Does Mounjaro Go in the Fridge? UK Storage Rules (October 2026)

01 · The short answer

Does Mounjaro have to go in the fridge?

Yes, store your pens in the fridge. The UK guidance is 2–8°C, and the pen must never be frozen.¹ That applies to every strength, from 2.5mg to 15mg.

The fridge is not an all-or-nothing rule once you have started a pen. An in-use pen can be kept out of the fridge not above 30°C for up to 30 days, which is useful for short trips and for people without constant fridge access. After that it should be discarded, even if some liquid seems to remain.¹

02 · What to do

What should you actually do with your pen?

Put unused pens in the fridge as soon as they arrive. Keep them in the carton with the cap on so light does not reach them.¹

For the pen you are currently using, you can return it to the fridge between doses or keep it somewhere cool not above 30°C. Either way, count the days from first use and discard the pen when the 30 days are up. A note on the carton or a reminder in the free GLPTrackr app helps you keep track.

If you are still choosing a provider, you can see current strengths and prices on the Mounjaro pen page. Our pens arrive in temperature-controlled packaging with free next-day tracked delivery, and all six doses are in stock.

03 · The in-use 30-day rule

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

An in-use Mounjaro pen can stay out of the fridge not above 30°C for up to 30 days, after which it should be discarded.¹ You may see other numbers online, but they often come from other countries' labels.¹³

This is why many people ask whether they can use the same pen for longer than a month. The answer is no: the 30 days (not above 30°C) is a limit on how long the pen can be kept in use, not a target. Once that time is up, the pen goes in the sharps bin, even if it still feels partly full.

Can a pen go back in the fridge once it has been out? An in-use pen can be kept either way within the 30 days (not above 30°C), so returning it to the fridge between doses is fine. The 30 days is counted from first use, not from the time the pen was last chilled.

04 · Unopened pens out of the fridge

What if an unopened pen was left out?

Unopened pens should be kept in the fridge and keep until the expiry date printed on the box.¹ If an unopened pen has been out of the fridge, check with the pharmacy before using it rather than relying on a remembered day limit.¹³

Figures circulating online often belong to other countries' labels. Contact the pharmacy that supplied the pen, tell them how long and where it was left, and follow their advice. Our team can be reached Monday to Friday, 9am to 5pm, at 0333 207 0413 or support@everydaymeds.co.uk.

The same applies if a delivery arrives warm or late. Do not guess. Keep the pen in its carton, put it in the fridge, and ask before injecting.

05 · Freezing and heat

What happens if Mounjaro freezes or gets warm?

Never freeze Mounjaro, and never use a pen that has been frozen.¹ If you suspect it has frozen, discard it and speak to your pharmacy.

If a pen gets warm, the rule depends on the pen. An in-use pen that stays not above 30°C is within the licence for up to 30 days. Do not use a pen that has been above 30°C; contact the pharmacy for advice. For an unopened pen, check with the pharmacy before using it.

06 · Has my pen gone bad?

How can you tell if Mounjaro has gone bad?

A genuine UK Mounjaro pen has a batch number and expiry date, arrives cold-chain packaged, and contains a solution that is clear and colourless.¹ 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.

• Cloudy or coloured liquid: do not use.
• Visible particles: do not use.
• Frozen at any point: do not use.
• Past the printed expiry date: do not use.
• More than 30 days (not above 30°C) in use: discard.

If supply or packaging ever seems wrong, check the pharmacy on the GPhC register and contact it before injecting.¹² Report suspected side effects or faulty medicines through the Yellow Card scheme.⁷ Our own pharmacy is registered as GPhC 9012878 and supplies genuine KwikPens through official LillyDirect supply.

07 · Travelling with your pen

Can you travel with Mounjaro?

Yes, you can fly with Mounjaro. Carry pens in hand luggage, because hold luggage can fall below freezing, ideally in a cool bag with the prescription label or a copy of your prescription.¹

In-use pens tolerate up to 30 days not above 30°C, so most holidays need no special arrangements. For hot climates, use an insulated pouch. Unopened pens should stay in the fridge until you need them. Check the destination's rules for travelling with prescription injectables before you fly.

Do not use a pen that has been above 30°C or frozen. Keep the cap on to protect the pen from light.

08 · Pausing and restarting

What happens to tirzepatide after your last dose?

Tirzepatide has a half-life of about five days, so after a final dose it takes roughly four to five weeks to clear the system. There is no way to speed this up, and nothing needs doing while it clears.¹

Do not keep using a pen past its in-use limit just to avoid waste. Our guide to going back to a lower dose explains how that conversation works, and starting straight at 5mg covers why prescribers usually begin lower.

09 · Getting Mounjaro in the UK

How do you get Mounjaro in the UK?

Mounjaro is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber. NHS access is being phased in over several years, and NICE recommends it for adults with a BMI of at least 35 plus at least one weight-related condition.⁴ Many people who meet the licensed criteria choose regulated private treatment rather than waiting.

Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full. Our weight loss clinic explains the full process, including monthly reviews and dose titration. Your first 2.5mg pen costs £129.99 with code FIRST40 (standard price £169.99), and every later order is £25 off the standard price. Prices checked 10 October 2026.

If you are researching other prescribers for general questions, see whether a GP can prescribe Mounjaro. Our Mounjaro fridge guide and fridge requirement guide cover the same storage rules.