Side Effect Placebo
The placebo effect is a powerful, robust, and poorly understood phenomenon in medicine. In fact it’s so ubiquitous that when researchers test drugs for their effectiveness, they have to go to great lengths to outsmart the placebo; employing so-called “double-blind” designs, so that even the experimenters don’t know which patients are getting which drug.
So it’s not that surprising that the lists of side effects that typically accompany modern medicines are themselves prone to placebo effect (which when applied to side effects is known as ‘nocebo’).
In one study, 50 patients with chronic back pain were randomly divided into two groups before a leg flexion test. One group was informed that the test could lead to a slight increase in pain, while the other group was instructed that the test would have no effect. Guess which group reported more pain and was able to perform significantly fewer leg flexions?
In other words, if you read the list of side effects, you’re more likely to experience the side effects. An interesting side point made in the article linked to above: This is a good reason to refrain from making comments to friends like “you look worn out,” as this can actually bring the feeling about, even if they weren’t feeling that way before.
So when it comes to medicine, maybe ignorance is bliss. Or if you prefer another old saw, don’t go investigating rare side effects too hard, because curiosity can, in fact, kill the cat.