From the late 1940s to 1991, the adverse effects of prescription drugs were primarily established through the publication of detailed case studies by doctors in medical journals. Subsequently, pharmaceutical companies would change the labels of medicines accordingly. This will be called “evident-based medicine” in this paper. After 1991, what is now called “evidence-based medicine” offers a markedly different view on establishing the adverse effects of a treatment, with randomised controlled trials (RCTs) held up as the gold standard. The differences between evidence- and evidence-based medicine are often framed in terms of the differences between specific and general causation. This article outlines the origins of these distinctions and the confusions they generate among both clinicians and the general public.