The placebo issue

Home > Research > Research information > The placebo issue

Topics covered on this page include:

  • Placebo effects in conventional medicine
  • Placebo effects in homeopathy

The ‘placebo effect’ can be described as a positive change seen after medical treatment which is caused solely by the patient’s psychological response to being given the treatment (improvement occurs because the patient expects to get better). Placebo effects are associated with all medical interventions. Placebo-controlled trials – which directly compare an experimental treatment with an inactive ‘dummy’ treatment – have therefore become a routine part of medical research in order to discover whether new treatments have any ‘real’ clinical effects above and beyond placebo.

Placebo effects in conventional medicine

Commentators frequently raise the subject of what role placebo plays in homeopathy, which can give a misleading impression that this issue is unique to homeopathy. In fact placebo has become a burning issue in the pharmaceutical industry in recent years, as an increasing number of initially promising new drugs have had to be abandoned during development because they are found to be no more effective than placebo.[1]

The level of placebo effect can be surprisingly high and even bring accepted treatments into question. A 2002 study found that a common knee surgery was no better than ‘fake’ placebo surgery.[2] These ‘arthroscopies’ are frequently used in the UK and the US e.g. for the treatment of arthritis, so such findings have enormous implications; in the U.S. more than 650,000 of these surgeries are performed annually at a cost of about $5,000 each.[3]

Placebo effects in homeopathy

Results from numerous high quality randomised controlled trials (RCTs) and several systematic reviews have shown that homeopathic medicines have a clinical effect above and beyond placebo (see Clinical trials for more information). Homeopathic treatment will also have a placebo effect, but this should not be confused with its indirect effects indirect effects such as the therapeutic effect of the homeopathic consultation.

Treatment by a homeopath gives patients the opportunity to explore their health problems thoroughly during one-to-one consultations with their practitioner. Some sceptics suggest that this process initiates a placebo effect responsible for much of the clinical results seen with homeopathic treatment, but a more accurate description would be that the homeopathic consultation has a ‘therapeutic effect’. If a patient treated by a psychologist improved, this would be correctly described as a therapeutic effect of the treatment not a placebo effect. The homeopathic consultation is clearly different from a psychotherapy consultation, but it does appear to have a strong therapeutic effect of great value to patients. A pragmatic trial is currently investigating the contribution the consultation process makes to the overall clinical effects of homeopathic treatment.(4). Lead investigator Dr Sarah Brien, Senior Research Fellow, The Complementary Medicine Research Unit, University of Southampton


1. Placebos Are Getting More Effective. Drugmakers Are Desperate to Know Why by Steve Silberman, 24 August 2009.

2. Moseley J, et al. A Controlled Trial of Arthroscopic Surgery for Osteoarthritis of the Knee. N Engl J Med, 2002; 347(2): 81-8, 132-3

3. Medscape, July 2002.

4. Lead investigator Dr Sarah Brien, Senior Research Fellow, The Complementary Medicine Research Unit, University of Southampton