Nocebo effect

A nocebo effect in medicine and veterinary medicine is called worsening of the symptoms or signs of a disease by the expectation, conscious or not, of the negative effects of a therapeutic measure. Arguably the opposite version of the placebo effect. It is a relevant concept in the specific fields of pharmacology, nosology and etiology. Nocebo is an adjective that is used to characterize a subject's harmful, unpleasant, and undesirable responses or reactions by administering a pharmacologically inert compound such that the subject's organic responses were not chemically generated (as a direct result of the action of the drug) but rather as a consequence of the subject's own pessimistic expectations in thinking that the drug would cause harmful, painful and unpleasant effects.

Therefore, in the nocebo there does not have to be a 'real' drug. But even so, the harmful and unpleasant consequences at the biochemical, physiological, emotional and cognitive level are. Like the placebo effect, it depends not only on rational expectations but on unconscious learning, which results from the experience of medical acts which is also applicable in the field of veterinary medicine.

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