Yes, this idea comes around once in a while This has been covered in some detail on the Science-Based Medicine Blog (e.g. HERE). There are several problems with the notion that therapies without any real biological effects “work” via the placebo effect.
1. Placebo effects don’t lead to meaningful changes in objective outcomes of disease, things like mortality and survival, tumor growth, lung function, lab tests, and such. They tend to affect subjective symptoms, like pain, nausea, etc. In other words, placebo effects generally don’t change your disease or your physical health, they just change your perception of your condition. This might have some limited value in reducing discomfort, but as I’ll point out in a minute, there are better ways with less risk to get this effect.
A nice illustration of this problem was a study that compared acupuncture and a placebo inhaler to real medicine for asthmatics. The acupuncture and inhaler made the subjects feel like they could breath more easily. But only the real medicine actually changed objective measures of lung function. This means that if these patients were consistently treated with the placebo therapies, they would feel better but their lungs would not be treated and would continue to get worse. So fooling the brain into thinking the body is better when it isn’t is dangerous.
2. Placebo effects aren’t very strong in most cases. They consistently have much lower impact even on subjective symptoms than real medicine, which is how we tell when a medicine really works in a clinical study-by showing that it has more effect than a placebo used for comparison. SO again, substituting placebos for real therapies leaves patients with less relief, and no real change in their condition, compared with a truly effective medicine.
3. Placebo effects are just as strong for real medicines as for treatments that don’t work. So giving someone a placebo pill gives them a small amount of perceived improvement. Giving someone a pill that really works gives them the same perceived improvement on top of real improvement.
4. Placebo effects generally don’t happen if you honestly tell people the therapy is a fake. So the only way to get these benefits without giving a real therapy is to lie to people about the fake therapy, which raises serious ethical questions.
Finally, there is often some confusion about what “placebo effect” really means. Some of the effect measured in research studies is the result of belief and expectation on the part of subjects getting an inert therapy, which is what most people think of when they use the term. But a chunk of the effect seen in placebo groups is due to other things, including the better care and monitoring subjects get when included in a clinical trial, the better adherence to existing treatments, and so on. These factors give an appearance of improvement on placebo treatment in research studies, but they wouldn’t not be part of any placebo effect for non-research subjects taking a fake therapy marketed as real medicine, like homeopathy.
So while there are some interesting changes in brain chemistry, pain perception, and autonomic function brought about by the belief one is getting a real medical treatment, these don’t really serve as justification for giving people fake therapies that only have effects generated by the mistaken belief they are real medicine.