Archive for August 14th, 2012

August 14, 2012


Subject-expectancy effect

In medicine, a nocebo [no-see-bo] reaction or response refers to harmful, unpleasant, or undesirable effects a subject manifests after receiving an inert dummy drug or placebo. Nocebo responses are not chemically generated and are due only to the subject’s pessimistic belief and expectation that the inert drug will produce negative consequences. In these cases, there is no ‘real’ drug involved, but the actual negative consequences of the administration of the inert drug, which may be physiological, behavioral, emotional, and/or cognitive, are nonetheless real.

An example of nocebo effect would be someone who dies of fright after being bitten by a non-venomous snake. The term ‘nocebo’ (Latin: ‘I will harm’) was chosen by Walter Kennedy, in 1961, to denote the counterpart of one of the more recent applications of the term placebo (Latin: ‘I will please’); namely, that of a placebo being a drug that produced a beneficial, healthy, pleasant, or desirable consequence in a subject, as a direct result of that subject’s beliefs and expectations. The term ‘nocebo’ can also refer to positive outcomes based upon the patient’s expectation of that outcome.

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