WHO Guidance on Mounjaro and Wegovy: What It Means in the UK

What WHO decided, and when

The two announcements are often merged in headlines, so it helps to separate them.

• 5 September 2025, Essential Medicines List. The WHO Expert Committee added GLP-1 based medicines (semaglutide, dulaglutide, liraglutide and the dual agonist tirzepatide) to the Model List of Essential Medicines. The listing is for adults with type 2 diabetes who also have established cardiovascular disease, chronic kidney disease or obesity. The committee declined, as it had in 2023, to list them for obesity alone, and said high prices were limiting access.
• 1 December 2025, obesity guideline. WHO published its first guideline on GLP-1 therapies for the treatment of obesity in adults, alongside a summary in the Journal of the American Medical Association. It recognises obesity as a chronic, relapsing disease that needs lifelong care, and makes two conditional recommendations: that GLP-1 therapies may be used as long-term treatment, and that they should be combined with intensive behavioural support.

The original version of this page was written in September 2025, when the obesity guideline was still in draft. The final guideline followed the draft closely, and this page now reflects the published version.

What the obesity guideline actually says

The first recommendation reads, in plain terms: in adults living with obesity, GLP-1 receptor agonists or GIP/GLP-1 dual agonists may be used as long-term treatment for obesity. "Long-term" is defined as continuous treatment for at least six months, following the regulatory definition of chronic weight management. Pregnant women are excluded.

The evidence base was three sets of clinical trials, for liraglutide, semaglutide and tirzepatide, with treatment lasting from 26 weeks to over four years. The outcomes WHO weighed were weight change, quality of life, adverse events, major cardiovascular events and mortality. Certainty was moderate for follow-up under two years and lower beyond that, which is one reason the grade is conditional.

The second recommendation is that the medicines should be delivered with intensive behavioural therapy: structured goals for diet and physical activity, some form of energy restriction, regular counselling and routine progress checks. WHO also published good-practice statements on early diagnosis and person-centred, integrated care.

Who the guidance covers

WHO's recommendation applies to adults aged 19 and over with obesity, defined as a BMI of 30 kg/m² or higher. It deliberately does not extend to people with a BMI of 27 to 30 who have one or two weight-related conditions, because the trials that informed it enrolled mainly people at 30 and above and WHO wanted a global recommendation it could defend in every setting.

This is narrower than the UK position. The MHRA licences for Mounjaro and Wegovy allow prescribing at a BMI of 30, or from 27 with at least one weight-related condition such as high blood pressure, type 2 diabetes or sleep apnoea, with lower cut-offs for some ethnic backgrounds. Private pharmacies set their own joining and maintenance thresholds within that licence. Our BMI requirements guide lists what each pharmacy asks for. A separate WHO guideline for children and adolescents is in development.

The three medicines WHO assessed

• Tirzepatide (Mounjaro). A weekly injection that acts on two gut hormone receptors, GIP and GLP-1. The largest weight reductions in the trials WHO reviewed came from tirzepatide. Read what Mounjaro is and how it works.
• Semaglutide (Wegovy for weight, Ozempic for diabetes). A weekly GLP-1 receptor agonist injection, with an oral form for diabetes. In the UK, Wegovy prices are compared on our sister site iGovy.
• Liraglutide (Saxenda). A daily GLP-1 injection, the oldest of the three. Now available as a generic in the UK, which is part of why WHO listed it.

WHO chose not to rank the medicines. If you are deciding between them, our GLP-1 comparison sets out the trial results side by side.

Why "conditional" is not a hedge on effectiveness

In WHO's GRADE system a conditional recommendation means the panel is confident the benefits outweigh the harms for most people, but that the balance depends on circumstances. WHO gave four reasons for the grade, and none of them is doubt that the medicines produce weight loss: limited data on what happens after several years and after stopping, current prices, whether health systems can support continuous treatment with behavioural care, and the risk that access widens inequality between and within countries. The news release adds a warning about falsified GLP-1 products, which is why WHO ties supply to regulated prescribing.

The same four points explain why the Essential Medicines List still does not include obesity as a standalone indication. The Expert Committee has said that listing can be a catalyst for cheaper access, and that generic competition as patents begin to expire will matter more than any single decision.

What it means in the UK

On the NHS. Nothing changes automatically. NHS eligibility is set by NICE, which already recommends Wegovy through specialist weight-management services and tirzepatide through a phased roll-out that started in June 2025, prioritising people with the highest BMI and the most weight-related conditions. WHO's guideline supports the direction of travel but does not widen those criteria. Our NHS Mounjaro guide explains the current cohorts.

Paying privately. Private prescribing is governed by the MHRA licence and General Pharmaceutical Council rules, not by WHO. Prices are set by the manufacturers and by each pharmacy. The guidance has three practical implications for private patients:

• It reinforces that this is long-term treatment. If you are budgeting, plan for months and years rather than a short course. Our Mounjaro price comparison shows the cheapest total price at every dose, updated as pharmacies change them.
• The medicine works best with structured support on food and activity. Most UK online pharmacies offer some of this. The quality varies, so ask what is included before you pay.
• It reinforces the safety case for buying only from a regulated pharmacy. WHO's falsified-product warning applies as much to social media sellers in the UK as anywhere else. Every pharmacy on Monj is GPhC-registered and checked manually.

The bigger picture. A global recommendation from WHO that obesity is a chronic disease deserving structured medical treatment matters for the conversations people have with their GP, employer and family. It undercuts the idea that using these medicines is a shortcut, a theme we cover in our guide to weight-loss medication stigma, and it fits the evidence on health benefits beyond weight loss.

The barriers WHO named

• Cost. High list prices limit access in every country, including the UK, where most people on these medicines pay privately.
• Supply. Demand has outrun manufacturing before. The UK saw formal shortages of the higher Mounjaro doses in 2025.
• Health-system readiness. Continuous treatment with behavioural support needs staff, follow-up and monitoring that many systems do not yet have.
• Equity. WHO warned that low and middle-income countries risk being last in line, and committed to work during 2026 on a transparent framework for reaching people with the highest need first.