Medical writers often have to write about or report medical errors, adverse events, and other not-so-nice parts of modern medicine. In my area of expertise, vaccine safety, we usually write about those rare serious adverse reactions after immunizations.
But this has to do with the inherent risk with all drugs (no drug is 100% safe). The story is different when the patient is harmed by a human error--like using the wrong medicine or an overdose. New research suggests that these errors are more common than usually thought.
There is a good review of the article here.