Mounjaro strengths: what each dose is for and how the schedule works

You've just been prescribed Mounjaro, and the pen in front of you says 2.5 mg

It can be disorienting. You've read about people losing significant weight on tirzepatide, and the pen you're holding seems a long way from the doses those results are linked to. That's entirely normal to wonder about, and the answer is straightforward: the 2.5 mg strength is not intended to produce substantial weight loss on its own. Its job is to introduce tirzepatide to your system gradually, reducing the likelihood of nausea, vomiting or digestive discomfort that can occur when the medicine is started at a higher dose. Most people spend four weeks at 2.5 mg before moving to the next rung.

All six Mounjaro strengths use the same KwikPen format. Each pen holds four doses, and the pen for each strength is colour-coded to reduce the chance of errors. The sequence runs: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg and 15 mg, the full list, as detailed in the NHS tirzepatide medicines page. If you're wondering whether tirzepatide comes in different strengths and how they differ, what varies is both the amount of tirzepatide delivered and the clinical effect on appetite regulation and gastric emptying, which intensifies as the dose increases.

The dual GIP and GLP-1 receptor mechanism means tirzepatide works on two complementary pathways simultaneously, which is one reason the clinical evidence at higher doses looks as strong as it does. But the 2.5 mg start is deliberately conservative. Think of it as giving your digestive system several weeks to settle before the therapeutic work begins in earnest.

What the middle strengths actually do, and why most people don't stay at 5 mg

Once the starter pen is done, your prescriber will typically move you to 5 mg for another four weeks, then 7.5 mg, and so on. The question our clinical team hears fairly often at this stage is whether someone should stay at a middle strength longer, or push toward the top. The honest answer is that it depends on two things: how much weight you're losing and how well you're tolerating the current dose.

5 mg and 7.5 mg are genuine therapeutic doses, not transitional ones. Some people find meaningful appetite suppression at these levels and their prescriber may recommend staying there. The titration schedule exists to give your body time to adapt, not to rush everyone to 15 mg. If you're curious about how the mid-range doses compare in practice, our guide on which Mounjaro strength is used for weight loss goes into more detail on this.

Side effects across all strengths share a broadly similar profile, gastrointestinal symptoms (nausea, loose stools, constipation, indigestion) are the most commonly reported, and they tend to be more noticeable when a new strength is started or a dose is increased. They usually settle within a couple of weeks. If they don't, that's a conversation for your prescriber, not a reason to stop or self-adjust.

One practical note: the dose at which you get the most benefit is also the one you'll stay at long-term, called your maintenance dose. Not everyone reaches 15 mg, and that isn't a failure, it's the medicine being calibrated to you. If you'd like to think through where you might land, this page explores how prescribers approach that decision.

The 15 mg strength: what the trial data shows and what it means in practice

The SURMOUNT-1 trial, which enrolled over 2,500 adults with obesity and ran for 72 weeks, found that participants on the 15 mg dose achieved around 20–21% average body-weight reduction. That figure gets quoted a lot. It's worth being clear about what it represents: an average across a trial population, alongside lifestyle support, over roughly 18 months. Individual results vary, and no outcome can be guaranteed for any single person.

NICE's appraisal of tirzepatide, TA1026, reviewed this evidence when recommending tirzepatide for adults with a BMI of 35 or above alongside at least one weight-related condition. Lower BMI thresholds apply for some ethnic backgrounds under UK clinical guidance. The private licensed eligibility criteria are broader, adults with a BMI of 30 or above, or 27 or above with a relevant condition, may be eligible for a private prescription, subject to a prescriber's assessment.

The 12.5 mg strength sits just below the ceiling and suits people who have reached a good response at that level or who find the step to 15 mg comes with more side effects than benefit. The question of what a long-term maintenance plan looks like is something our prescribers discuss with patients as they approach the higher doses. The right strength for you isn't necessarily the highest one; it's the one your prescriber decides offers the best balance for your clinical picture.

For anyone weighing up private treatment, the treatment options page is the starting point, it covers eligibility, the consultation process, and what to expect before your first pen arrives.