Suspected unexpected serious adverse reaction (SUSAR)

Any unfavourable occurrence in a trial participant that is judged to have a major impact on their health, was not anticipated and could potentially be due to the intervention under investigation.

SUSARs must be rapidly communicated to regulatory authorities. Trials may be suspended while a SUSAR is being investigated.

Safety monitoring and reporting for clinical trials in Europe (EMA, 2021)

Guidance for Industry and Investigators: Safety Reporting Requirements for INDs and BA/BE Studies (FDA, 2012)