The #nocebo effect is a rather mysterious set of reactions to diagnoses, medications or procedures spawned by negative thoughts, often rooted in fear or #anxiety, which then manifest in unwanted physical symptoms.
Though not completely understood, research on people getting #covid #vaccines has added to other studies helping scientists explain how this rough inverse of the #placebo effect works, and the negative outcomes it can generate.
https://medium.com/wise-well/the-incredible-harmful-power-of-negative-thinking-7d0a64943b09