen in use has been warm, the question is how warm and for how long. The licence allows an in-use pen to be kept not above 30°C for up to 30 days. If it has been in conditions above that, for example left in a hot car, the pen is outside the tested window and its potency can no longer be assured. Do not inject from it. Speak to the pharmacy first.

If an unopened pen has been left out, check with the pharmacy before using it. Please do not rely on a figure from a forum or a social media post.

Before every injection, look at the liquid. It should be clear and colourless. Do not use a pen that looks cloudy or discoloured, or has particles in it, or is past its expiry date.¹¹³

It is better to lose a pen than to inject a medicine you are unsure about. Pharmacies handle this question often, and a short call usually resolves it.

08 · Travelling with pens

Travelling with Mounjaro

You can fly with Mounjaro, and most holidays need no special arrangements. Carry pens in hand luggage, because hold luggage can fall below freezing.¹

Ideally, pack them in a cool bag with the prescription label or a copy of your prescription. In-use pens tolerate up to 30 days not above 30°C, so a typical trip does not need a fridge at your destination. For hot climates, use an insulated pouch. Check the destination's rules for travelling with prescription injectables before you fly.

Some practical tips for travel days:

• Keep the pen in its carton inside the cool bag so it is protected from light.
• Do not let it sit against an ice pack, because freezing is a bigger risk than warmth on most trips.
• Never leave it in a parked car, on a beach or in direct sun.
• Take spare pen needles and a way to dispose of them safely. Needles, a sharps bin and injection guidance are included with every EverydayMeds order.

If you will be away longer than the in-use window allows, plan ahead. An unopened pen stays in the fridge at home or at your destination until it is needed, so you can bring the next pen only when the current one is nearly finished. Our guide on how to store GLP-1 medicines covers the wider picture.

09 · Is the pen genuine

Checking a pen is genuine and still good

A genuine UK Mounjaro pen comes from a registered pharmacy with a batch number and expiry date, arrives cold-chain packaged, and the solution inside is clear and colourless.⁷

Do not use a pen that has been frozen, looks cloudy or discoloured, has particles in it, is past its expiry, or has been out of the fridge for more than 30 days, or above 30°C in use. If supply or packaging ever seems wrong, check the pharmacy on the GPhC register and contact the pharmacy before injecting.¹²

This is also why storage matters beyond the pen itself. Anyone offering Mounjaro without a consultation or prescription, or sending it with no cold-chain packaging, is a warning sign. Our pens come through official LillyDirect supply direct from Eli Lilly's UK distribution, and every order is reviewed by a GPhC-registered prescriber. They are delivered next day in temperature-controlled, discreet packaging, free of charge.

When your delivery arrives, put unopened pens in the fridge promptly and check the carton details against the label.

10 · Why storage matters

Why storage matters, and what it does not change

Storage protects the medicine's quality, but it does not make Mounjaro work harder. Keeping a pen cold does not make it more effective. It simply keeps the tirzepatide in the condition it was tested in.

That is the point of the storage rules: to make sure the pen you inject is the pen that was tested. A pen that has been frozen or overheated is outside that tested window, so there is no reason to expect it to behave the same way.

11 · Common mistakes

Common Mounjaro storage mistakes

The most common mistakes are letting a pen freeze, forgetting when the in-use window started, and trusting day limits from the wrong country.

• Freezing. A pen pressed against the back of the fridge or next to the freezer compartment may freeze. Never use a pen that has been frozen.¹
• Losing track of days. The in-use window is up to 30 days, not above 30°C. Note the date you took the pen out, or keep it in the fridge.
• Hold luggage. Hold luggage can fall below freezing, so pens belong in your hand luggage.
• Leaving the cap off. The cap protects the pen from light.
• Using online numbers. A figure you saw in a forum may come from a US or other overseas label. Use the UK leaflet, or ask the pharmacy.
• Keeping a finished pen. After the in-use window, discard the pen even if some medicine looks left.

12 · Support from us

Storage questions as an EverydayMeds patient

If you are one of our patients, ask us before you inject if anything about a pen worries you. Our support team is available Monday to Friday, 9am to 5pm, by email at support@everydaymeds.co.uk, through the account portal chat or by phone on 0333 207 0413.

Ongoing monthly clinical reviews are included, so storage, side effects and dose changes can all be raised with the prescribing team. Repeat orders re-check suitability, and nothing ships automatically. Orders placed by 3pm are dispatched the same day, and all six doses are in stock.

If you are thinking of starting, the consultation is free and reviewed by a GPhC-registered prescriber. A pen on our Mounjaro page starts at a standard price of £169.99 per month for the 2.5mg pen, prices checked 10 October 2026.