Adverse Drug Reactions in the Elderly

An unexpected adverse reaction is a reaction whose nature or severity isn't consistent with the drug's current labeling.

A side effect is an unintended effect that occurs at normal drug dosages and relates to the drug's properties.

An adverse event or experience is a medical occurrence that may arise during treatment but doesn't have a causal relationship with the drug in question.

A serious adverse event is a fatal, life-threatening, or permanently disabling event that requires extensive hospitalization, leads to a congenital anomaly, or requires an intervention to avert permanent impairment or damage.

A signal is an observed possible adverse event that is unknown or wasn't previously documented.