Storage matters. GLP-1 medicines are biological injectables and are sensitive to temperature. Get the basics right and you protect both the dose and your money.
Standard storage
Refrigerate at 2 to 8°C, do not freeze, and keep pens in the original carton to protect from light. The exact in-use period and temperature limit differ between Mounjaro and Wegovy, and are specified in the patient information leaflet supplied with your pen — always check yours.
Out of the fridge
Both products allow a limited period stored below a stated temperature, after which the pen must be discarded. Once out of the fridge, the clock starts and does not reset if you put the pen back.
| Mounjaro | Wegovy | |
|---|---|---|
| Fridge storage | 2–8°C, protected from light | 2–8°C, protected from light |
| Maximum time out of the fridge | See the patient information leaflet supplied with your pen | See the patient information leaflet supplied with your pen |
| Maximum temperature when out of the fridge | See the patient information leaflet supplied with your pen | See the patient information leaflet supplied with your pen |
| Once the out-of-fridge limit is reached | Discard the pen | Discard the pen |
If it's been frozen
Discard it. Do not use, even if it thawed and looks normal. Freezing damages the peptide and you cannot rely on the dose to work.
If it's been left out too long
Don't guess. Contact your pharmacist with how long the pen was out and at what temperature. They can advise whether it's still safe to use or should be replaced.
Travelling with your pens
- Carry in hand luggage, never hold luggage — hold temperatures can freeze it.
- Use a cool bag with a gel pack, rather than direct ice contact.
- Carry your pharmacy label or prescription, and a supporting letter if flying.
- Check the medicines rules for your destination country before you travel.
- Plan for refrigeration at the other end — a mini-fridge or hotel fridge that's actually cold.
- Take a sharps bin, or arrange disposal at your destination.
Sharps disposal
Never household waste. Use a sharps bin and return it as directed. If you're not sure how sharps are collected in your area, ask your pharmacist.
The patient information leaflet supplied with your pen is the definitive source for storage limits. If a figure online disagrees with your leaflet, follow the leaflet.
When to see your pharmacist or doctor
- Never use a pen that has been frozen, is discoloured, or contains particles.
- If you are unsure whether a pen is still usable after being left out or after a fridge failure, contact your pharmacist before injecting rather than risking an ineffective dose.
- Report any suspected temperature excursion — it protects the next dose as well as this one.
Frequently asked questions
How long can it stay out of the fridge? There's a defined limit that differs by product — check your PIL.
Can I freeze it? No — discard if frozen.
What if my fridge failed? Contact your pharmacist with the details.
Can I fly with it? Yes, in hand luggage with documentation.
Does it need a cool bag? For any journey of length, yes.
See also how to inject Mounjaro and the Mounjaro dosage chart.
References
- Mounjaro Summary of Product Characteristics, electronic medicines compendium.
- Wegovy Summary of Product Characteristics, electronic medicines compendium.
- Civil Aviation Authority guidance on carrying medicines in hand luggage.
Reviewed by Jimah Alsaai MPharm, GPhC 2232652, Superintendent Pharmacist, Solira.