On a side note: if it’s a placebo and it works, it still works!
Yeah if someone’s benefitting from a placebo effect, the worst thing you can do is point out that it’s a placebo. If you convince them it won’t work, then you’ve just destroyed the therapeutic effect their brain was giving them. Just shut up and let the placebo do its thing.
Placebos work even when you knows it’s a placebo though. Pointing out something is a placebo is important because many are at best overpriced scams (homeopathy) and at worst actively harmful (chiropracty). The culture behind many placebos is also rife with pseudoscience and advocates against seeking out genuine care, so you should ensure nobody gets invested into placebos past a certain point.
One can make an informed decision regarding taking placebos if and only if one knows it’s a placebo, else one will be scammed and/or harmed.
Heroin is more an American traditional medicine since it gained the most popularity there (though it was invented in Germany),