Who meets the eligibility criteria for weight loss injections?

What the BMI thresholds actually mean in practice

The licensed starting point for both Mounjaro and Wegovy is a BMI of 30 or above. If your BMI sits between 27 and 29.9, you may still qualify, but only if you also have at least one weight-related condition such as high blood pressure, type 2 diabetes or prediabetes, high cholesterol, obstructive sleep apnoea, or osteoarthritis. The condition needs to be documented, not self-reported; a prescriber will want to see that it is genuinely present.

UK guidance also recognises that metabolic risk appears at lower BMIs in certain ethnic backgrounds. For people of South Asian, Chinese, Middle Eastern, Black African, or African-Caribbean heritage, the standard thresholds are typically reduced by 2.5 kg/m², so 27.5 rather than 30, for example. If that applies to you, it is worth flagging at consultation. You can run a quick sense-check using the NHS BMI calculator before you speak to a prescriber.

One thing our prescribers hear most weeks: people assume a BMI of 35 is required because that is the NHS commissioning threshold for funded treatment. It is not the licence threshold. The licensed eligibility criteria are broader (BMI 30 (or 27 with a comorbidity)) which is why private treatment routes exist for people who fall below the NHS-funded cutoffs. The full eligibility checker on this site walks through that distinction in detail.

Conditions that rule out these medicines, and some that need careful discussion

Certain personal or medical circumstances place weight loss injections outside what a prescriber can safely offer. Pregnancy, breastfeeding, and actively trying to conceive all sit in this category; these medicines are not recommended in any of those situations, and a prescriber will ask directly. Neither Mounjaro nor Wegovy is licensed for anyone under 18.

A personal or close family history of medullary thyroid carcinoma, or a condition called multiple endocrine neoplasia type 2, is a contraindication for both medicines. A history of pancreatitis, or certain gastrointestinal conditions, will prompt a prescriber to think carefully before prescribing, not necessarily a flat refusal, but a conversation that needs to happen. Kidney function, heart history, and current medicines (including some diabetes drugs) are also part of the picture.

If you are already on one of these treatments and thinking about switching provider, details about your current weight loss injection and dose history matter, a responsible prescriber will ask for evidence of where you are in the titration schedule before continuing or adjusting.

NHS eligibility versus private eligibility: two different sets of rules

This is where a lot of confusion is reasonable. NICE's appraisal of tirzepatide (TA1026) sets the criteria for NHS-funded Mounjaro: a BMI of 35 or above plus at least one qualifying comorbidity, delivered through a structured programme. Those criteria are considerably stricter than the medicine's licence, and the NHS is rolling out access in phases, not everyone who qualifies on paper has a practice or specialist service able to prescribe yet.

Private eligibility follows the licence, not the NICE commissioning threshold. That means the BMI floor is lower and the comorbidity requirement is more flexible, though a prescriber still applies clinical judgement to every case. If you are curious about what the NHS phased rollout covers and whether you might qualify that way, the weight management treatment overview sets that out clearly. For people who do not meet the NHS criteria, or prefer not to wait, a regulated private service is the practical alternative, provided the prescriber is satisfied the medicine is clinically appropriate for you specifically.

Understanding the cost landscape helps too. Private treatment pricing varies by dose and provider; the buying guide for weight loss injections explains what a legitimate private price should include and what to watch for.

What a clinical assessment actually involves

Because these are prescription-only medicines, the assessment is not a tick-box form. At nume, a GPhC-registered Independent Prescriber reads every consultation personally on the day it is submitted, your answers, your medical history, and your current situation. There is live weight verification by video and photo ID confirmation, so the prescriber is working with real data, not unverified self-report.

The questions cover your BMI, any weight-related health conditions, current medicines, contraindications, and what you are hoping to achieve, and if you are unsure where you stand before starting, the guidance on whether you would be eligible for weight loss injections is a useful reference to read beforehand. If you are transferring from another provider, evidence of your existing treatment is part of that review. Fertility considerations are also part of the picture for women of childbearing age; tirzepatide in particular requires an additional contraceptive method during the early stages of treatment and after each dose increase, because it can affect how oral contraceptives are absorbed. More on that is covered on the weight loss injections and fertility page.

The prescriber may approve treatment, ask a follow-up question, or decline if the clinical picture does not support it. That is the process working as it should. For a fuller look at how eligibility is assessed and what to bring to a consultation, the guide on meeting eligibility criteria is a practical next read.