Definition of nocebo
: a harmless substance that when taken by a patient is associated with harmful effects due to negative expectations or the psychological condition of the patient
Did You Know?
Nocent has been in the English language as a word for "harmful" since the 15th century. It comes from Latin nocēre, meaning "to harm." Latin nocebo is a close relative that means "I will be harmful" and that contrasts with placebo, meaning "I shall please." People in medicine began using "placebo" for inert preparations prescribed solely for a patient's mental relief, and not for relieving a disorder, in the late 18th century. As doctors began to observe the effects of placebos, some noticed that the harmless preparations actually sometimes caused detrimental effects on the patient's health. English speakers began using the word nocebo for substances causing such adverse reactions in patients in 1961.
Origin of nocebo
Latin, I will be harmful; after placebo
First Known Use: 1961
Medical Definition of nocebo
: a harmless substance or treatment that when taken by or administered to a patient is associated with undesirable or harmful side effects or worsening of symptoms due to negative expectations or the psychological condition of the patient
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Medical Dictionary: Definition of "nocebo"
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