Who Meets the Criteria for Weight Loss Injections in the UK

Step 1: Check whether your BMI meets the starting point

The first thing any prescriber looks at is body mass index. For both Mounjaro and Wegovy, the licensed threshold for weight management is a BMI of 30 or above. If your BMI sits between 27 and 29.9, you can still qualify provided you have at least one weight-related comorbidity — conditions that count include type 2 diabetes, hypertension, dyslipidaemia (high cholesterol or triglycerides), obstructive sleep apnoea and cardiovascular disease.

BMI thresholds are adjusted downward by 2.5 kg/m² for adults from South Asian, Chinese, Middle Eastern, Black African or African-Caribbean backgrounds, reflecting evidence that health risks from excess weight can appear at lower BMI values in these groups. So a BMI of 27.5 with a qualifying condition could bring someone in those groups into scope.

You can run a quick check using the NHS BMI calculator before booking anything — it takes under a minute and gives you a starting point for the conversation with a prescriber. Bear in mind a BMI figure alone never guarantees approval; it is the first filter, not the last.

The full overview of weight loss injections available in the UK explains how both medicines fit into the broader treatment landscape.

Step 2: Understand which medicine the criteria relate to

If you are weighing up your options, our guide to the 3 weight loss injections currently available sets out how tirzepatide, semaglutide and liraglutide compare. Their private-prescription eligibility criteria are broadly similar, but there are meaningful differences in how NICE recommends them for NHS use.

NICE recommends tirzepatide under technology appraisal TA1026 for adults with a BMI of 35 or above and at least one weight-related comorbidity, used alongside lifestyle support. For NHS tirzepatide access, the rollout is phased: from June 2025, those with a BMI of 40 or above and four or more qualifying conditions became eligible; from June 2026, the BMI threshold for that four-condition group dropped to 35. Further cohorts are expected from early 2027.

NICE recommends semaglutide (Wegovy) under TA875 for adults with a BMI of 35 or above and at least one comorbidity, but only within a specialist weight management service and for a maximum of two years. The BMI threshold can be 30–34.9 where specialist-referral criteria are met.

Private prescriptions follow the licensed product criteria rather than NICE's NHS-access restrictions, which is why private routes are accessible to a broader group. A prescriber on our clinical team reviews the full criteria for weight loss injections with you as part of the consultation.

Step 3: Know what the full clinical assessment covers

Meeting the BMI threshold is necessary but not sufficient. The prescriber also considers your medical history, current medications and any conditions that might affect safety. Certain situations require particular care: a personal or family history of medullary thyroid carcinoma, a history of pancreatitis, or certain gastrointestinal conditions are factors the prescriber weighs carefully.

Women of childbearing age are asked about contraception. For tirzepatide specifically, NHS guidance recommends adding a non-oral contraceptive method for the first four weeks of treatment and for four weeks after each dose increase, because the medicine can slow gastric emptying and temporarily reduce how reliably oral contraceptives are absorbed. You can read more about what GPs check before prescribing weight loss injections for context on what a thorough assessment involves.

A weight loss injection is not suitable during pregnancy, whilst breastfeeding, or for anyone trying to conceive, and these medicines are not licensed for under-18s. These are absolute exclusions, not points for negotiation with a prescriber.

The NHS England guidance on weight management injections sets out the safety considerations and wrap-around care expectations in detail.

Step 4: Decide between the NHS route and a private regulated pharmacy

If you meet NHS criteria, the GP or specialist route is worth pursuing, treatment is free at the point of care. The honest picture is that NHS access remains limited: eligibility is strict, phased and depends heavily on which conditions you have and how many. Waiting lists for specialist weight management services exist in most areas, and not all GP practices have opted into the new prescribing arrangement even where they could.

A private route through a regulated online pharmacy changes the timeline and the eligibility bar. There is no referral needed and no waiting list. The licensed eligibility criteria still apply and a prescriber still has to assess your full medical history, but the process moves quickly. If you are curious about what the private consultation actually involves, the treatment overview page walks through each stage.

For those comparing costs before starting, a look at what cheap weight loss injection listings often leave out is worth a few minutes of reading. Price is not the only variable; clinical oversight, supply chain legitimacy and aftercare support matter too.

If you think you meet the criteria and want a clinical view on whether treatment is appropriate for you, you can check your eligibility with our prescribers through a free consultation.