What are the requirements for weight loss injections in the UK?

Does a high BMI alone mean you qualify?

This is probably the most common misconception we see, and it is worth correcting gently: a BMI of 30 or above puts you in the licensed range for these medicines, but it does not automatically qualify you. A prescriber looks at your complete medical history, existing conditions, any medicines you already take, contraindications listed in the product licence, and whether the treatment is appropriate given your individual circumstances.

The licensed thresholds per the UK product authorisations are a BMI of 30 or above for most adults, or 27 or above if you also live with at least one weight-related condition. Qualifying conditions at the lower threshold include type 2 diabetes, high blood pressure, raised cholesterol, obstructive sleep apnoea and cardiovascular disease. For some ethnic backgrounds (South Asian, Chinese, Middle Eastern, Black African or African-Caribbean) UK guidance applies BMI thresholds that are 2.5 kg/m² lower, recognising that health risks can emerge at lower weights in these groups. You can use the NHS BMI calculator as a starting point, though the prescriber's assessment goes considerably further than a single number.

Age matters too. These medicines are licensed for adults; neither Mounjaro nor Wegovy is suitable for anyone under 18. Pregnancy, breastfeeding, and actively trying to conceive are all situations where weight loss injections are not recommended, regardless of BMI.

What health conditions or history could affect your eligibility?

Certain medical histories require careful consideration before a prescriber can approve treatment. A personal or family history of medullary thyroid carcinoma, or of a condition called Multiple Endocrine Neoplasia type 2, is a contraindication for GLP-1 medicines. A history of pancreatitis also warrants careful prescriber discussion, the MHRA's Drug Safety Update programme has highlighted acute pancreatitis as a known, though infrequent, risk with GLP-1 medicines.

Kidney function, gallbladder history, and certain gastrointestinal conditions are also part of the picture. This is not a tick-box exercise. A thoughtful prescriber reads your answers and considers interaction with any other medicines you take. For instance, if you use oral contraceptives and are starting tirzepatide (Mounjaro), you will need to add a non-oral method of contraception for the first four weeks and after each dose increase, because the absorption of the pill may be reduced during that period, something the NHS England guidance on weight management injections sets out clearly.

People with thyroid conditions often ask whether they are excluded; the picture is nuanced and condition-specific. Our page on weight loss injections for thyroid patients covers this in more detail.

How do the NHS and private routes differ in their requirements?

The clinical eligibility criteria are set by the medicine's licence, those do not change depending on whether you access treatment through the NHS or a private pharmacy. What differs is the additional layer of requirements each route adds on top.

On the NHS, tirzepatide (Mounjaro) is currently commissioned for a narrower group: broadly, BMI 40 or above with four or more of a defined list of weight-related conditions, with further cohorts opening through 2026 and into 2027 as the phased rollout continues. Wegovy is available through specialist weight management services, typically with long waiting lists. Many people find they meet the licensed criteria but not the current NHS commissioning criteria, or simply cannot wait.

Through a regulated private pharmacy, the requirements return to the medicine's own licence: the BMI and health-condition thresholds above, plus a satisfactory clinical consultation. There is no referral and no waiting list, but the clinical gate is real, not a formality. If you are curious about what private treatment involves, our weight loss injection pricing page explains what an all-in private prescription typically covers. For a broader look at the treatment options available, the weight loss treatments overview is a useful reference.

Are the requirements different for men than for women?

The licensed eligibility criteria apply to all adults equally, the same BMI thresholds, the same contraindication list. In practice, though, men and women can experience these medicines somewhat differently. Men tend to carry more visceral fat and may see different metabolic responses; the side-effect profile is broadly similar but the experience of nausea, for example, can vary. Our dedicated page on weight loss injections for men explores the practical differences in more depth.

People with cardiovascular conditions sometimes wonder whether that history excludes them or in fact strengthens their case. The answer depends on the specific condition and its severity, a prescriber needs to weigh the risks and benefits individually. There is specific guidance on weight loss injections for people with heart conditions if that applies to you.

The short version: the requirements for weight loss injections are BMI-based thresholds, a qualifying health background where BMI falls in the 27–29.9 range, and a clinical consultation with a registered prescriber, and if you are specifically considering an injectable option you can read more about how the Mounjaro injection works for weight loss before that appointment. Everything else follows from that assessment.