How to Get Medicine Out of a Mounjaro Pen (UK Guide, October 2026)

01 · The core answer

How the Mounjaro pen delivers your dose

The medicine leaves the pen only through the attached needle, when you dial the dose and press the injection button. Mounjaro is injected under the skin once a week, on the same day each week, at any time of day, with or without food.¹ Each KwikPen contains four weekly doses.¹³

You turn the dose knob until the indicator shows the correct dose in the window.

Rotate the injection site each week.¹ If you are new to the pen, our needle removal guide and the stuck-needle help page cover the practical snags.

02 · Why liquid remains

Why there seems to be medicine left in the pen

Each Mounjaro KwikPen is designed and licensed to deliver exactly four weekly doses, so liquid left in a finished pen is not another usable dose.

Altering doses outside the licence means unknown dosing accuracy and no safety data. For more detail see our guides on the remainder in the pen and fifth-dose questions.

03 · Getting your supply

Getting a pen of your own

If you are looking for more medicine because a pen seems to run short, the safe route is a correctly dispensed supply. The Mounjaro pen starts at £169.99 per month for 2.5mg, and your first 2.5mg pen costs £129.99 with code FIRST40. An automatic £25 reorder discount applies to every future order (code DOSE25). You can start your free consultation, and a GPhC-registered prescriber reviews every order. Needles, a sharps bin and injection guidance come with every order, and our team can talk you through the pen. You can also buy Mounjaro from our official LillyDirect supply.

04 · Why not extract liquid

Why you should never extract medicine from the pen

Opening the pen or drawing liquid out with a syringe is not part of the licensed way of using it. The dose is set by the dial and confirmed in the window, so any other method means unknown dosing accuracy.¹

Forcing the mechanism can also damage the pen. Dispensed prescription medicines cannot be returned except faulty, damaged or wrong items, and you must contact us within 3 days.

Related reading: getting the rest out of the pen, excess medicine in the pen and whether a pen can last five weeks.

05 · Dose, clicks and strength

Clicks, doses and dose strengths

Click counting is not a method for choosing a dose. The pen comes in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹

Everyone starts on 2.5mg once a week. After at least 4 weeks the dose rises to 5mg, then can step up by 2.5mg at minimum 4-week intervals to a maximum of 15mg, depending on response and tolerability.¹ If you need a different dose, ask your prescriber rather than adjusting the pen yourself.

06 · Missed doses and day changes

Missed doses and changing your injection day

If you miss a dose, take it as soon as you can within 4 days (96 hours) of the scheduled time, then carry on as usual. If more than 4 days have passed, skip it and take the next dose on your normal day. Never take two doses within 3 days of each other.¹

You can change your injection day as long as at least 3 days (72 hours) have passed since your last dose.¹ A missed dose is never a reason to draw extra liquid from a pen.

07 · Storage and disposal

Storing the pen and disposing of needles

Keep pens in a fridge at 2–8°C and never freeze them. Once in use, a pen can be kept out of the fridge at a temperature not above 30°C for up to 30 days after first use, and must then be thrown away. Keep the cap on to protect it from light, and never use a pen that has been frozen.¹

Dispose of used needles in a sharps bin, which is included with every order. Ask your pharmacy about returning a full sharps bin locally. After four doses, or 30 days (not above 30°C) once in use, throw the pen away even if liquid is visible. For a leak at injection, see Mounjaro injection leaked out, and for the final dose see our last dose guide.