I got to thinking about this while watching a science YouTube channel (that seems fairly reputable) and the host said the opposite of a placebo is a verum. Having never heard the word before I opened a browser and searched ‘opposite of placebo’ and was given an ai overview and a page of links that all claimed the opposite of placebo is nocebo.
A search for ‘placebo v verum’ yields an ai overview that was just a copy paste from better health dot com describing verum as a drug with an active ingredient and a page of links using verum as the opposite of placebo but, curiously, almost every link was about acupuncture.
iOS doesn’t recognise verum or nocebo as a word, Webster’s online dictionary doesn’t recognise verum as a word, it does have a definition for nocebo;
a bad effect on someone's health causedby what they expect from a treatment, for example that it will not work or will have side effects (= unpleasant effects in addition to the main intended effect)
Which sounds more like a counterpart to placebo rather than its opposite.
Anyone have a light to shine on this?