Article Text

Download PDFPDF
Unethical informed consent caused by overlooking poorly measured nocebo effects
  1. Jeremy Howick
  1. Faculty of Philosophy, University of Oxford, Oxford OX2 6GG, UK
  1. Correspondence to Dr Jeremy Howick, Faculty of Philosophy, University of Oxford, Oxford OX2 6GG, UK; jeremy.howick{at}


Unlike its friendly cousin the placebo effect, the nocebo effect (the effect of expecting a negative outcome) has been almost ignored. Epistemic and ethical confusions related to its existence have gone all but unnoticed. Contrary to what is often asserted, adverse events following from taking placebo interventions are not necessarily nocebo effects; they could have arisen due to natural history. Meanwhile, ethical informed consent (in clinical trials and clinical practice) has centred almost exclusively on the need to inform patients about intervention risks with patients to preserve their autonomy. Researchers have failed to consider the harm caused by the way in which the information is conveyed. In this paper, I argue that the magnitude of nocebo effects must be measured using control groups consisting of untreated patients. And, because the nocebo effect can produce harm, the principle of non-maleficence must be taken into account alongside autonomy when obtaining (ethical) informed consent and communicating intervention risks with patients.

  • informed consent
  • autonomy
  • research ethics
  • epidemiology
  • ethics

Data availability statement

There are no data in this work.

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

Data availability statement

There are no data in this work.

View Full Text


  • Twitter @jeremyhowick

  • Correction notice This article has been updated since it was first published online. A number of typos have been updated.

  • Contributors JH is the sole contributor. He conceived of the idea, did the research and wrote the paper.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.