Dr. Jeremy Howick of the University of Oxford in England and George Lewith of the University of Southampton said they found 97 percent of doctors have used "impure" placebo treatments -- such as non-essential physical examinations and blood tests performed to reassure patients -- while 12 percent used "pure" placebos -- such as sugar pills or saline injections which contain no active ingredients.
"The study shows that placebo use is widespread in Britain, and doctors clearly believe placebos can help patients," Howick said in a statement.
A random sample of doctors surveyed online -- representative of all British doctors registered with the General Medical Council -- indicated doctors prescribed placebos mainly to either induce psychological treatment effects, because patients requested treatment or to reassure patients.
Sixty-six percent of the doctors said pure placebos were ethically acceptable under certain circumstances and 33 percent said they were never acceptable. Impure placebos were more widely accepted, with 84 percent of doctors deeming them acceptable.
"This latest study demonstrates doctors are generally using placebos in good faith to help patients," Lewith said. "The placebo effect works by releasing our body's own natural painkillers into our nervous system. In my opinion the stigma attached to placebo use is irrational, and further investigation is needed to develop ethical, cost-effective placebos."
The results were published in the journal PLOS ONE.