How many clicks is 3.75mg on a 5mg Mounjaro pen?

Why does 3.75mg come up if it's not a licensed step?

The Mounjaro KwikPen is a continuous-delivery device, not a dial-and-set system. It clicks as the plunger advances, making the audible count a rough measure of how far the dose has been administered. Because each click represents 0.02 mL, and tirzepatide in the 5mg pen is formulated at 25 mg/mL, you can work out any volume mathematically. Three-point-seven-five milligrams is 0.15 mL, and 0.15 mL divided by 0.02 mL per click gives 160 clicks.

So where does the number come from clinically? Some patients arrive at a conversation about 3.75mg because their prescriber is managing a slower titration than the standard four-week schedule, perhaps to manage nausea or GI sensitivity. Others have read about it online and want to understand what they're actually injecting. Both are reasonable questions. The important thing is that any adjustment to the schedule in the Mounjaro SmPC is a clinical decision, made by your prescriber, not something to calculate independently at home. If you'd like to understand how 3.75mg compares across different pen strengths, that page goes further into the maths.

The licensed titration for tirzepatide, as described on the NHS tirzepatide page, begins at 2.5mg for the first four weeks, then steps to 5mg, and so on up to the 15mg maintenance dose if tolerated. A 3.75mg mid-step is not part of that published schedule, which is worth knowing before you start clicking.

What exactly happens inside a 5mg KwikPen when you press the button?

The Mounjaro 5mg KwikPen contains enough solution for four weekly 5mg doses, 3 mL in total. Each time you complete a full 5mg injection, you've advanced the plunger by 0.2 mL. The audible click mechanism is there partly as reassurance that the pen is working, and partly to let patients and carers track progress during the injection, which takes around 10 seconds of held pressure at the skin.

Counting clicks to land on exactly 3.75mg requires stopping mid-injection, which the pen is not designed for. Attempting to stop at a specific click count mid-press is unlikely to be accurate and is not how the device is intended to be used. If a half-dose or intermediate dose has been prescribed, your prescriber or pharmacist will explain the method, it may involve a different pen strength or a clinical protocol specific to your situation. For a fuller picture of what the 5mg pen holds across all four doses, this breakdown of the total click count in a 5mg pen covers it clearly.

Storage matters too. Keep the pen refrigerated between 2°C and 8°C, and check the Patient Information Leaflet for the permitted room-temperature window before travel, the leaflet is the definitive source, not any figure quoted online.

How does 3.75mg on a 5mg pen compare with other pen strengths?

The click-per-mL ratio is the same across all Mounjaro KwikPen strengths: 0.02 mL per click. What changes is the concentration of tirzepatide per mL. The 5mg pen is formulated at 25 mg/mL; the 7.5mg pen at 37.5 mg/mL; the 10mg pen at 50 mg/mL; and so on up to 15mg. This means that 3.75mg drawn from a 7.5mg pen would require a different click count than 3.75mg from a 5mg pen, because the solution is more concentrated.

To illustrate: on a 7.5mg pen (37.5 mg/mL), 3.75mg equates to 0.10 mL, which is 50 clicks, less than a third of the count on the 5mg pen. If you're doing this maths because you're unsure which pen your prescription covers, this page on 5mg administered from a 7.5mg pen walks through the same logic for a different common scenario. And if what you're actually trying to work out is the volume in millilitres rather than the click count, the mL equivalent for 3.75mg is answered separately.

Pricing for Mounjaro in the UK varies by pen strength and provider. For context on what private treatment typically involves, the Mounjaro cost page sets out what's generally included in a legitimate private prescription.

Should you be counting clicks at all, or is there a better question to ask?

Honestly, for most patients the click count is background knowledge rather than something to act on. The KwikPen is designed so that a full press of the button delivers one complete prescribed dose. If your dose is 5mg, you press and hold until the injection is done. The clicks confirm the pen is functioning; they are not a user-adjustable control.

If you're counting clicks because your dose feels uncertain (perhaps you've transferred from another provider and want to check what you were given, or you're mid-titration and feel the last injection was shorter than expected) the right move is to contact your prescriber or pharmacist. That's not a bureaucratic hoop; it's how these medicines are meant to be used. A quick message through your prescriber's aftercare channel will resolve it faster than any calculation.

The question our prescribers hear regularly is: "I'm not sure my last injection gave me the full dose." If that resonates, a clinical conversation matters more than click arithmetic. You can also browse common questions about Mounjaro or get in touch with the team directly. If you're new to tirzepatide altogether and want to understand what the 5mg pen is for in the titration journey, that page gives a grounded overview. For those still working out whether treatment is right for them, a look at weight-loss treatment options is a useful starting point before booking a consultation.