About half of American doctors in a new survey say they regularly give patients placebo treatments -- usually drugs or vitamins that won't really help their conditions.
And many of the doctors are not honest with their patients about what they are doing, the survey found.
That contradicts advice from the American Medical Assn., which recommends that doctors use treatments with the full knowledge of their patients.
"It's a disturbing finding," said Franklin G. Miller, director of the research ethics program at the National Institutes of Health and one of the study authors. "There is an element of deception here which is contrary to the principle of informed consent."
The study was being published online in today's issue of BMJ, formerly the British Medical Journal.
Placebos as defined in the survey went beyond the typical sugar pill commonly used in medical studies. A placebo was any treatment that wouldn't necessarily help the patient.
Scientists have long known of the "placebo effect," in which patients given a fake or ineffective treatment often improve anyway, simply because they expect to get better.
"Doctors may be under a lot of pressure to help their patients, but this is not an acceptable shortcut," said Irving Kirsch, a professor of psychology at the University of Hull in Britain who has studied the use of placebos.
Researchers at the NIH sent surveys to a random sample of 1,200 internists and rheumatologists -- doctors who treat arthritis and other joint problems. They received 679 responses. Of those doctors, 62% believed that using a placebo was ethically acceptable.
Half of the doctors reported using placebos several times a month, and nearly 70% of those described the treatment to their patients as "a potentially beneficial medicine not typically used for your condition." Only 5% of doctors explicitly called it a placebo treatment.
Most doctors used actual medicines as a placebo treatment: 41% used painkillers, 38% used vitamins, 13% used antibiotics, 13% used sedatives, 3% used saline injections and 2% used sugar pills.
In the survey, doctors were asked if they would recommend a sugar pill for patients with chronic pain if it had been shown to be more effective than no treatment. Nearly 60% said they would.
Smaller studies in Britain, Denmark and Sweden have found similar results.
Jon Tilburt, the lead author of the U.S. study, who is with NIH's bioethics department, said he thought the doctors surveyed were representative of internists and rheumatologists across the U.S. No statistical work was done to establish whether the survey results would apply to other medical specialists, such as pediatricians or surgeons.
The research was paid for by NIH's bioethics department and the National Center for Complementary and Alternative Medicine.
The authors said most doctors probably reasoned that doing something was better than doing nothing.
In some cases, placebos were given to patients with conditions such as chronic fatigue syndrome. Doctors also gave antibiotics to patients with viral bronchitis, knowing full well that a virus is impervious to antibiotics, which fight bacteria.
Some doctors think placebos are a good treatment in certain situations, as long as patients are told what they are being given. Dr. Walter Brown, a professor of psychiatry at Brown and Tufts universities, said people with insomnia, depression or high blood pressure often respond well to placebos.
"You could tell those patients that this is something that doesn't have any medicine in it but has been shown to work in people with your condition," he suggested.
But experts don't know if the placebo effect would be undermined if patients were explicitly told they were getting a dummy pill.
Brown said that although he hadn't prescribed sugar pills, he had given people with anxiety problems pills that had extremely low doses of medication.
"The dose was so low that whatever effect the patients were getting was probably a placebo effect," he said.
Kirsch, the psychologist, said it might be possible to get the psychological effect without using a fake pill. "If doctors just spent more time with their patients so they felt more reassured, that might help," he said.