The Nocebo Effect: When Words Make You Sick

An investigation of the nocebo effect—the placebo effect's evil twin.

Can beliefs make you sick? Consider "The June Bug" incident from a US textile factory in the early 1960s. Many employees began to feel dizzy, had an upset stomach, and vomited. Some were even hospitalized. The illness was attributed to a mysterious bug biting workers. However, when the CDC investigated this outbreak, no bugs or any other cause of the illnesses could be identified. Instead, it appears to be an illness caused by the mind — that is, sickness due to expectation.
The June Bug story is one of many striking examples of the nocebo effect, a phenomenon best summarized as the occurrence of a harmful event that stems from expecting it. The nocebo effect plays a role in side effects for some of the most commonly prescribed medications. It provides a lens for understanding how sensationalized media reports that sound alarm about public health might even become a...