An Unexpected Adverse Drug Reaction (UADR) is an adverse reaction suspected to be related to the investigational product and not consistent with the current reference safety information.
UADRs are important because unexpectedness may indicate emerging risk not previously characterized in development. These events are assessed for seriousness and reporting requirements, including whether they meet criteria for expedited reporting. Accurate UADR evaluation supports clear safety communications to sites and ethics committees. Strong documentation helps sponsors demonstrate effective pharmacovigilance and proactive risk management.