Black box warning
In the United States, a boxed warning (sometimes "black box warning", colloquially) is a warning that death or serious injury may result from the use of a particular drug. It appears near the beginning of the package insert for certain prescription drugs and biologics, so called because the U.S. Food and Drug Administration specifies that it be concise and be formatted with a "box" or border around the text and a heading in all caps, containing "WARNING", to emphasize its importance.