There is considerable debate on if the placebo effect is real and for what situations it is. For example apparently it can cure a headache but AFAIK there is no

There is considerable debate on if the placebo effect is real and for what situations it is. For example apparently it can cure a headache but AFAIK there is no evidence it can cure actual physiological issues (cancer, sickness, ...) It makes some sense it would work on pain since pain at some point is just a signal to your brain and you chose consciously or unconsciously to change your perception of that signal. On the other hand there is nothing placebo will do to stop that cancer from growing or those viruses from multiplying.