The thinking doctor’s guide to placebos

Discussion of the planned use on patients of the placebo effect is long overdue. For many years it has been medicine’s “dirty little secret.” Clinicians have found it to be an embarrassment that needs to be factored in when planning randomised controlled trials. Ethically its use has always been considered dubious. Recent high profile publications suggesting the lack of efficacy of selective serotonin reuptake inhibitors (SSRIs) in mild to moderate depressive illness have shown that clinicians routinely make use of the placebo effect—but from a position of ignorance rather than intention.1

Whatever one’s ethical stance, this state of affairs cannot be a good thing for our patients, our relationship with our patients, or the public purse. We outline a third way whereby clinicians can use the placebo knowingly yet still stay within the ethical constraints of modern medical practice.

Drugs given to conscious patients have at least three effects: one mediated through the biomedical activity of the drug; a nocebo effect2 (the opposite of placebo: negative non-biomedical effects); or a placebo effect.3 The placebo effect is usually expected to be synergistic with the biomedical effect and is often thought to be of less importance. Indeed a Cochrane review of placebo versus no treatment concluded: “There was no evidence that placebo interventions in general have clinically important effects. A possible small effect on continuous patient-reported outcomes, especially pain, could not be clearly distinguished from bias.”4 Other researchers have come to different conclusions: “The placebo effect appears in those instances where it is expected.”5 And others found neurobiological mechanisms of the placebo or nocebo effect.6 7

Hróbjartsson and Gøtzsche found that placebos are no panacea and do not work in all clinical conditions.4 This cannot imply that placebos should not be used, as interventions known …