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QuotationMarkLeft.png epithet given to any medicine adapted more to please than to benefit the patient QuotationMarkRight.pngQuincy's Lexicon-Medicum Revised by R Hooper. London 1812

Historically, a pill with no active ingredients. The concept is sometimes extended to include more sophisticated sham 'interventions'. Therapy given to conscious patients has the potential for at least four effects:

  1. Placebo effect
  2. Nocebo effect
  3. Beneficial biomedical effect
  4. Adverse biomedical effect


Placebo Effect

An observation that giving a placebo can produce reported improvements in symptoms despite the absence of active ingredients. Partly explained by the fact that many symptoms, for instance pain, are strongly modulated by psychological aspects so that fear and anxiety tend to accentuate pain.

Other similar effects include an observed efficacy of drugs depending on the colour.[1] Even the type of placebo can influence the size of the effect on the patient.[2]

The potential confounding effect of placebo treatments are well recognised. To counter this bias, research trials are ideally designed to be randomised, placebo-controlled, double-blind trials.[3]

QuotationMarkLeft.png The delivery of medical care is to do as much nothing as possible. QuotationMarkRight.pngSamuel Shem in the House of God'

QuotationMarkLeft.png The art of medicine consists in amusing the patient while nature cures the disease. QuotationMarkRight.pngVoltaire

Components of the Placebo Effect

It has been demonstrated that some of the factors contributing to the placebo effect can be separately analysed. This actually has produced results consistent with what is known of much of the art of medicine. Thus in one study the placebo of sham acupuncture produced a 16% improvement in adequate pain relief while the addition of a designed warmth, attention, and confidence building patient-practitioner relationship produced a further 18% gain [4].

Info bulb.pngThe correlation between bed side manner and placebo benefit might be postulated to help explain the known self selection process during medical training[5] as it is well known that specialities have a tendency to (self fulfilling) personality stereotypes[6]. Presumably an empathetic personality might be less necessary the stronger the evidence base for the biomedical components of usual therapy in a specialty. Thus areas of medicine with high cure rates might be attractive to personalities that found relying on empathy more challenging[7].

Size of placebo effect

The size of the placebo effect is related to the parameter evaluated. One early overview of 15 controlled trials suggested 35.2%[8]. In one study of the same stable asthmatics, that compared subjective improvement on visual analogue score, the improvement was 50% with salbutamol inhaler, 45% with placebo inhaler, 46% with sham acupuncture and 21% with no-intervention control (apart from interaction with study researchers). This study also showed that the objective measure FEV1 improved in 20.1% on the salbutamol but by only 7.3% in the other interventions[9].

See also


  1. de Craen AJ, Roos PJ, Leonard de Vries A, Kleijnen J. Effect of colour of drugs: systematic review of perceived effect of drugs and of their effectiveness. BMJ. 1996 Dec 21-28;313(7072):1624-6. (Direct link)
  2. Kaptchuk TJ, Stason WB, Davis RB, Legedza AR, Schnyer RN, Kerr CE, et al. Sham device v inert pill: randomised controlled trial of two placebo treatments. BMJ (Clinical research ed.) 2006;332:391-7. (Direct link – subscription may be required.)
  3. Kleijnen J, de Craen AJ, van Everdingen J, Krol L. Placebo effect in double-blind clinical trials: a review of interactions with medications. Lancet. 1994;344:1347-9.
  4. Kaptchuk TJ, Kelley JM, Conboy LA, Davis RB, Kerr CE, Jacobson EE, Kirsch I, Schyner RN, Nam BH, Nguyen LT, Park M, Rivers AL, McManus C, Kokkotou E, Drossman DA, Goldman P, Lembo AJ. Components of placebo effect: randomised controlled trial in patients with irritable bowel syndrome. BMJ (Clinical research ed.). 2008 Apr 3.(Epub ahead of print) (Link to article – subscription may be required.)
  5. Woolf J, McManus IC. Medical stereotypes and medical realities. British medical journal (Clinical research ed.). 1987 Jun 27; 294(6588):1660.
  6. Furnham AF. Medical students' beliefs about nine different specialties. British medical journal (Clinical research ed.). 1986 Dec 20-27; 293(6562):1607-10.
  7. Fennema K, Meyer DL, Owen N. Sex of physician: patients' preferences and stereotypes. The Journal of family practice. 1990 Apr; 30(4):441-6.
  8. BEECHER HK. The powerful placebo. Journal of the American Medical Association. 1955 Dec 24; 159(17):1602-6.
  9. Wechsler ME, Kelley JM, Boyd IO, Dutile S, Marigowda G, Kirsch I, Israel E, Kaptchuk TJ. Active albuterol or placebo, sham acupuncture, or no intervention in asthma. The New England journal of medicine. 2011 Jul 14; 365(2):119-26.(Link to article – subscription may be required.)
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