2. Adverse Event (AE) versus Adverse Reaction (adverse drug reaction ADR) – the distinction

Adverse Event (AE):

In the context of pharmacovigilance and outside a clinical trial: any untoward medical occurrence in a patient to whom a medicinal product is administered and which does not necessarily have a causal relationship with this treatment (based on ICH-E2D Guideline, see GVP Annex IV).

AEs can therefore be: any unfavourable and unintended sign (e.g., an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal product, whether or not considered related to this (see GVP Annex IV, ICH-E2D Guideline[1]).

In the context of a clinical trial: any untoward  medical occurrence in a participant to whom a medicinal product is administered and which does not necessarily have a causal relationship with this treatment [Reg (EU) No 536/2014 Art 2(2)(32)]. Adverse event is synonymous to adverse experience.

A participant means an individual who participates in a clinical trial, either as recipient of an investigational medicinal product or as a control [Reg (EU) No 536/2014 Art 2(2)(17)].