> ## Documentation Index
> Fetch the complete documentation index at: https://glossary.micahealth.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Adverse event

An unwanted medical occurrence that happens to a participant during or shortly after a clinical study. This could be a new health problem or a worsening of an existing condition. While these health changes happen during the study, they may or may not be directly caused by the treatment being tested. Examples could include symptoms, abnormal test results, or new illnesses.

## Related terms

<CardGroup cols={3}>
  <Card title="Intervention/treatment" href="interventiontreatment" />
</CardGroup>

[*Source*](https://clinicaltrials.gov/study-basics/glossary)