Black Box Warning Law and Legal Definition

A black box warning is a warning that is seen on the package insert for prescription drugs that may cause serious adverse effects. A black border usually surrounds the text of the warning. It is also called a black label warning or boxed warning.

A black box warning indicates that medical studies show that the drug carries a considerable risk of serious or even life threatening adverse effects. The U.S. Food and Drug Administration may ask pharmaceutical companies to place a black box warning on the labeling of a prescription drug, or in literature describing it. It is the strongest warning that the FDA requires.