Thousands of patients in England are unable to access weight loss jabs via their GP, figures reveal, as doctors warn that the NHS rollout is “not fit for purpose”.

Family doctors got the green light to prescribe the drugs for the first time in June. About 220,000 people with “greatest need” were set to receive Mounjaro, also known as tirzepatide and made by Eli Lilly, on the NHS over the next three years.

But two months on, fewer than half (18 out of 42) of the commissioning bodies across England have confirmed they have begun prescribing the drug. Critics said the figures showed there was now a “postcode lottery” of access to weight loss jabs on the NHS.

NHS England had put in place a phased rollout of the drug over a period of up to 12 years, but the data suggests even patients who are eligible now cannot get the drug. Most patients on Mounjaro – about nine in 10 – are currently paying for it privately.

According to freedom of information requests made by the British Medical Journal (BMJ), few integrated care boards (ICBs) have been allocated enough NHS cash for patients eligible for weight loss drugs. Only nine had the funding needed to cover at least 70% of their eligible patients, the BMJ reported.

Ellen Welch, a co-chair of the Doctors’ Association UK, said: “These figures confirm the fear that the rollout is not fit for purpose. There is a huge discrepancy between national messaging and what patients are actually being delivered on a local level.”

Four ICBs told the BMJ the NHS funding they received covered just 25% or less of their eligible patients, with Coventry and Warwickshire faring the worst. That ICB said it had received funding to cover just 376 patients, despite identifying 1,795 eligible patients in the first year of rollout.

The rollout began on 23 June. Eligible patients in the first year include those with a body mass index (BMI) over 40 and other complicating illnesses such as high blood pressure, obstructive sleep apnoea, cardiovascular disease or type 2 diabetes.

Dr Jonathan Hazlehurst, a consultant endocrinologist and academic clinical lecturer at the University of Birmingham, said the rollout was “significantly underfunded”.

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“That clearly drives up distress and uncertainty both in patients and primary care and runs the risk of inequity in access to treatment, and that’s my biggest concern,” he said. “NHS England is talking about treating 220,000 patients in the first three years, but we can see that the initial funding for year one clearly only covers approximately 10% of that.”

Prof Nicola Heslehurst, the president of the Association for the Study of Obesity, said the figures showed there was a “postcode lottery” of access to obesity care.

The figures emerged just days after Wes Streeting pledged to do more to prevent people from being “priced out” of accessing weight loss jabs. The health secretary said he wanted more people to get them on the NHS after the manufacturer of Mounjaro said it was putting up prices in the private sector. Eli Lilly said in August that it was putting up the list price of the drug by as much as 170%.

NHS England said it was “fully supporting” the phased rollout of Mounjaro for eligible patients and had provided funding to commissioning bodies in March.

The Department of Health and Social Care said it expected commissioning bodies to be making the drug available as part of the phased rollout “so those with the highest need are able to access them”.