6.25mg Mounjaro: the dose that doesn't appear on UK packaging

Where does the figure 6.25mg come from?

This is a question our prescribers hear most weeks, and it usually traces back to one of a few places. In the United States, tirzepatide pens for weight loss are marketed under the brand name Zepbound, and some US-market materials or online forums describe doses in slightly different terms or reference compounded formulations. Compounded tirzepatide is not licensed in the UK; the only legal route to tirzepatide here is through the licensed Mounjaro KwikPen range, sourced through the authorised UK supply chain.

The 6.25mg figure also surfaces when someone halves a 12.5mg pen, either in an attempt to titrate more slowly than the licensed schedule allows, or to reduce cost. This is not a supported approach. The KwikPen is designed as a fixed-dose device; the accuracy of an improvised half-dose cannot be guaranteed, and using the pen in a way not described in its instructions raises both dosing and safety concerns. The full licensed Mounjaro dose range covers why each strength exists and how the schedule is designed to work.

A third possibility is that 6.25mg appears in early-phase clinical research, where tirzepatide was tested across a wider dose range before the six licensed strengths were settled. That context is academic; it does not apply to how Mounjaro is prescribed today in the UK, as confirmed by the Mounjaro SmPC published on the electronic Medicines Compendium.

Why does the licensed schedule use these specific steps?

The six-step schedule (2.5, 5, 7.5, 10, 12.5 and 15mg) was established through the SURMOUNT clinical programme and refined in Eli Lilly's regulatory submissions. The starting dose, 2.5mg, exists primarily to let the gastrointestinal system adjust; nausea and related symptoms are most likely in the early weeks, and a low starting point reduces their severity. If you want to understand what to expect at that opening stage, our 0.25 Mounjaro page explains what the earliest dose involves and how it fits into the overall schedule.

Each subsequent step roughly doubles the preceding increment. The 2.5mg gap between steps was judged to give most people a manageable increase while still moving toward the doses where the largest weight reductions were seen in trials. In the SURMOUNT-1 trial, published in the New England Journal of Medicine, average weight reduction at the 15mg dose reached around 20–21% over 72 weeks, a result achieved at the top of the schedule, not at the earlier steps.

A prescriber might hold a patient at any step for longer than four weeks if side effects are significant, or move through steps more slowly. What a prescriber will not typically do is create a 6.25mg dose that sits outside the licensed framework. If someone is struggling at 12.5mg, the clinical conversation is about whether 12.5mg is the right dose for them, not about improvising a fraction of it. For a practical look at how the intermediate steps behave, the 5mg Mounjaro page gives a sense of what an early maintenance step involves.

What does this mean if you're thinking about starting Mounjaro?

If you came to this page because you were trying to find a lower or more granular dose than the licensed schedule offers, the honest answer is that the schedule itself is already designed with caution at its core. Our 1.25 mg Mounjaro page explains where that strength sits in the context of the schedule and why the licensed starting point is already set with tolerability in mind. Slow titration is built in, not something you need to engineer by sourcing an unlicensed strength.

What matters practically is that your prescriber reviews how you're responding at each step. Dose increases on a private prescription, including through a service like ours, require clinical evidence of how the current dose is going, that review is a safety feature, not bureaucracy. If a prescribed dose is causing side effects you're struggling with, the right move is to contact your prescriber rather than adjust the dose yourself.

Cost sometimes drives people toward unconventional dose approaches. It's worth knowing that the cost of Mounjaro varies by strength, and that the lower-dose pens typically cost less than the higher ones, so the licensed schedule already means earlier stages carry a lower price tag than the maintenance doses.

NICE's recommendation for tirzepatide, published as Technology Appraisal TA1026, sets out the clinical criteria under which tirzepatide is recommended for NHS use. Private prescribing follows the licensed indications but operates outside those NICE thresholds, which is why a full clinical assessment comes before any prescription. If you'd like to understand whether Mounjaro could be appropriate for you, the place to start is a free consultation with our prescribers.