How could a sugar pill placebo cause harm? A new review of data from 250,726 trial participants has found that 1 in 20 people who took placebos in trials dropped out because of serious adverse events (side effects). Almost half of the participants reported less serious adverse events. The adverse events ranged from abdominal pain and anorexia to burning, chest pain, fatigue, and even death.
The study found that the apparently strange phenomena of sugar pills producing harm can be explained by misattribution and negative expectations.