What BMI do you need to get Mounjaro on a private prescription?

Does your BMI meet the private Mounjaro threshold?

The UK licence for Mounjaro (tirzepatide, made by Eli Lilly) covers adults with a BMI of 30 or above, used alongside a reduced-calorie diet and increased physical activity. If your BMI sits between 27 and 29.9, you can still qualify provided you have at least one weight-related condition. Conditions that count include type 2 diabetes, hypertension, dyslipidaemia (raised cholesterol or triglycerides), obstructive sleep apnoea and cardiovascular disease. The 27 threshold with a weight-related condition catches a meaningful group of people who would otherwise assume they don't qualify.

One thing worth clearing up: some people believe you need a BMI of 35 or 40 to be considered. That figure comes from the NHS eligibility criteria, which are deliberately stricter. Private prescriptions follow the licensed indication, so the bar is genuinely lower. UK guidance also recognises that for people from South Asian, Chinese, Middle Eastern, Black African or African-Caribbean backgrounds, BMI thresholds are typically reduced by 2.5 kg/m², so the starting threshold can effectively be 27.5 rather than 30, or 24.5 rather than 27 with a comorbidity. The NHS BMI calculator is a quick way to check your figure before you do anything else.

BMI is a population-level tool with real limitations. It says nothing about where fat is distributed or what's going on metabolically. Prescribers know this, which is why the consultation includes more than a number.

What does the NHS require, and why is it different?

NICE recommended tirzepatide for NHS use in December 2024 (Technology Appraisal TA1026), but the NHS eligibility criteria are phased and considerably narrower than the private-prescription threshold. Currently, NHS access requires a BMI of at least 40 alongside four or more of five specific conditions: high blood pressure, dyslipidaemia, obstructive sleep apnoea, cardiovascular disease, and type 2 diabetes. From around June 2026, the cohort expanded to include people with a BMI of 35 to 39.9 also carrying four or more of those conditions.

The practical upshot is that the majority of people who would qualify for a private prescription do not yet meet the NHS threshold. Those who do meet NHS criteria still face waiting lists and a requirement to engage with a structured wraparound support programme. Neither thing is a criticism of the NHS, it's rationing based on clinical severity, which is a defensible position. It does mean that for many people, a private route is the realistic one right now.

If you're curious whether high blood pressure specifically puts you over the threshold, our page on Mounjaro and high blood pressure covers both the eligibility angle and the safety considerations.

What actually happens when the prescriber reviews your BMI?

Submitting a BMI figure is the start of the process, not the end. At nume, a GPhC-registered Independent Prescriber reads your consultation the same day, a real clinician, not a decision algorithm. They're checking several things beyond the number itself: whether any conditions make Mounjaro unsuitable (a history of pancreatitis, for example, or certain gut conditions), what other medicines you take and whether interactions are a concern, and whether the picture you've described is consistent with the eligibility criteria.

For people with a BMI right at the boundary, the qualifying condition matters a great deal. The prescriber will consider whether the condition documented genuinely meets the clinical description in the licence. Exact BMI questions (including borderline figures) are covered in more detail in our companion guide. It's also worth knowing that women using oral contraceptives are advised to add a non-oral method for the first four weeks of Mounjaro treatment and for four weeks after each dose increase, as the medicine can affect how the pill is absorbed; your prescriber will flag this at consultation.

For a clear overview of what the treatment itself involves, our Mounjaro treatment page explains the KwikPen, the dosing schedule and what to expect week by week. Questions about cost are covered separately on our Mounjaro pricing page.

What if your BMI is lower than 27?

Below a BMI of 27, Mounjaro is not within its licensed indication for weight management in the UK. This is a hard line in the SmPC, and a responsible prescriber won't cross it, regardless of how someone feels about their weight or what they've read online. It's worth saying plainly: Mounjaro is not assessed or licensed for cosmetic weight loss, and the MHRA is clear on this point.

The pages covering a BMI of 28 and a BMI of 25 address specific boundary scenarios in detail, because these questions come up often. If your BMI is under 27 and you're concerned about your weight, the most useful step is a conversation with your GP about what options sit within the appropriate clinical pathway for you. You can also explore other evidence-based weight management approaches that may be relevant at a lower BMI.

If you've confirmed your BMI and want to find out whether you're suitable, check your eligibility with our prescribers, the consultation is free and reviewed the same day.