Understanding the “nocebo” effect, from the Harvard Mental Health Letter
Why do some people faint at the sight of a needle? Or start to sweat as soon as they walk into a dentist's office? The answer could be the nocebo effect.
The nocebo effect is the mirror image of the better-documented placebo effect. In Latin, nocebo means "I will harm," while placebo means "I will please." A placebo can enhance healing or pain relief, while a nocebo has the opposite effect — making people feel worse.