NHS spending on a blockbuster weight loss jab soared four-fold last year to over half a billion pounds with the bill now higher than any other drug.
Prescriptions for Mounjaro, which is also known as tirzepatide or the ‘King Kong’ of fat jabs, rose from 1.1million in 2024/25 to 3.1million in 2025/26.
It took the bill from £120million, when it was the tenth most expensive medicine in terms of overall spend, to £574million over the same period.
Taxpayers in England are now coughing-up almost twice as much for Mounjaro than they do for the second most-costly drug, a treatment for asthma and chronic obstructive pulmonary disease.
The figures, from the NHS Business Services Authority, cover drugs prescribed in the community outside of hospitals.
Experts last night expressed concerns about the ballooning bill, given access to fat jabs on the NHS is currently severely rationed and the government intends to make them available to millions more patients over the next few years.
Studies show Mounjaro, which is also used to treat type-2 diabetes, can boost users’ health and help them lose up to a fifth of their body weight in a little over a year.
The drugs watchdog NICE says around 3.4million obese people in England could benefit from treatment but NHS England has adopted a staggered rollout, with only around 220,000 of the fattest and sickest patients able to access the jabs in the first three years.
Prescriptions for Mounjaro, which is also known as tirzepatide or the ‘King Kong’ of fat jabs, rose from 1.1million in 2024/25 to 3.1million in 2025/26.
More than a quarter (28 per cent) of adults in England are obese and a further 36 per cent are overweight but rationing means most who want to use Mounjaro are forced to buy it privately.
Shimeon Lee, policy analyst at the TaxPayers’ Alliance, said: ‘Taxpayers will be seriously concerned that the NHS is already spending more than half a billion pounds a year on Mounjaro while ministers talk about making it available to millions more people.
‘These drugs may have clinical benefits, but the speed at which costs are ballooning shows just how quickly one treatment can pile on huge pressure.
‘Ministers need to be honest about the long-term costs, ensure prescribing is strictly targeted and avoid turning the NHS into an open-ended bill for lifestyle-related conditions.’
The Department of Health and Social Care announced in February that GPs will be paid millions of pounds in bonuses for prescribing Mounjaro to their fattest patients.
And former health secretary Wes Streeting has described weight loss jabs as a ‘real game-changer’.
But Professor Sir Chris Whitty, chief medical officer for England, has warned relying on weight-loss drugs to tackle the nation’s obesity crisis would be a ‘societal failure’ and said more must be done to prevent people getting fat in the first place.
Dr Marie Spreckley, an expert in weight management at the University of Cambridge, said: ‘The increase in prescribing and spending on tirzepatide reflects both the scale of obesity in the UK and the growing demand for treatments that can produce clinically meaningful weight loss.
The Department of Health and Social Care announced in February that GPs will be paid millions of pounds in bonuses for prescribing Mounjaro to their fattest patients.
‘For many patients, these medications can lead to substantial improvements in weight, metabolic health and quality of life.
‘However, the conversation should not focus solely on the cost of the medication itself.
‘The more important question is whether treatment is being delivered in a way that maximises long-term health outcomes and value for both patients and the NHS.
‘As access expands, it will be important to ensure that patients also receive appropriate nutritional, behavioural and clinical support alongside medication.
‘Weight loss alone does not necessarily equate to optimal health outcomes.
‘Appropriate support may help patients maintain adequate nutritional intake, preserve muscle mass and optimise longer-term health outcomes during weight loss.
‘From a public health perspective, the goal should be to ensure that effective obesity treatment is both accessible and delivered well.
‘The greatest return on investment will come not simply from prescribing medication, but from helping people achieve safe, sustainable and equitable health improvements over the long term.’
The number of prescription items dispensed outside of hospital in England hit a record 1.3 billion last year, a 3 per cent increase from 1.26 billion in 2024/25.
The cost of these prescribed items also hit an all-time high of £11.6 billion, a 4 per cent increase from £11.2 billion the previous year.
Atorvastatin, which is commonly used to lower cholesterol and prevent heart disease, was the most dispensed medicine in 2025/26, with 78 million items.
The NHS last year spent £285million on a combination of beclometasone dipropionate and formoterol, a therapy for asthma and chronic obstructive pulmonary disease, making it the second most costly medicine in terms of overall spend outside of hospitals.
An NHS spokesperson said: ‘Many of these prescriptions for tirzepatide were to treat diabetes rather than as weight loss drugs, with the period this data covers including NICE recommending expanded use of these drugs for adults with type 2 diabetes.
‘The NHS offers a wide range of support for obesity, helping tens of thousands of people achieve a healthier weight and wider lifestyle benefits – with the use of tirzepatide currently subject to strict eligibility criteria to prioritise those with the greatest clinical need.’
