It happens when people suffer side-effects because they expect to -- the opposite of the "placebo" effect when a patient gets better on a dummy drug they believe to be the real thing.
"Patients can experience very real pain as a result of the nocebo effect and the expectation that drugs will cause harm," said Peter Sever of Imperial College London, the lead author of a study published in The Lancet medical journal.
In this case, multiple reports of alleged side-effects from statins appear to have convinced people to experience them -- and prompted many to stop taking the drug.
A large-scale quitting of statins is estimated to have resulted in "thousands of fatal and disabling heart attacks and strokes, which would otherwise have been avoided," wrote the research team.
"Seldom in the history of modern therapeutics have the substantial proven benefits of a treatment been compromised to such an extent by serious misrepresentations of the evidence for its safety."
Statins are prescribed to lower cholesterol in people at high risk of heart attack or a stroke.
Known side effects include an increased diabetes risk, the study said. But muscle pain and weakness has remained contentious, with some studies finding a link, and others none.
The latest study offers an explanation for the apparent contradiction.
