Referring specifically to homeopathy, the House of Commons of the United Kingdom Science and Technology Committee has stated:
In the Committee's view, homeopathy is a placebo treatment and the Government should have a policy on prescribing placebos. The Government is reluctant to address the appropriateness and ethics of prescribing placebos to patients, which usually relies on some degree of patient deception. Prescribing of placebos is not consistent with informed patient choice—which the Government claims is very important—as it means patients do not have all the information needed to make choice meaningful.
Beyond ethical issues and the integrity of the doctor-patient relationship, prescribing pure placebos is bad medicine. Their effect is unreliable and unpredictable and cannot form the sole basis of any treatment on the NHS.[21]
A survey in the United States of more than 10,000 physicians came to the result that while 24% of physicians would prescribe a treatment that is a placebo simply because the patient wanted treatment, 58% would not, and for the remaining 18%, it would depend on the circumstances.[101]
Changes over time[edit]
A review published in JAMA Psychiatry found that, in trials of anti psychotic medications, the change in response to receiving a placebo had increased significantly between 1960 and 2013. The review's authors identified several factors that could be responsible for this change, including inflation of baseline scores and enrollment of fewer severely ill patients.[102] Another analysis published in Pain in 2015 found that placebo responses had increased considerably in neuropathic pain clinical trials conducted in the United States from 1990 to 2013. The researchers suggested that this may be because such trials have "increased in study size and length" during this time period.[103]
Individual differences[edit]
Placebos do not work for everyone.[104][105] Henry K. Beecher, in a paper in 1955,[22] suggested placebo effects occurred in about 35% of people. However, this paper has been criticized for failing to distinguish the placebo effect from other factors, and for thereby encouraging an inflated notion of the placebo effect.[106]
In the 1950s, there was considerable research to find whether there was a specific personality to those that responded to placebos. The findings could not be replicated[107] and it is now thought to have no effect.[108]
The desire for relief from pain, "goal motivation", and how far pain is expected to be relieved increases placebo analgesia.[55] Another factor increasing the effectiveness of placebos is the degree to which a person attends to their symptoms, "somatic focus".[56] Individual variation in response to analgesic placebos has been linked to regional neurochemical differences in the internal affective state of the individuals experiencing pain.[109]
Those with Alzheimer's disease lose the capacity to be influenced by placebos, and this is attributed to the loss of their prefrontal cortex dependent capacity to have expectations.[110]
Children seem to have greater response than adults to placebos.[111]