On the NHS, weight loss injections are generally offered only to people with a higher BMI (often 35+ with a weight-related condition, and tighter still through specialist services), usually via a specialist weight management service or, more recently, through phased GP access for tirzepatide. The exact thresholds are stricter than many people expect, and demand far outstrips capacity — which is why access can be slow.
This guide explains the criteria the NHS uses, why they are set the way they are, and how the rules differ from a regulated private service. It is educational only — whether any treatment is right for you is a clinical decision made by a prescriber.
How NHS weight loss injection criteria work
The NHS does not simply offer weight loss injections to anyone who asks. Access is governed by NICE (the National Institute for Health and Care Excellence) guidance, by how each medicine is funded, and by local service capacity.
Two things matter most: your BMI (body mass index) and whether you have a weight-related health condition. The higher your BMI and the more serious any related condition, the more likely you are to meet the threshold.
Typical NHS BMI thresholds
Thresholds vary by medicine and by the route you access it through, but as a general picture:
- Historically, specialist NHS weight management services have used a BMI of around 35 or above with a weight-related condition (sometimes 30+ in specific circumstances).
- Lower thresholds may apply for certain ethnic groups, because weight-related health risks can occur at a lower BMI.
- Newer phased GP access routes have their own criteria that are being rolled out gradually and prioritise those with the highest clinical need first.
Because these thresholds and the rollout timetable change over time, the single most reliable step is to speak to your GP, who can tell you what is currently available in your area.
Why the NHS sets the bar high
Weight loss injections are effective but costly to provide at national scale, and the NHS must balance that against every other demand on its budget. NICE therefore targets funding at the people expected to gain the most clinical benefit — typically those with a higher BMI and existing weight-related illness.
There are also practical limits. Specialist weight management services have finite appointments, so waiting lists can be long. Being eligible on paper does not always mean fast access.
What counts as a weight-related condition?
A "weight-related comorbidity" is a health problem caused or worsened by excess weight. Common examples include:
- Type 2 diabetes
- High blood pressure (hypertension)
- Obstructive sleep apnoea
- High cholesterol or other cardiovascular risk factors
If you have one of these alongside a qualifying BMI, you are more likely to meet NHS criteria — but the final decision always rests with a clinician assessing your overall health.
Who is not suitable for weight loss injections
Regardless of how you access them, these medicines are not appropriate for everyone. Treatment is generally not suitable if you:
- Are pregnant, planning pregnancy or breastfeeding
- Have type 1 diabetes
- Have a personal or family history of medullary thyroid carcinoma or MEN2
- Have a history of pancreatitis or severe gastrointestinal disease
- Have an active eating disorder
- Have severe liver or kidney impairment
- Have a known allergy to the active ingredient
A prescriber will always review your full medical history before deciding whether any treatment is clinically appropriate.
NHS access vs a regulated private service
Many people who do not meet NHS thresholds, or who face long waiting times, consider a regulated private service instead. The core eligibility principles are similar, but the BMI thresholds for private treatment are often broader.
| Factor | NHS route | Regulated private service |
|---|---|---|
| Typical BMI threshold | Often 35+ with a condition (stricter via specialist services) | BMI 30+, or 27–30 with a weight-related condition |
| Age | 18+ | 18+ |
| Who prescribes | GP or specialist service clinician | GPhC-registered independent prescriber |
| Waiting times | Can be long due to demand | Usually faster after online consultation |
| Cost | Funded if eligible | Paid privately; prices from £115/month at The Weight Clinic |
At The Weight Clinic, private eligibility is: aged 18 or over, with a BMI of 30 or above, or a BMI of 27–30 alongside a weight-related condition such as type 2 diabetes, high blood pressure or sleep apnoea. A treatment is prescribed only if clinically appropriate after a free online consultation.
What treatments are available privately
If you are eligible privately, a prescriber may consider one of several MHRA-licensed options, depending on what suits you:
- Mounjaro (tirzepatide) — a weekly injection that activates two gut-hormone receptors, GLP-1 and GIP. In the SURMOUNT-1 trial, participants on the 15mg dose lost on average 22.5% of body weight over 72 weeks, alongside lifestyle support. Individual results vary; not everyone reaches this.
- Wegovy injection (semaglutide) — a weekly GLP-1 injection. In the STEP UP trial, adults on the 7.2mg dose lost on average 20.7% of their body weight over 72 weeks, alongside lifestyle support. Individual results vary; not everyone reaches this.
- Wegovy Tablet (oral semaglutide) — the same active medicine as the injection, taken as a once-daily tablet on an empty stomach. In the OASIS 4 trial, adults on 25mg lost on average 16.6% of their body weight over 64 weeks, alongside lifestyle support. Individual results vary; not everyone reaches this.
- Foundayo (orforglipron) — a small-molecule GLP-1 tablet taken once daily at any time of day, with or without food or water. In the Phase 3 ATTAIN-1 trial, participants on the 36mg dose lost on average 12.4% of their body weight over 72 weeks, alongside lifestyle counselling. Individual results vary; not everyone reaches this. (36mg is the trial capsule dose, which is above the maximum 17.2mg tablet strength supplied.)
You can compare these on our treatments overview and weight loss injections pages.
Side effects to be aware of
These medicines share a common side-effect profile. Common effects (affecting more than 1 in 10 people) include nausea, diarrhoea, constipation, vomiting, decreased appetite and fatigue.
Serious but rare effects include severe allergic reaction, acute pancreatitis, severe low blood sugar, severe gastrointestinal disease and worsening diabetic retinopathy. If you experience side effects, you can report them via the MHRA Yellow Card scheme at https://yellowcard.mhra.gov.uk/.
How to check your options
If you think you might meet NHS criteria, start by speaking to your GP about specialist weight management services in your area. If you do not meet the NHS threshold or face a long wait, a regulated private service may be an option.
However you proceed, choose a legitimate, GPhC-registered pharmacy. Our medicines are dispensed by our own GPhC-registered pharmacy (North Harrow Pharmacy, registration number 1034996), which you can verify on the General Pharmaceutical Council register. You can read more about us or get in touch via our contact page. To check whether treatment may be suitable for you, you can begin a free online consultation.
This article is for information only and is not a substitute for personalised medical advice. Weight-loss medicines are prescription-only, are not suitable for everyone, and are prescribed only after a clinical consultation with a GPhC-registered prescriber. Individual results vary. Always speak to a UK-registered pharmacist or doctor before starting or changing any prescription medication.
