Adverse Drug Reactions: History, Terminology, Classification, Causality, Frequency, Preventability

No therapy that is effective is free of adverse effects. The detection of adverse effects of drugs and adverse reactions to drugs and other therapeutic interventions, the scientific basis of which has been delineated over the last 50 years, is more important than ever before, as therapy becomes increasingly complex and is used in increasingly ageing populations. Here I define pharmacovigilance, review its history, and discuss terminology and definitions in pharmacovigilance, medication errors, the pharmacological classification of adverse drug reactions, drug interactions, reporting suspected adverse drug reactions, causality assessment, frequencies of adverse drug reactions, risk perception and adverse drug reactions, class effects of drugs, unlicensed indications, off-label uses, and orphan drugs, preventing adverse drug reactions, and publishing accounts of adverse drug reactions. © 2012 John Wiley & Sons, Ltd.