Here is a wide-ranging article about proposals to utilize placebos as medicine.

But according to advocates, there’s enough data for doctors to start thinking of the placebo effect not as the opposite of medicine, but as a tool they can use in an evidence-based, conscientious manner. Broadly speaking, it seems sensible to make every effort to enlist the body’s own ability to heal itself–which is what, at bottom, placebos seem to do. And as researchers examine it more closely, the placebo is having another effect as well: it is revealing a great deal about the subtle and unexpected influences that medical care, as opposed to the medicine itself, has on patients.

The article never mentions it so I wonder if any consideration has been given to the equilibrium effects.  Presumably the placebo effect requires the patient to believe that the drug is real. Then widespread use of true placebos will dilute the placebo effect.  Since real drugs also contribute a placebo effect on top of any pharmacological effects, the placebo component of existing drugs will be reduced.

Does the benefit of using placebos outweigh the cost of reducing the effectiveness of non-placebos?  If there is a complementarity between the placebo effect and real pharmacological effects it could be that zero is the optimal ratio of placebo to non-placebo treatments.

Note to my behavioral economics class:  this is a good example of a topic that would require the tools of psychological game theory due to the direct payoff consequences of beliefs.