In many medical studies, even people who take "fake" treatments, such as sugar pills with no active ingredients, can still feel better. These are the puzzling "placebo effects". They are common, diverse and powerful and they raise an interesting ethical question – can doctors justifiably prescribe placebos to their patients? The standard answer is no.
But many of the arguments are based on the idea that placebo effects depend on belief; people must expect that treatments will work in order to experience any benefits. For a doctor to prescribe a placebo, they'd need to deceive. But according to Ted Kaptchuk from Harvard Medical School, deception may not be necessary. In a clinical trial, he found that patients with irritable bowel syndrome (IBS) felt that their symptoms improved when they took placebo pills, even if they were told that the pills were inactive.