1.25mg Mounjaro: the dose that sometimes appears on prescriptions

Step 1: where 2.5mg begins and why no lower dose exists

Mounjaro is a dual GIP and GLP-1 receptor agonist, it activates two gut-hormone pathways that regulate appetite and blood-sugar handling. Activating those pathways can cause nausea, particularly in the early weeks, which is exactly why the licensed schedule starts at the lowest available strength rather than jumping straight to a dose with full therapeutic effect.

The 2.5mg pen is explicitly described in the Mounjaro SmPC as a starter dose for tolerability, not as a maintenance or weight-loss dose. Prescribers typically hold patients here for four weeks, then step up. If you come across a reference to 1.25mg, a strength sometimes cited in non-UK sources, social-media posts, or pre-market trial summaries, it is not a strength you would be dispensed by a GPhC-registered UK pharmacy. The NHS medicines page for tirzepatide sets out the UK-licensed range clearly: 2.5, 5, 7.5, 10, 12.5 and 15mg.

That said, the 2.5mg pen is doing real work even if the number looks modest. Your system is adjusting to a new mechanism of action, and for most people that adjustment period is worth taking seriously rather than rushing through.

Step 2: how the titration sequence is meant to unfold

Once the 2.5mg phase is complete, the prescriber (not the patient) decides when and whether to move up. The standard pattern, drawn from the licensed schedule, is a step every four weeks: 2.5mg to 5mg, then 7.5mg, and so on up to the maximum 15mg. The prescriber's job at each review is to weigh tolerability against progress, which is why clinical re-review before every dose increase matters.

At a private service like nume, that means providing evidence of your current dose and weight before each step up, a real person checks the picture, not an automated system. For context on how results build across the dose ladder, the 5mg Mounjaro page covers what to expect once the starter phase is behind you.

One practical note on timing: if you're planning your first order around a bank holiday or Monday dispatch cut-off, the same-day dispatch window (order by 12pm, Monday to Friday) is worth factoring in, a Friday order placed after noon ships on Monday. Small detail, but relevant if you're counting weeks between doses.

Step 3: clinical suitability, who the prescriber is assessing

Mounjaro's UK weight-management licence covers adults with a BMI of 30 or above, or 27 and above alongside at least one weight-related condition such as high blood pressure, type 2 diabetes, dyslipidaemia or obstructive sleep apnoea. Lower BMI thresholds apply for certain ethnic backgrounds under NICE's appraisal of tirzepatide (TA1026). BMI alone, though, doesn't determine what a prescriber decides, contraindications, existing medicines and medical history all form part of the assessment.

Mounjaro is not recommended during pregnancy, breastfeeding or if you're trying to conceive, and it is not licensed for under-18s. A history of pancreatitis or medullary thyroid carcinoma requires specific prescriber discussion before treatment is considered. For a fuller picture of who tirzepatide is intended for, the tirzepatide overview covers the eligibility criteria in more detail, and our clinical team background explains how prescriptions are reviewed at nume.

What to do if you want to understand costs or next steps

Mounjaro is a prescription-only medicine, so price and access are linked, any legitimate supply includes a clinical assessment. If you want to understand how private treatment is priced and what a transparent, all-inclusive cost looks like, the Mounjaro cost guide lays that out honestly without hidden fees. And if you're already on treatment and want to make the most of each dose, the guide to maximising Mounjaro weight loss covers the lifestyle factors that matter alongside the medicine.

The right starting point for anyone considering Mounjaro is a proper consultation, one where a prescriber reads your answers, not software. Our clinical lead's profile gives a sense of the standard that review is held to. When you're ready, you can speak to our prescribers through a free consultation, with same-day clinical review if you apply on a working day.