Mounjaro for weight loss: reaching the highest dose, step by step

Step 1: why treatment opens at 2.5mg, not 15mg

When your Mounjaro pen arrives (tracked by DPD, in a plain unbranded box, refrigerated in a purpose-designed cool liner) the first pen you open is 2.5mg. That might feel underwhelming if you have read about 20% weight loss in clinical trials, but the starting dose exists for a specific reason: it is a settling-in period for your digestive system, not a therapeutic target. Tirzepatide slows gastric emptying and acts on two gut-hormone receptors (GIP and GLP-1) simultaneously, which is why nausea, particularly in the early weeks, is the side effect people most commonly report. Beginning at 2.5mg gives your body time to adapt before the dose climbs.

Your prescriber sets the pace. The licensed schedule moves in 2.5mg increments (2.5mg, then 5mg, then 7.5mg, and so on) with a minimum of four weeks at each level. If a particular dose is causing significant side effects, the right move is to stay there longer rather than push ahead. That decision sits entirely with your clinician, informed by how you are getting on. You can read more about the full titration sequence on the Mounjaro dose for weight loss page.

Step 2: what happens between 5mg and 15mg

Most people will spend the better part of a year moving through the intermediate strengths: 5mg, 7.5mg, 10mg and 12.5mg. This is where the majority of the clinical work happens. Side effects are most noticeable around dose increases and tend to settle within one to two weeks as the body recalibrates. The 10mg and 12.5mg doses are often where patients feel a sustained reduction in appetite alongside improving tolerability, and some people reach a point at which their prescriber and they agree together that a middle dose is their personal maintenance level, rather than pressing on to 15mg.

Pressing on to the maximum is not automatically the goal. The licensed guidance, reflected in NICE's appraisal of tirzepatide (TA1026), is to use the highest tolerated dose rather than the highest available one. If you are unsure where your own journey might land, our page on what the best dose of Mounjaro for weight loss looks like walks through how that decision is made in practice. That conversation belongs with your prescriber.

For a sense of how the different strengths compare in practice, the Mounjaro 5mg page covers what patients often experience at one of the most common early steps.

Step 3: reaching 15mg, the evidence behind the maximum dose

When 15mg is reached and tolerated, it is the ceiling. Our page covering what the highest dose of Mounjaro is explains why the MHRA's UK licence does not include any strength above 15mg for weight management, and there is no approved route to go higher. What the evidence does show at this dose is substantial. In the SURMOUNT-1 trial (2,539 adults with obesity followed over 72 weeks) participants taking 15mg lost an average of around 20–21% of their starting body weight, according to the SURMOUNT-1 paper published in the New England Journal of Medicine. That figure applies to people who remained on treatment; individual results vary depending on diet, activity and other health factors.

Reaching 15mg also carries a practical cost consideration. Private treatment pricing changes as the dose rises. The Mounjaro prices page sets out what to expect at different strengths, including how Eli Lilly's September 2025 list-price changes affected the market. It is worth reading before you plan your budget for the longer term.

One question our prescribers hear regularly: what if 15mg is still not producing enough progress after six months? NICE's guidance suggests reviewing continuation if weight loss remains below 5% at the highest tolerated dose at that point, a clinical conversation, not a reason to stop without speaking to your team first.

Who reaches 15mg, and who stays lower

Not everyone will get to 15mg, and that is not a failure. The licensed indication for weight management covers adults with a BMI of 30 or above, or 27 and above alongside a weight-related health condition such as high blood pressure, type 2 diabetes or obstructive sleep apnoea. Within that group, where someone ends up on the dose ladder depends on tolerability, response, and clinical judgement.

If you are transferring to nume from another provider and are already on a higher dose, evidence of your current treatment is reviewed before any continuation or increase is approved. The same applies to dose increases generally: each step up requires a prescriber to review your progress, not just a repeat click. To understand how the full process works at nume and whether treatment might suit you, our Mounjaro overview covers eligibility in detail, and the weight-loss treatment page explains how the different options compare. Our clinical team is available to answer questions seven days a week.