Serious adverse event
An adverse event meeting a formal severity threshold, such as requiring hospital admission.
Learning
What it means
A serious adverse event is one that meets defined criteria — for example, it results in death, is life-threatening, requires or prolongs hospital admission, causes lasting disability, or results in a birth defect.
Why it matters if you take part
"Serious" here is a regulatory classification, not a description of how bad someone felt. A very unpleasant symptom might not be classified as serious, while a precautionary overnight admission would be.
Related terms
This explains how clinical research works. It is not medical advice and does not describe any specific condition or treatment. Only a trial site can determine whether someone can take part in a study.