What are the doses of Mounjaro, and how does the schedule work?

You've just been prescribed Mounjaro, here's what that first pen actually means

The prescription has come through and you're holding a 2.5 mg KwikPen. A fair question at this point: is this it? The first dose feels small because it is meant to. Tirzepatide slows gastric emptying and reduces appetite via two gut-hormone receptors, and starting at full therapeutic strength would cause significant nausea for most people. So 2.5 mg is the adjustment period, four weeks to let your digestive system get used to the medicine before anything increases.

Most people notice little in the way of weight change during this opening month. That is normal and expected. The NHS patient information for tirzepatide confirms this staged start, and the Mounjaro SmPC on the eMC sets out the full licensed schedule. Once the four weeks are up, a prescriber reviews your experience and, if you've tolerated it well, moves you to 5 mg. You can read more about what sits inside the 5 mg step specifically if that's where you're heading next.

One thing worth knowing early: you inject once a week, same day each week, into your abdomen, thigh or upper arm, rotating the site each time. Every pen contains four weekly doses.

How the step-up schedule unfolds, and why it isn't always a straight line

After 5 mg, the pattern continues in 2.5 mg increments: 7.5 mg, 10 mg, 12.5 mg, and finally 15 mg. In the SURMOUNT-1 trial (which involved 2,539 adults with obesity and ran for 72 weeks) participants on 15 mg saw an average body-weight reduction of around 20–21%, the highest recorded for any licensed weight-loss medicine in the UK at the time. Those results informed NICE's recommendation of tirzepatide in December 2024.

But the path to 15 mg is not guaranteed, and it isn't meant to be. If side effects at a given step are uncomfortable, your prescriber may pause the titration and keep you on your current dose for another four weeks. Some people settle at 10 mg or 12.5 mg and do very well there. The goal is the highest dose you tolerate, not the highest dose on the list. If you want a detailed breakdown of what the evidence says about each maintenance level, our page on Mounjaro maintenance doses covers that specifically.

Dose increases are always a clinical decision. At nume, a GPhC-registered prescriber personally reviews each repeat order before it is dispensed, the schedule moves at the pace your clinical picture supports. If you're curious how each of the six strengths fits into the wider picture, our guide to the different doses of Mounjaro walks through what each one represents and when it typically comes into play. Understanding the full dosage framework for Mounjaro can help you have a more informed conversation with your prescriber.

Side effects that tend to follow dose changes, and when they ease

Nausea, loose stools, constipation, indigestion and burping are the most common reactions, and they are most likely to appear in the first week or two after starting or stepping up. For most people they settle as the body acclimates; they rarely stay at the same intensity for more than a fortnight at any given dose. The NHS tirzepatide page lists these alongside less common effects worth watching for.

A smaller number of people experience more significant symptoms. Severe, persistent stomach pain that radiates to the back (with or without vomiting) should be treated as urgent: get medical help promptly, as this can be a sign of pancreatitis. The MHRA highlighted acute pancreatitis as a known but infrequent risk for GLP-1 medicines in a Drug Safety Update published in January 2026, and it is the reason prescribers ask about your history of pancreatic problems before starting treatment.

If you're thinking about cost while weighing up the schedule, it is worth knowing that private treatment pricing varies by dose and provider. Our weight-loss treatment overview gives factual context on how private GLP-1 treatment is priced in the UK, without the marketing gloss.

A clinical decision, not a packaging choice

One point that sometimes confuses people new to Mounjaro: the six strengths are not interchangeable options you choose between. The schedule is a clinical protocol. Your prescriber decides the current step based on your tolerance, your progress and your health picture as a whole. Eligibility for treatment requires a BMI of 30 or above, or 27 or above with at least one weight-related condition such as high blood pressure, high cholesterol, obstructive sleep apnoea or type 2 diabetes. Lower BMI thresholds can apply for some ethnic backgrounds under UK guidance.

Tirzepatide is the only dual GIP and GLP-1 receptor agonist licensed for weight management in the UK, a different mechanism from semaglutide-based treatments. Our tirzepatide dosing page explores that distinction further for people comparing options. For a broader look at how Mounjaro fits into the treatment landscape, the Mounjaro overview is a good starting point.

If you've read this far and you're wondering whether you'd be suitable for treatment, a prescriber at nume can review your consultation the same day. There's no referral needed, no waiting list, and the assessment is free. Check your eligibility and start your free consultation.