During the 1990's I was in a double blind study, the goal was to replicate a study conducted in Denmark (?) for Tamoxifen (a breast cancer drug), to study its preventative attributes (it does have them). I did not know if I was using the real thing or a placebo, no reactions. I was surprised when told I was on it, the staff administering the study thought it was hilarious that the placebo people noted more side effects. I think that when a drug makes it to the trials, much has been established for safety.