How long does a pen last?
Usually 4 weeks. A Mounjaro KwikPen, a Wegovy FlexTouch and a Zepbound KwikPen each hold 4 doses, and US single-dose Zepbound pens come 4 to a box, so your fifth weekly jab needs a new pen. Wegovy 7.2mg is the exception: three 2.4mg injections a dose. How long a started pen keeps differs by brand.
Work out your dates
Pick your pen and its first dose day for the four dose days, when the next is due and the label’s limit. It counts dates; it doesn’t change your prescriber’s advice.
How long a pen keeps
Each label’s own limit, quoted as written.
| Pen | In the box | The label’s limit |
|---|---|---|
| Mounjaro KwikPen | One pen, four doses | can be stored unrefrigerated not above 30 ºC for up to 30 days after first use and then the pen must be discardedMounjaro KwikPen patient leaflet |
| Wegovy FlexTouch | One pen, four doses; at 7.2mg, three make one dose | You can keep the pen for 6 weeks when stored at a temperature below 30°C or in a refrigerator (2°C to 8°C)Wegovy FlexTouch patient leaflet |
| Zepbound KwikPen | One pen, four doses | after a total of 30 days at room temperature, 30 days after first use, or after taking 4 weekly dosesZepbound prescribing information |
| Zepbound single-dose pens | Four pens, one dose each | can be stored unrefrigerated at temperatures not to exceed 30°C (86°F) for up to a total of 21 daysZepbound prescribing information |
Before the first dose, and after the last
Before you start
Fridge, 2 to 8°C, say Mounjaro, Wegovy and Ozempic; Zepbound’s label also allows limited room temperature.
If it froze
The Mounjaro, Wegovy and Ozempic leaflets are all clear that a pen that has been frozen must not be used.
After dose 4
There may be a little medicine left in your pen after dose 4. Mounjaro’s leaflet says not to try to use it.
Questions
How many doses are in a Mounjaro pen?
Four. The UK leaflet says each KwikPen contains 4 doses, in whichever strength you’re prescribed. Taken once a week, that’s 4 weeks.
How long does a Wegovy pen last once it’s open?
The Wegovy FlexTouch leaflet says you can keep the pen for 6 weeks when stored below 30°C, or in the fridge. It holds four doses, so on a weekly schedule you’ll finish it well inside that.
Does a Wegovy pen last 4 weeks at 7.2mg?
No. The leaflet gives the 7.2mg dose as three 2.4mg injections on the same day, says you may need to use multiple pens, and asks you to make sure you have enough to complete the dose before you start. Your pharmacist can help you plan supply.
Is there medicine left after the last dose?
There can be. Mounjaro’s leaflet says not to try to use any remaining medicine, and that the pen must be properly discarded after the last dose.
What if my pen has been frozen?
The Mounjaro, Wegovy and Ozempic leaflets all say not to use a pen that has been frozen. Your pharmacist can tell you what to do next.
Supply
Jabwise tells you when to reorder.
Set when your next order is due and how often it repeats, then choose when you’d like the nudge: on the day, or up to 14 days before. The reminder never names your medicine on the Lock Screen.
Sources
- Mounjaro KwikPen patient leaflet
- Wegovy FlexTouch patient leaflet
- Zepbound prescribing information
- Ozempic patient leaflet
General information, not medical advice. Follow your prescriber’s guidance.
Getting real advice
We’re not doctors. This page sums up what the NHS and the official medicine information say, and can’t tell you what’s right for your body: your prescriber’s instructions and the leaflet in your box come first. More in our terms.
- Quoted from official sources, each one linked
- Sources checked 12 October 2026
- No dosing advice; your prescriber comes first
- A pharmacist, your doctor or NHS 111If you’re not sure how to use your medicine, or a side effect bothers you or won’t go away. NHS 111 if you think you might be having serious side effects, or you’ve used too much.NHS: SemaglutideNHS: TirzepatideNHS 111 online
- Report a side effectAnyone can, not only doctors.Yellow Card (UK)MedWatch (US)