SUSAR
Suspected Unexpected Serious Adverse Reaction
What a definition is not
A definition is SPEQ’s plain-language decode of how a term is used in practice, cited to the documents that define it. It is a practitioner reference, not legal or regulatory advice, it does not replace the definition in the source, and where a regulator’s wording differs the regulator’s wording governs.
An adverse event that is serious, judged to have a reasonable possibility of a causal relationship to the investigational product, and not consistent with the reference safety information in the current Investigator’s Brochure or approved label. SUSARs trigger expedited regulatory reporting because they may signal a previously unrecognized safety risk.
The label applies only when all three criteria are met together: the event is serious, causality assessment finds a reasonable suspected relationship to the product, and the event is unexpected against the reference safety information — an expected, causally related serious event is not a SUSAR, and an unexpected but non-serious event is not either.
Fatal and life-threatening SUSARs carry a shorter expedited-reporting clock than other qualifying SUSARs, reflecting the greater urgency of communicating a signal that could be immediately life-threatening to other trial participants.
On confirmation, the sponsor notifies regulators, investigators, and the relevant ethics committees within the applicable timeline, and the event feeds into the ongoing benefit-risk assessment for the product, potentially triggering a protocol amendment or IB update.
- —Must meet three criteria together: serious, a reasonable suspected causal relationship, and unexpected against the current reference safety information.
- —Fatal or life-threatening SUSARs carry a shorter expedited-reporting clock than other SUSARs.
- —The Investigator’s Brochure, or approved label for marketed comparators, is the reference document used to judge unexpectedness.
- —Sponsors must notify regulators, investigators, and relevant ethics committees within the applicable expedited timeline.
ICH E2A Clinical Safety Data Management: Definitions and Standards for Expedited Reporting; 21 CFR 312.32 (IND Safety Reporting); EU Regulation 536/2014 (CTR), Article 42
Frequently asked questions
What does SUSAR stand for?
SUSAR stands for Suspected Unexpected Serious Adverse Reaction.
What is SUSAR?
An adverse event that is serious, judged to have a reasonable possibility of a causal relationship to the investigational product, and not consistent with the reference safety information in the current Investigator’s Brochure or approved label. SUSARs trigger expedited regulatory reporting because they may signal a previously unrecognized safety risk.
Which regulations cover SUSAR?
ICH E2A Clinical Safety Data Management: Definitions and Standards for Expedited Reporting; 21 CFR 312.32 (IND Safety Reporting); EU Regulation 536/2014 (CTR), Article 42