What weight do you need to be to get Mounjaro?

Does the licence set a specific weight, or is it always about BMI?

The short answer: the licence specifies BMI, not a body weight in kilograms. There is no single kilogram figure that unlocks Mounjaro, because a weight of, say, 90 kg means something very different at 5 ft 2 in than at 6 ft 1 in. BMI (weight in kilograms divided by height in metres squared) is the measure UK clinical guidance actually uses.

Under its UK licence, tirzepatide is approved for adults with a BMI at or above 30, or at or above 27 where at least one weight-related condition is present. The NHS BMI calculator is a practical first step if you want to check your own number before anything else, you can find it on the NHS BMI calculator page. Qualifying conditions at the 27-plus threshold include type 2 diabetes, prediabetes, high blood pressure, dyslipidaemia, obstructive sleep apnoea and osteoarthritis, among others.

UK guidance also recognises that BMI can underestimate health risk in some ethnic groups. For people from South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean backgrounds, the clinical thresholds are typically set 2.5 kg/m² lower, so 27.5 instead of 30, or 24.5 instead of 27. This is worth knowing if you are close to a threshold and wondering whether you might still qualify.

What weight do you need to be to take Mounjaro on the NHS versus privately?

The distinction matters. Accessing Mounjaro through the NHS follows NICE guidance (TA1026), which is considerably stricter than the product licence. NICE recommends tirzepatide for NHS use in adults with a BMI of 35 or above alongside at least one weight-related comorbidity. The rollout is also phased: as of mid-2026, NHS eligibility broadly requires a BMI of 40-plus with four or more qualifying conditions, or a BMI of 35 to 39.9 with four or more conditions under the second cohort activated in June 2026. Waiting lists exist on top of that.

Private prescribing follows the licensed thresholds directly: BMI 30 or above, or 27 or above with a qualifying condition. That is a much wider group. Many people come to Mounjaro through a private route precisely because they meet the licence criteria but fall short of the NHS threshold, or simply cannot wait. If you are curious about where your BMI sits relative to these cut-offs, our companion page on the weight thresholds for Mounjaro sets out the numbers side by side.

It is worth being honest with yourself here: if your BMI is currently below 27 with no qualifying conditions, Mounjaro is not licensed for you at this point. A responsible prescriber will not issue a prescription in that situation, whatever the commercial pressure to do so.

Is BMI the only thing a prescriber looks at?

No, and this is where people sometimes feel a bit deflated after calculating their BMI and assuming they are done. Meeting the BMI threshold opens the door to an assessment; it does not complete it. A prescriber reviewing a Mounjaro consultation will also consider your medical history, any medicines you currently take, and conditions that could make tirzepatide unsuitable regardless of your weight.

Mounjaro is not appropriate for everyone with a qualifying BMI. People with a personal or family history of medullary thyroid carcinoma or a condition called MEN2, a history of pancreatitis, or certain gastrointestinal conditions will need a careful clinical conversation before a prescription can proceed. The prescriber also checks for drug interactions and, for women, discusses contraception, because absorption of the oral contraceptive pill can be reduced during the first four weeks of treatment and for four weeks after each dose increase, and an additional barrier method is advised during those windows. You can read more about what to expect on the tirzepatide overview page.

People often tell us they wish they had known the consultation would be this thorough. It can feel like a lot of questions. But those questions are exactly why a face-value BMI check is not the same thing as a clinical assessment, and if you want to understand how the injection process itself works, our page covering Mounjaro jags walks through what to expect. The NICE appraisal of tirzepatide (TA1026) is publicly available if you want to read the clinical reasoning in full.

What happens if your weight changes before or during treatment?

If you are right on the edge of a threshold when you start, it is natural to wonder what happens as treatment progresses and your weight falls. Prescribers take the same approach they would with any ongoing clinical review: they look at your overall health picture, whether the medicine is producing a meaningful response, and whether continuing treatment remains clinically appropriate. NICE guidance for NHS patients notes that continuing should be reconsidered if less than 5% weight loss is achieved after six months at the highest tolerated dose.

Practical considerations change over time too. Some people ask about whether you need to taper off Mounjaro if you stop, or about which vitamins matter during treatment when appetite is reduced. These are the kinds of questions that come up at repeat reviews, and that is exactly where a prescriber who knows your history adds real value. At nume, every repeat order is clinically re-reviewed before dispatch. Pricing and what is included in a private prescription can be compared on the treatment options page.