Doctors are to stop giving patients scores of tests and treatments, such as x-rays for back pain and antibiotics for flu, in an unprecedented crackdown on the “over-medicalisation” of illness.

In a move that has roused fears that it will lead to the widespread rationing of NHS care, the body representing the UK’s 250,000 doctors is seeking to ensure that patients no longer undergo treatment that is unlikely to work, may harm them and wastes valuable resources.

The Academy of Medical Royal Colleges wants to bring an end to a culture of “too much medicine” in which “more is better” and doctors feel compelled to always “do something”, often because they feel under pressure from the patient, even though they know that the treatment recommended will probably not work.

Many patients with asthma, prostate and thyroid cancers, and chronic kidney disease already undergo “unnecessary care” because they are “over-diagnosed” and thus “over-treated”, the academy claims.

In a major change to patients’ relationships with their doctors, it will try and persuade the sick to stop expecting to automatically receive some form of medical intervention, such as drugs or surgery.

In future, doing nothing for the patient may be the best thing to do for them, according to the academy.

It wants doctors to start talking honestly to patients about the benefit or potential lack of benefit from a certain procedure and the possibility that some treatments can involve risk, and about alternative ways of handling their illness.

In an article in the BMJ, a group of senior doctors – including the academy president, Prof Dame Sue Bailey, and her predecessor Prof Terence Stephenson – say: “These new conversations will rebalance discussions about the risks and benefits of tests and interventions, such that doctors and patients will be supported to acknowledge that a minor potential benefit may not outweigh potential harm, the minimal evidence base, and substantial financial expense and therefore that, sometimes, doing nothing might be the favourable option.”

Patients’ desire for treatment “has bred unbalanced decision-making. This has resulted in patients sometimes being offered treatments that have only minor benefit and minimal evidence, despite the potential for substantial harm and expense”, write the doctors.

They warn that the NHS will not be able to cope with growing demand for healthcare unless over-treatment is banished. “This culture threatens the sustainability of high-quality healthcare,” they add.

The NHS’s “tariff” system of paying hospitals for treatment incentivises them to undertake medical activity, as does the Quality Outcomes Framework system under which GPs are rewarded for, for example, treating high cholesterol or high blood pressure, they say.

“Defensive medicine, patient pressures, biased reporting in medical journals and a lack of understanding of health statistics and risk” have also contributed to some treatments being performed regularly, despite a lack of robust evidence showing they work, they add.

The academy – whose 21-member medical royal colleges represent different types of doctors such as GP, surgeons and hospital physicians – has decided to introduce a policy called Choosing Wisely, which is already used in the US, Australia, Germany and other countries. It aims to get doctors to “stop using various interventions that are not supported by evidence, free from harm, and truly necessary”.

By the autumn each of the medical royal colleges will have drawn up a list of the top five tests or procedures their members do which are of “questionable value”, giving a final list of about 100 interventions, and advise doctors to stop using them.

The Patients Association criticised the plan. “For me, the concern is that I hope this is not the start of the road to widespread rationing of investigations and treatments, but I fear it might be,” said Katherine Murphy, its chief executive, who is a former NHS manager and former nurse.

“We acknowledge that the NHS has to balance the books, but that should not be at the expense of treating patients appropriately. While not treating a cold or flu might be the best thing to do, I would be very concerned that [in future] a GP or hospital doctor might think twice about whether ordering an investigation for the patient to get a diagnosis, such as a scan or x-ray, is needed or not,” she added.

But Bailey said: “The whole point of Choosing Wisely is to encourage doctors to have conversations with their patients and about the value of a treatment. It’s not, and never will be, about refusing treatment or in any way jeopardising safety. It’s just about taking a grown-up approach to healthcare and being good stewards of the resources we have.”

Dr Aseem Malhotra, a cardiologist and the academy’s consultant clinical associate, said: “We have unwittingly been complicit in creating an epidemic of misinformed doctors and misinformed patients contributing to considerable harm and great expense to our health systems and national economies.”

Prof Maureen Baker, chair of the Royal College of GPs, said: “If there is evidence to show that a particular intervention might be of little benefit to a patient, it is good practice that alternatives are explored. For example, mindfulness and talking therapies have been shown to have positive effects in some patients with recurring depression and anxiety, as opposed to taking antidepressants.

“However, family doctors are often under considerable pressure to prescribe, or take some form of action, as a result of a patient consultation, so it is important that we work together to make people realise that drug or surgical treatment isn’t always the best way forward.”

An NHS England spokesman said: “NHS England has been working as a partner with the Academy of Royal Medical Colleges to join the international campaign of Choosing Wisely to establish which interventions do not help patients in the care of their condition.

“There is much evidence that there is significant overuse of some treatments such as antibiotics but when medicines are needed it’s important that patients receive them.”

The Department of Health did not respond to requests for comment.