Who Qualifies for Weight-Loss Injections in the UK?

If you're wondering about weight-loss injection eligibility in the UK, the short answer is that it hinges mostly on your Body Mass Index (BMI) and whether you have a weight-related health condition — but a prescriber always makes the final call. This guide sets out the actual thresholds used for Mounjaro (tirzepatide) and Wegovy (semaglutide), who tends to be turned down, and how NHS access differs from the private route.

Mounjaro and Wegovy are both prescription-only medicines. Nothing here is medical advice — it's plain-English information to help you understand whether you're likely to qualify before you apply. Every price quoted comes from our tracker of UK-regulated providers, last checked 25 August 2026.

Weight-loss injection eligibility in the UK: the BMI rules

The starting point is BMI, a rough measure of weight relative to height. For both Mounjaro and Wegovy, the standard private eligibility thresholds are:

• BMI 30 or above — you generally qualify on weight alone.
• BMI 27–29.9 — you may qualify if you also have a weight-related health condition.

Weight-related conditions that count include type 2 diabetes, high blood pressure (hypertension), high cholesterol, obstructive sleep apnoea, non-alcoholic fatty liver disease and heart disease. These lower the threshold because losing weight brings a clear medical benefit.

Mounjaro is MHRA-licensed for weight management and recommended by NICE (TA1026, December 2024). Wegovy has been available in the UK longer and carries the same broad BMI criteria.

Do the ethnicity adjustments apply?

Yes. For people from South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean backgrounds, prescribers often lower the thresholds by around 2.5 points — so roughly BMI 27.5+ (or 25+ with a condition) — because cardiometabolic risk rises at a lower BMI in these groups. Your prescriber will apply this during assessment.

Who usually doesn't qualify

Even if your BMI fits, a prescriber can decline you. Common reasons include:

• Pregnancy, trying to conceive, or breastfeeding — these medicines are not suitable.
• A personal or family history of medullary thyroid cancer, or the syndrome MEN 2.
• A history of pancreatitis, or active gallbladder disease.
• Certain eating disorders, such as active bulimia or binge-eating disorder that isn't being managed.
• Type 1 diabetes, or use of insulin/sulfonylureas without careful supervision (risk of low blood sugar).
• Being under 18 — most private services prescribe to adults only.

This is where an honest provider matters. Our recommended clinic, The Weight Clinic, refunds you in full if its prescriber decides the medicine isn't appropriate — so you're not out of pocket for applying honestly. No legitimate service should ever promise "guaranteed approval".

NHS versus private eligibility

The eligibility bar is very different depending on route.

On the NHS, Mounjaro is being rolled out in phases from 2025 through GP practices, prioritising people with the highest BMIs and the most weight-related conditions first. Access varies by area and waiting lists can be long. Wegovy on the NHS has generally been limited to specialist weight-management services, which also have strict entry criteria.

Privately, you complete an online consultation with a GPhC-registered pharmacy or CQC-regulated clinic. You'll be asked for your height and weight (sometimes a photo or video to confirm), your medical history and current medications. A prescriber reviews it before anything is dispensed. This is faster, but you pay the full cost yourself.

What it costs once you qualify

If you meet the criteria and choose the private route, price becomes the next question — and it varies a lot. The table below shows the cheapest starter-dose prices across the two main injections, plus our recommended provider, from our tracker.

Prices are per 4 weeks from our tracker of UK-regulated providers, last checked 25 August 2026. The Weight Clinic offers £35 off your first order with code NEWME. See the full price table for every provider and dose.

For Mounjaro alone the identical pen ranges from £131 to £220 a month — an £89 spread — so eligibility is only half the story. Where you fill the prescription changes what you pay for the same medicine. Our cost comparison breaks this down dose by dose.

How the assessment actually works

A typical private consultation takes a few minutes online. You'll confirm your BMI, disclose your medical history and any medicines, and answer questions designed to flag the exclusions above. If approved, you start on a low "starter" dose — 2.5 mg for Mounjaro or 0.25 mg for Wegovy — which is deliberately not a full treatment dose. It's stepped up slowly over the following months to limit side effects.

Good providers don't just post you a pen and disappear. The Weight Clinic runs monthly video reviews so a clinician can check your progress, adjust your dose and confirm it's still right for you. That ongoing oversight is part of safe prescribing, not an optional extra.

Which injection should you consider?

Eligibility is broadly the same for Mounjaro and Wegovy, so the choice often comes down to results, cost and how they fit your life. Mounjaro delivers larger average weight loss (around 21–22% at higher doses in SURMOUNT-1), while Wegovy has the longest UK track record and proven heart benefit. Our Mounjaro vs Wegovy comparison and our 5-question framework can help you weigh it up before you apply.

A note on safety and side effects

Common side effects across this class include nausea, diarrhoea, constipation, vomiting and tiredness. Rarer but serious risks include pancreatitis and gallstones. If you experience a side effect, you can report it through the MHRA Yellow Card scheme, which helps monitor medicine safety in the UK. Never buy these injections from unregulated sellers or "compounded" sources — only a GPhC-registered pharmacy or CQC-regulated clinic can prescribe and dispense them safely.

Frequently asked questions