London ? 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 condition.

And many doctors fail to make it clear these treatments don’t really do anything for the specific ailment for which they are prescribed, the survey found. That contradicts advice from the American Medical Association, which recommends doctors only 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 U.S. 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 edition 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. Studies have shown that patients given a fake or ineffective treatment can often improve, despite the pill having no known effect on their condition.

“It seems like doctors are doing things they shouldn’t be doing,” said Irving Kirsch, a professor of psychology at the University of Hull in Britain, who has studied the use of placebos.

“Doctors may be under a lot of pressure to help their patients, but this is not an acceptable shortcut,” he said.

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 which 62 percent believed that using placebo treatment was ethically acceptable.

Half of the doctors reported using placebos several times a month. Nearly 70 percent of those who did so described the treatment to their patients as “a potentially beneficial medicine not typically used for your condition.” Only 5 percent of doctors explicitly called it a placebo treatment.

Most doctors used actual medicines as a placebo treatment: 41 percent used painkillers, 38 percent used vitamins, 13 percent used antibiotics, 13 percent used sedatives, 3 percent used saline injections and 2 percent 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 percent said they would.

Smaller studies done elsewhere, including 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 believes 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 like pediatricians or surgeons.

Scientists still don’t understand how the placebo effect works – whether it is just psychological or whether there is also a physiological reaction.