How to Store and Travel With Your Weight Loss Injection Pen Safely

Weight loss injection pens including Mounjaro and Wegovy are prescription medications that require specific storage conditions to remain safe and effective. Temperature, light exposure, and handling all matter. Get them wrong and you risk using a degraded dose that will not work as expected — or one that could cause harm.

How Should You Store Your Injection Pen at Home?

Both Mounjaro and Wegovy pens must be stored in a refrigerator at 2°C to 8°C before first use. Do not freeze them. Keep pens in their original carton, away from the freezer compartment and the back wall of the fridge where temperatures fluctuate. Do not store pens in the fridge door, as this area experiences the most temperature variation.

If you are unsure about correct storage, the Pharmacy Planet team is available to advise.

Once Started: Room Temperature Storage

After first use, both Mounjaro and Wegovy pens can be stored at room temperature (at or below 30°C) for a limited period. For Mounjaro, current guidance allows room temperature storage for up to 21 days after first use. For Wegovy, this period is 28 days. After these periods, any remaining medication must be discarded even if unused.

Keep room temperature pens away from direct sunlight and heat sources such as radiators, windowsills, and car dashboards.

Travelling Within the UK

For day trips and short journeys, a small insulated cool bag or medication travel wallet is sufficient. Avoid leaving your pen in a car on a warm day — car interiors can exceed 40°C in summer.

For overnight stays, most hotel rooms have a mini fridge or offer refrigeration on request. If you are also planning to dispose of used pens, Pharmacy Planet stocks sharps disposal bins and pre-injection swabs for safe and hygienic use on the go.

Travelling Abroad: What You Need to Know

Flying With Your Medication

Injectable prescription medications are permitted on flights, including in hand luggage. Always carry medication in hand luggage rather than checked baggage, as aircraft holds can reach freezing temperatures.

• Carry a copy of your prescription or a letter from your prescriber confirming the medication is for personal use
• Keep the pen in its original packaging with the pharmacy label visible
• Carry an insulated cool bag with an ice pack, ensuring the ice pack does not directly contact the pen
• Notify security staff you are carrying injectable medication

For guidance on injecting correctly when travelling, read our blog on how to inject your Wegovy dose.

Time Zone Differences and Injection Days

Both Mounjaro and Wegovy are weekly injections. You can adjust your dose day by one to two days without significantly affecting treatment — do not administer two doses within the same seven-day period.

Storing Medication at Your Destination

Most hotels will refrigerate medication on request. In very hot climates where ambient temperature regularly exceeds 30°C, keeping your opened pen refrigerated throughout the trip is the safest approach.

Disposing of Used Pens and Needles Safely

Used pens and needles are classified as clinical waste and must not go into household recycling or general waste. Pharmacy Planet stocks sharps bins for safe disposal. You can also read our blog on the environmental impact of injectable medications and how to safely dispose of your pen.

What to Do If Your Pen Has Been Exposed to Incorrect Temperatures

If your pen has been left in a hot car, frozen, or stored incorrectly for an extended period, do not use it. Contact Pharmacy Planet for guidance on replacement. Signs of a compromised pen include cloudiness, discolouration, or visible particles in what should be a clear solution.

Frequently Asked Questions

Can I take my Mounjaro pen on a plane?

Yes. Injectable medications are permitted in hand luggage. Carry your prescription documentation, keep the pen in its original packaging, and use an insulated bag to maintain temperature.

How long can Mounjaro be kept out of the fridge?

Once opened, Mounjaro can be stored at room temperature (at or below 30°C) for up to 21 days. Unopened pens should always be refrigerated at 2–8°C.

What happens if my pen is accidentally frozen?

Do not use a frozen pen, even if it appears to have thawed normally. Freezing can degrade the medication. Contact Pharmacy Planet for advice on replacement.

Can I change my injection day when travelling?

Yes, with some flexibility. You can adjust your day by one to two days without significantly affecting your treatment. Do not administer two doses within the same seven-day period.

Reviewed for clinical accuracy. Content is for informational purposes only and does not constitute medical advice. All prescription medicines require a valid prescription following appropriate clinical assessment.