Editing Epiphenomenon (section)

===Medicine===
In the more general use of the word, a [[causality|causal relationship]] between the phenomena is implied;<ref name="MW_Collegiate" /><ref name="AHD" /> the epiphenomenon is a consequence of the primary phenomenon.<ref name="MW_Collegiate" /><ref name="AHD" /> This is the [[word sense|sense]] that is related to the noun ''[[epiphenomenalism]]''.

However, in medicine, this relationship is typically ''not'' implied, and the word is usually used in its second sense: an epiphenomenon may occur independently, and is called an epiphenomenon because it is not the primary phenomenon under study or because only [[correlation]], not [[causality|causation]], is known or suspected. In this sense, saying that X is [[association (statistics)|associated with]] Y as an epiphenomenon is preserving an acknowledgment that [[correlation does not imply causation]]. [[Medical sign|Signs]], [[symptom]]s, [[syndrome]]s (groups of symptoms), and [[Risk factor (epidemiology)|risk factor]]s can all be epiphenomena in this sense. For example, having an increased risk of breast cancer concurrent with taking an [[antibiotic]] is an epiphenomenon. It is not the antibiotic that is causing the increased risk, but the increased [[inflammation]] associated with the bacterial infection that prompted the taking of an antibiotic. The [[metaphor]] of a tree is one way of helping to explain the difference to someone struggling to understand. If the infection is the root of the tree, and the inflammation is the trunk, then the cancer and the antibiotic are two branches; the antibiotic is not the trunk.