An adverse event (AE) is any unintended change in health of a person who consumes or uses a medicine. Although the causality of the medicine and the adverse event cannot be determined, a researcher or healthcare practitioner must report all adverse events to the Food and Drug Administration (FDA)or the relevant regulatory authority in the country where the drug or device is to be registered. Fpr example in Malaysia, adverse drug reaction (ADR) must be reported to Malaysian Adverse Drug Reaction Committee (MADRAC).

"Serious" adverse events (for example life-threatening, illness requiring hospitalization & death) must be reported immediately!