How Long Does Mounjaro Last in the Fridge?

Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are pre-filled injectable pens that need to be kept refrigerated before use. The general principle for both medicines is the same: store below 30 °C and protect from light, but the preferred place is a refrigerator (typically 2 °C to 8 °C). Always check the specific guidance in your own pen's patient information leaflet or on the electronic Medicines Compendium (eMC), as it takes precedence over any general summary.

Unopened pens

An unopened Mounjaro pen stored in the fridge can generally be kept until the expiry date on the label. The same principle applies to unopened Wegovy pens. Never use a pen past its expiry date, and inspect the solution before each injection — if it looks cloudy, discoloured, or contains visible particles, do not use it and speak to your prescriber or pharmacist.

After first use (opened pens)

Once a Mounjaro pen has been used for the first time, the storage window is shorter. Check the leaflet that came with your pen for the precise figure, but guidance typically states that an opened Mounjaro pen kept in the fridge should be used within a limited number of days — do not rely on memory alone; write the date of first use on the pen or log it somewhere reliable. The same caution applies to opened Wegovy pens; check your own product's leaflet for the exact timeframe.

Important storage points to keep in mind

• Do not freeze Mounjaro or Wegovy — a pen that has been frozen should not be used.
• Keep pens away from the freezer compartment at the back of the fridge.
• Pens can generally be kept at room temperature (below 30 °C) for a limited period if refrigeration is not available — check your leaflet for the exact number of days allowed.
• Always replace the cap after use and keep the pen out of direct light.
• If you are unsure whether a pen has been stored correctly, ask your prescriber, pharmacist, or the provider who supplied it before injecting.

For a broader look at how long one Mounjaro pen lasts across your injection schedule, including how dose strength affects usage, that page has more detail.

One of the most practical things you can do to protect your medication — and avoid wasting a pen — is to record the date of every injection. GLP Trackr's dose logging feature lets you log each shot with the date, time, and dose strength the moment you give it, so you always know exactly when a pen was first used and when your next dose is due.

If you ever miss a dose or are unsure whether a pen is still within its usable window, having a clear injection log makes it much easier to have an informed conversation with your prescriber or pharmacist — rather than relying on memory. The app's dose reminder feature also means you are less likely to leave a pen unused and forgotten at the back of the fridge for longer than intended.

Any decision about whether to use a pen you are unsure about — or what to do if a dose has been missed — belongs with your prescriber or pharmacist, not a tracking app. GLP Trackr gives you the record; your healthcare professional gives you the guidance. You can learn more about how Mounjaro works and what to expect from your treatment in our overview guide.

Keep your injection history clear and your storage habits consistent — log every dose in GLP Trackr as soon as you give it. Available free on the App Store and Google Play, with a 7-day trial to get started at no cost.