: a harmless substance or treatment that when taken by or administered to a patient is associated with harmful side effects or worsening of symptoms due to negative expectations or the psychological condition of the patient

: a harmless substance or treatment that when taken by or administered to a patient is associated with harmful side effects or worsening of symptoms due to negative expectations or the psychological condition of the patient

: a harmless substance or treatment that when taken by or administered to a patient is associated with harmful side effects or worsening of symptoms 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.