adverse event

An adverse event (AE) is any adverse change in health or "side-effect" that occurs in a person who participates in a clinical trial while the patient is receiving the treatment (study medication, application of the study device, etc.) or within a pre-specified period of time after their treatment has been completed.
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Adverse event Malpractice An injury caused by medical management–rather than by the underlying disease–which prolongs hospitalization, [more]Adverse event - Community and Resources

In pharmacology, an adverse event is any unexpected or dangerous reaction to a drug.