3 links have been added on this idea.
  1. Some studies have proven that placebos can work even when patients are aware they are taking a placebo drug.

  2. Check out this story: A patient died from cardiac arrest after being given (unknowingly) a placebo instead of an adrenaline shot by paramedics. Such actions are unethical and borderline criminal!
    https://www.bbc.com/news/uk-wales-north-east-wales-43516136