In drug development, serious adverse event (SAE) is defined as any untoward medical occurrence during a human drug trial that at any dose
The term "life-threatening" in the definition of "serious" refers to an event in which the patient was at risk of death at the time of the event; it does not refer to an event which hypothetically might have caused death if it were more severe.[2] Adverse events are further defined as “Any untoward medical occurrence in a patient or clinical investigation subject administered a pharmaceutical product and which does not necessarily have to have a causal relationship with this treatment.”[2]