The administration of a new drug to a patient because of side effects produced by another prescription. Later prescriptions increase the risk of further side effects, drug interactions, and patient harm. A prescribing cascade usually results from the failure of the health care prescriber to recognize a patient’s presenting illness as evidence of an adverse drug reaction. In many patients, but especially in those with diminished kidney or liver function, side effects of drugs are a common cause of drug toxicity and hospitalization.