Almost all doctors have prescribed placebos to patients at least once in their career, according to a survey by Southampton researchers.

The poll of doctors working in the UK, which was put together by the University of Southampton, found that 97 per cent had used unproven treatments or carried out non-essential physical examinations and blood tests.

The sample of almost 800 doctors found that placebos were mainly given to either induce psychological treatment effects because patients requested treatment, or to reassure patients that they were healthy.

The research, which was carried out jointly with representatives from Oxford University, was funded by the National Institute for Health Research, the University of Oxford Department of Primary Health Care Sciences and The Southampton Complementary Medical Research Trust.

Professor George Lewith, co-lead author of the study from the University of Southampton, said: “This latest study with the University of Oxford demonstrates that doctors are generally using placebos in good faith to help patients.

“Other previous published studies by Southampton have clearly shown placebos can help many people and can be effective for a long time after administration.”