The Mounjaro Click Chart Explained: Reading Your KwikPen Doses

What the official pen guidance says about dose selection

Eli Lilly's Summary of Product Characteristics for Mounjaro (published on the electronic Medicines Compendium and referenced by the NHS tirzepatide medicines page) states that each KwikPen contains 3 ml of solution and is pre-set to deliver doses by dialling a numbered selector. The pen cannot be used to deliver a dose outside its programmed range, which is a deliberate safety feature. Treatment begins at 2.5 mg, with the first pen's job being to let your body adjust to the medicine before any therapeutic titration happens. Subsequent doses step up in 2.5 mg increments, typically at four-week intervals, on your prescriber's instruction.

The click chart maps this onto something concrete: each distinct click of the dial represents a defined increment of the plunger mechanism. Because the cartridge concentration is fixed at 5 mg/ml, the relationship between clicks, dose in milligrams and volume in millilitres is consistent across all six strengths. A 2.5 mg dose, for example, corresponds to 0.5 ml; a 5 mg dose to 1 ml; and so on up to 15 mg at 3 ml (the full cartridge). The chart printed in some patient guides (and the KwikPen click chart reference on our site) makes these relationships visible at a glance.

One practical point worth knowing: after the final dose, the pen will show zero in the dose window and the plunger will be fully depressed. This is normal. Dispose of used pens in a proper sharps container rather than household waste.

How the click-to-ml mapping works across all six doses

Because the cartridge concentration is standardised, you can cross-reference the click count against the volume window to verify you have dialled correctly. This is what the click chart is primarily for. The six UK dose strengths and their corresponding cartridge volumes are consistent pen to pen, Eli Lilly manufactures only one cartridge concentration for Mounjaro, which means the chart is the same whether you are on your first pen or your fifteenth.

A fuller breakdown of this mapping, including the click counts themselves, is set out in our tirzepatide click chart guide, which covers the same information under the medicine's generic name as it appears in clinical references. The key practical habit is to check both the audible click count and the dose window volume before pressing the injection button. If the two readings do not match what your chart shows for your prescribed dose, do not inject, contact your prescriber or our aftercare team.

For information on the broader cost picture around treatment, our Mounjaro price guide covers what private prescriptions typically include in the UK. Worth reading before you start, so there are no surprises.

Common questions about clicks, volumes and what to do if something looks wrong

The question our prescribers hear most often about the click chart is whether a missed or double click invalidates the dose. The short answer is: if the dose window shows the volume that matches your prescribed dose, the pen has registered correctly regardless of what you thought you heard. The volume window is the more reliable indicator, the click is tactile feedback, not a measurement.

If the dose window shows less volume than expected at your usual dose, the most likely explanation is that the pen is close to its last dose. The Mounjaro clicks chart guide explains how to identify how many doses remain. If the window shows zero and the pen has not been previously used, this would be a manufacturing defect; contact our pharmacy team via the contact page and we will arrange a replacement under our clinical aftercare process.

One scenario that trips people up: leaving the pen out of the refrigerator. Mounjaro must be stored at 2–8°C, and the guidance on what to do if your pen has been left out overnight is worth bookmarking before you need it. A pen stored incorrectly may still look normal, so the click chart alone won't tell you whether the medicine is still viable, storage conditions matter separately from dose mechanics.

Putting the chart in context: clicks are a guide, not the whole picture

The click chart, however detailed, covers the mechanical side of using the pen. The clinical side (which dose you should be on, whether a titration is appropriate, how to manage side effects) sits with your prescriber. NICE's appraisal of tirzepatide, TA1026, confirms that Mounjaro is a prescription medicine intended to be used alongside reduced-calorie eating and increased activity, under ongoing clinical supervision. The chart helps you inject the right amount confidently; it does not replace the clinical relationship.

Used as intended, the click chart is a reassuring double-check that takes about five seconds before every injection. Most patients find that after a few weeks the dose window confirmation becomes second nature, a bit like checking the hob before leaving the house. That brief pause before pressing the button is genuinely useful, particularly in the first few months when the dose may still be stepping up.

If you are not yet on treatment and want to understand what the full process looks like, from how the injection itself works to what to expect at each stage, our clinical team reviews every consultation personally. You can read more about how we work on the about us page, or start the process directly whenever you are ready.