Mounjaro pen doses in the UK

What Mounjaro KwikPen strengths are there in the UK?

The UK Mounjaro KwikPen comes in six strengths: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg and 15 mg. The number is the dose in each 0.6 mL injection, and every pen holds 4 of those doses¹. So a 5 mg pen holds 20 mg of tirzepatide in 2.4 mL¹.

Because each pen gives the same 0.6 mL, a higher-strength pen packs more tirzepatide into the same volume. A 15 mg pen is six times as strong per mL as a 2.5 mg pen. That matters later, when we look at why click counts shared online don't match.

The UK label dose steps are 2.5 mg once a week for 4 weeks, then 5 mg. If needed, the dose goes up in 2.5 mg steps with at least 4 weeks on each, to a maximum of 15 mg a week for adults¹. Each step is a different pen. The full schedule, and the US pens and vials, are in our tirzepatide dosage chart.

How many doses are in a Mounjaro KwikPen?

A Mounjaro KwikPen holds 4 weekly doses of 0.6 mL. The UK Instructions for Use say to throw the pen away after 4 doses, or 30 days after first use³.

Each week, the Instructions for Use describe two parts:

• Priming. Turn the knob until you hear 2 clicks and see the priming line, then push out a small amount into the air. This clears air from the cartridge³. Lilly UK says the pen allows up to 8 primes in total. Priming more often than that, or turning past 2 clicks when priming, can waste medicine and may leave you unable to dial the 4th dose⁶.
• The dose. Turn the knob until it stops and the dose icon shows in the window. That icon equals a full 0.6 mL dose³. Push in and hold for a slow count of 5.

The lines printed on the cartridge are not dose markers. The UK instructions say not to use them as dose indicators³, and Lilly UK says they don't show how many doses are left⁷.

Keep unused pens in the fridge at 2°C to 8°C, and don't freeze them. After first use, the pen can be kept out of the fridge for up to 30 days at no more than 30°C, and then it must be thrown away¹.

Is the Mounjaro "golden dose" a real dose?

No. The liquid left in a Mounjaro KwikPen after 4 doses, sometimes called the "golden dose", is not a dose. The UK leaflet says a small amount may remain after all doses have been given correctly, and tells you not to try to use it². The SmPC says any excess solution should be thrown away¹.

Why it's there, and why to leave it:

• It's there by design. Lilly UK says the pen holds enough extra liquid for priming before each injection, and that medicine left after the 4th dose is expected^4–5.
• The pen won't give it as a dose. Lilly UK says an extra full 0.6 mL dose can't be dialed, and that trying to inject leftover medicine could give an incomplete dose⁵.
• The regulator says leave it. The MHRA says that after the four doses, you should throw the pen in the bin without trying to get any remaining medicine out⁸.
• Don't move it into a syringe. The US instructions for the Mounjaro KwikPen say not to inject the leftover medicine and not to transfer it from the pen into a syringe⁹.

Can you count clicks on a Mounjaro pen for a smaller dose?

The Mounjaro KwikPen isn't licensed for counting clicks to get a smaller dose. The UK instructions describe a pen with 4 fixed doses: you turn the knob until it stops at the dose icon, which equals a full 0.6 mL dose³. The US Mounjaro KwikPen instructions say it outright: "Do not count clicks as you select the dose"⁹.

We checked the SmPC, the leaflet, the instructions and Lilly's UK answers. None of them give a click count, or a dose for any point before the dose icon^1–6,13. So we don't publish click tables or a click calculator.

Click counts shared online often disagree with each other. A few reasons, based on what the official documents do say:

• Pens differ in strength. Every pen gives 0.6 mL, but the tirzepatide in that 0.6 mL ranges from 2.5 mg to 15 mg¹. The same turn of the knob on two different pens would hold very different amounts.
• There are two versions of the pen. Lilly UK says a modified KwikPen is on the market at the same time as the original one, with a new part behind the plunger^4,13.
• Clicks have one official use. In the instructions, "2 clicks" marks the priming position³. Lilly warns that going past 2 clicks when priming wastes medicine and may leave you unable to get the 4th dose⁶.

What changed with the Mounjaro KwikPen?

Lilly has brought out a modified Mounjaro KwikPen that leaves less medicine behind after the 4th dose than the original pen. A new part sits behind the plunger. The medicine, the doses and the way you use the pen haven't changed¹³. Both versions hold priming liquid plus 4 fixed doses of 0.6 mL¹³.

• How to tell them apart: in an unused modified pen, the plunger sits further down the cartridge¹³.
• When it's finished: after 4 doses, the modified pen's plunger sits near the bottom of the cartridge. That's the sign to throw it away¹³.
• Which one you'll get: Lilly UK says the modified pens are being brought in gradually. Until stocks of the original design run out, you may get either one¹³.

Lilly UK gives no launch date for the modified pen, so we haven't given one. The current SmPC and leaflet still describe 4 doses of 0.6 mL per pen, in the same six strengths^1–2. If you're not sure which pen you have, ask your pharmacist.

Is the UK Mounjaro pen the same as in the US?

The UK and US Mounjaro KwikPens match on the basics: 4 doses per pen, in strengths from 2.5 mg to 15 mg, with 2.4 mL in each pen^1,9. In the US, Mounjaro also comes as single-dose pens, single-dose vials and multi-dose vials⁹. In the UK, the KwikPen is the only Mounjaro product listed on the electronic medicines compendium¹².

If you were using vials and switch to a pen, or the other way round, the amount you inject changes even when the mg dose doesn't. Our tirzepatide dosage chart shows vial doses in mL and units.