The power of the placebo is so incredible and interesting that I have shared many examples from this thought provoking book (Enjoy example #4):
Hippocrates’ Shadow: Secrets from the House of Medicine (David Newman)

“Moerman describes a study in which placebo injections for pain are given to two sets of patients under nearly identical circumstances. In the first, the physician is told that theres no chance that a real narcotic medication will be given. In the second, the physician is told that theres a chance that the patient will receive a narcotic. In both cases the patient receives a placebo, but the placebo is far more effective in relieving pain in the second case, when the physician believes that a narcotic may be in the injection. While the impact is very different in these cases, the only difference is in the physicians beliefs.”