What doses does Mounjaro come in, and how does the schedule work?

Why does Mounjaro start at 2.5 mg when the trials used higher doses?

The 2.5 mg pen is where every course of Mounjaro begins, and it surprises some people. The large SURMOUNT-1 trial, published in the New England Journal of Medicine, reported average weight reductions of around 20–21% at the 15 mg dose over 72 weeks. Those results came after a careful titration period, not from jumping straight to the top strength.

The reason for starting low is practical. Tirzepatide slows the movement of food through the stomach and powerfully suppresses appetite. Introducing that effect gradually (at 2.5 mg) gives the gastrointestinal system time to settle, which makes nausea, vomiting and discomfort far less likely to derail treatment early on. Think of the first four weeks as calibration, not treatment in the full sense.

After that, the prescriber typically steps the dose up every four weeks: 2.5 mg → 5 mg → 7.5 mg and so on. The ceiling is 15 mg. Some people find a comfortable, effective dose well before then and stay there. Others work through all six strengths. There is no universal right answer, it depends on how your body responds and what side effects, if any, you experience. The NHS medicines page for tirzepatide gives a patient-level overview of how the medicine works and what to expect.

One practical note: if you are planning a holiday or your order tends to fall around payday, it is worth thinking ahead so a dose increase does not coincide with a lapse in supply. Your prescriber can help you plan.

What milligram options are available, and how is each pen different?

Each of the six Mounjaro strengths comes as a pre-filled KwikPen. The pen contains four doses, one for each week of a four-week supply. All six strengths share the same injection volume; the concentration of tirzepatide changes, not the amount of liquid you inject. That matters for practical storage and handling: the process of injecting looks identical whatever dose you are on.

For readers wondering about the volume measurements behind each pen, the Mounjaro doses in ml page goes into that detail. What dosage Mounjaro goes up to (meaning the ceiling and what happens at the top of the schedule) is covered separately on the maximum Mounjaro dose page.

The KwikPen is designed to be used at the abdomen, thigh or upper arm, rotating injection sites each week. Storage is refrigerated at 2–8°C. For the exact room-temperature window and shelf life once out of the fridge, the Patient Information Leaflet and Mounjaro SmPC are the correct reference, prescribers at nume direct patients there rather than stating a figure that could become outdated.

The six strengths are all part of a single licensed product range. Tirzepatide (the active ingredient in Mounjaro) is also discussed on the tirzepatide strength page if you have seen both names used and want to understand the relationship.

Who can be prescribed each strength, and what does eligibility actually look like?

Mounjaro is licensed in the UK for weight management in adults with a BMI of 30 or above, or a BMI of 27 or above alongside at least one weight-related condition such as high blood pressure, high cholesterol, type 2 diabetes or obstructive sleep apnoea. Lower BMI thresholds apply for some ethnic backgrounds under UK clinical guidance. A BMI figure alone does not guarantee a prescription, the prescriber reviews the full clinical picture.

NICE's appraisal of tirzepatide (TA1026) sets out the criteria for NHS access separately; the thresholds and conditions that apply on the NHS are more specific than the licence, and the rollout is phased. Private treatment through a regulated pharmacy such as nume's service follows the licensed eligibility criteria rather than the NHS phased criteria, subject to a prescriber's individual assessment.

Each dose increase is also a clinical decision, not automatic. If you are considering the 5 mg pen specifically, or want to understand how the five-dose transition works in practice, those pages go into more detail. The prescriber reviews your response at each stage, including your weight, any side effects, and whether continuing at the current or higher strength is appropriate. At nume, that review happens before every repeat order, not just at the start.

Does the dose affect what side effects you might notice?

Generally, yes. The most common side effects of Mounjaro are gastrointestinal: nausea, diarrhoea, constipation, indigestion, burping, and sometimes vomiting. These are most noticeable when starting or after a dose step-up, and they tend to ease within a week or two as the body adjusts. Going slowly through the titration steps is one of the main tools for managing them.

At higher doses (10 mg, 12.5 mg and 15 mg) some people experience more pronounced GI effects than they did at lower strengths. That is not universal, and many people tolerate the higher doses well. The 15 mg dose produced the strongest trial results, but it is not always the most practical dose for every individual.

More serious but infrequent reactions include acute pancreatitis. The symptom to take seriously is severe, persistent abdominal pain that radiates to the back, with or without vomiting, that warrants urgent medical attention. Any suspected side effect can be reported through the MHRA Yellow Card scheme, and patients are encouraged to use it. Questions about how a specific dose is affecting you belong with your prescriber, not a webpage. If you are already a patient and want to discuss your dose, the contact page has details for our aftercare team, who are available seven days a week.