+A **side effect** is an unintended consequence of an action or treatment. While often associated with [Medicine](/wiki/medicine) or drugs, it can arise in any complex system, revealing unforeseen impacts beyond the primary [Outcome](/wiki/outcome). These effects can range from minor to severe, altering the overall experience or efficacy.
+## See also
+- [Adverse Reaction](/wiki/adverse_reaction)
+- [Unintended Consequence](/wiki/unintended_consequence)
+- [Pharmacology](/wiki/pharmacology)