GLP-1 Storage: Fridge, Temperature and Travel Rules (October 2026)

01 · The short answer

How should you store a GLP-1 pen?

Keep unused pens in a fridge at 2–8°C and never freeze them. Keep the pen cap on to protect it from light, and never use a pen that has been frozen.¹

Unopened pens stay in the fridge and keep until the expiry date printed on the box.¹³ Our Mounjaro pen storage guide and Mounjaro storage temperature page go into the detail.

02 · Out of the fridge

What happens if a GLP-1 pen is not refrigerated?

It depends on whether the pen is already in use. An in-use Mounjaro pen can be kept out of the fridge not above 30°C for up to 30 days, after which it should be discarded.¹

For an unopened pen that has been left out, do not rely on a remembered day limit. Check with the pharmacy before using it, because figures circulating online often come from other countries' labels.¹³

Ready to start treatment? Our Mounjaro pen comes after a free online consultation, and our weight loss clinic explains how it works. Pens arrive in temperature-controlled packaging.

03 · Temperature and containers

Storage temperature and containers

The fridge is the right place for spare pens: 2–8°C, and never frozen.¹ The pen is designed to be kept in its own packaging with the cap on, which also protects it from light.

A separate storage case is optional. If you use one, treat it as a convenience for carrying the pen, not a substitute for the fridge.

The Wegovy fridge storage guide covers that product separately, as its rules come from its own leaflet.

04 · Travelling with pens

Travelling with GLP-1 pens

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.

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. Check destination rules for travelling with prescription injectables before you fly.

05 · Is my pen still good?

How can you tell if a pen has gone bad?

Look at the solution first. 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.

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

Report any suspected problem through the Yellow Card scheme.⁷

06 · Why storage matters

More about GLP-1 medicines

To understand what the medicine does once injected, see GLP-1 physiology; for how other injectables differ, see whether pramlintide is a GLP-1.