What BMI for Mounjaro? NHS and private requirements explained
Want to know if you're eligible to take Mounjaro? Discover the threshold BMI for Mounjaro in private and NHS settings.
Before starting Mounjaro (tirzepatide), you'll need to know if you're eligible for a prescription. The eligibility requirements are partly based on your body mass index (BMI).
BMI is a basic calculation that estimates body fat based on weight and height. It's not a perfect indicator of health, but it's still the main tool used to decide who can access GLP-1 weight loss treatments in the UK.
Not every health provider has the same Mounjaro BMI requirements. Here's how NHS and private providers compare.
NHS vs private BMI for Mounjaro: a side-by-side look
Mounjaro is available in the UK both on the NHS and through private providers (such as SemaPen). However, the BMI thresholds differ in each setting.
We'll look at these differences in detail below. But first, here's a simple breakdown:
| BMI Requirement | Weight-related health condition is required | Access pathway | |
|---|---|---|---|
| NHS¹ | At least 40 (or lower depending on ethnicity)* | Yes, 4 out of 5 from a list of weight-related health problems** | GP first, then referral to a specialist service |
| Private (e.g. SemaPen) | At least 30 (or 27 to 29.9 depending on ethnicity or with related health issue) | Yes (if BMI is 27 to 29.9) | Private medical assessment |
BMI for Mounjaro on the NHS: strict criteria and longer wait times
Mounjaro has been available through private providers in the UK since 2023. The NHS, meanwhile, started rolling it out to a small number of patients on 23 June 2025.
During this first phase of the rollout, you can only access Mounjaro if your GP refers you to a specialist weight management service.
To qualify, you generally need:
- A BMI of 40 or above (or lower depending on ethnic background)*
- Four out of five from a list of weight-related health conditions**
These rules have been designed so patients with the most urgent health needs can access Mounjaro first. The downside is that it can involve long waiting times, and only a limited number of people will meet the criteria.
To find out more,
see the official NHS guidance.
* Research shows that Black, Asian and other minority ethnic groups with a BMI of 23+ are at a higher risk of developing type 2 diabetes and chronic illnesses. Hence, a lower BMI cutoff is recommended.
** Type 2 diabetes, high blood pressure, cardiovascular disease, obstructive sleep apnoea and high cholesterol.
BMI for Mounjaro privately: faster access at a financial cost
Private providers generally allow more people to access Mounjaro.
They base their prescribing criteria on MHRA guidance, which allows people with a BMI of 30 or above to access Mounjaro. They also tend to take a more personalised and flexible approach to prescribing that's designed around your unique health profile.
You may be eligible to access Mounjaro privately if you meet the following criteria:
- You have a BMI of 30 or above.
- OR you have a BMI of 27 to 29.9, plus an obesity-related health issue like insulin resistance, prediabetes, high cholesterol or high blood pressure.
- OR you're a person of a certain ethnic background and have a BMI of 27 to 29.9.*
At SemaPen, we ask our patients to fill out a secure online health assessment. One of our experts will then review the assessment to see if Mounjaro is safe and appropriate for you to use. Part of this process involves checking for any health conditions or medications you're taking that could affect your treatment.
This means you don't need a referral from your GP, so the process tends to be quicker and easier. (You must, however, inform your GP that you're taking the treatment.)
SemaPen: more than just BMI checks
Do you want to lose weight safely with Mounjaro and keep it off? If you meet our Mounjaro BMI requirements, our team of obesity experts is here to help you:
- Find out if you're eligible quickly and easily online.
- Get reviewed by a UK specialist.
- Access the best weight loss programme for you, whether that's Mounjaro (tirzepatide), Wegovy (semaglutide) or the SemaHealth meal replacement programme.
As well as prescription medication, our specialist medical weight lossplans come with smart scales that send weight updates to our team. That means we can watch your progress with you, and step in to provide tailored support to help you stay on track.
Are you ready to see what specialist medical weight loss support can do for you? Take the next step on your weight loss journey today by completing our online health assessment. Our obesity experts will review your answers and recommend the best treatment for you.
Sources
1. NHS England (n.d.) Weight management injections. Retrieved from: https://www.england.nhs.uk/ourwork/prevention/obesity/medicines-for-obesity/weight-management-injections/
2. GOV.UK (2023) Press release: MHRA authorises diabetes drug Mounjaro (tirzepatide) for weight management and weight loss. Retrieved from https://www.gov.uk/government/news/mhra-authorises-diabetes-drug-mounjaro-tirzepatide-for-weight-management-and-weight-loss
This article was reviewed and approved by Lujain Alhassan, Bariatric Nutritionist, on 31 October 2025.
