The Nocebo Effect, The Placebo Effect's Evil Twin
Nocebo is Latin for "I shall harm," whereas placebo means "I shall please." Those under the influence of the nocebo effect might experience painful symptoms just because they were informed that they might. However, the symptoms themselves are real—and even contagious. When the nocebo effect spreads across a large population, it can cause mass psychogenic illness. In this case, those who are reporting symptoms should be separated from those who aren't, and reassured that they will get better quickly.
from CGP Grey
Key Facts In This Video
Nocebos can cause harmful side effects because people think they're taking a real drug instead of an inert substitute, causing the body to react. (1:16)
The nocebo effect can spread from person to person in a mass psychogenic illness. (3:15)
Wind Farm Disease tends to occur in places where it's been mentioned on the local news, and not elsewhere. (5:05)