In the United States, a boxed warning (sometimes 'black box warning', colloquially) is a type of warning that appears on the package insert for certain prescription drugs, so called because the U.S. Food and Drug Administration specifies that it is formatted with a 'box' or border around the text. The FDA can require a pharmaceutical company to place a boxed warning on the labeling of a prescription drug, or in literature describing it. It is the strongest warning that the FDA requires, and signifies that medical studies indicate that the drug carries a significant risk of serious or even life-threatening adverse effects.
Economists and physicians have thoroughly studied the effects of FDA boxed warnings on prescription patterns. It is not necessarily true that a physician and patient will have a conversation about a drug's boxed warning after it is issued. For instance, an FDA-mandated boxed warning decreased rosiglitazone use by 70%, but that still meant 3.8 million people were given the drug. Later research indicated that after receiving an FDA advisory, there was a decrease in rosiglitazone use, due to a combined effect of media exposure, advisory, and scientific publications, whereas pioglitazone (with a similar advisory) did not similarly decrease in use. This challenges the idea that physicians and patients will have a conversation after a boxed warning is issued. Throughout the country, boxed warnings will be translated into prescription patterns differently by different physicians.
In 2005, the FDA issued a boxed warning regarding the risk of atypical antipsychotics being prescribed among elderly patients with dementia. This advisory was associated with a decrease in use of antipsychotics, especially in elderly patients with dementia.
Boxed warnings on drugs have received increased media attention in the United States since 2004. Among some of the more widely covered stories:
In February 2006, the FDA's Drug Safety and Risk Management Advisory Committee voted to include boxed warnings on methylphenidate formulations used to treat attention deficit hyperactivity disorder, such as Ritalin (methylphenidate), due to possible cardiovascular side-effects. A month later, the agency's Pediatric Advisory Committee effectively rejected recommending boxed warnings for both cardiovascular and psychiatric adverse effects. (Minutes and transcripts of the relevant meetings are available on the FDA website.)
As of May 2013, the FDA has issued a black box warning regarding the use of thyroid hormone stimulating agents in treatment of obesity. Data does not indicate any benefits to using these agents for weight loss. Data does indicate an increased risk of life-threatening cardiovascular events when high levels of these agents are used in hypothyroid populations. Euthyroid populations demonstrate increased CV risk at clinical doses. Hypothyroid agents should not be used in combination with sympathomimetic agents including: stimulants, and diet pills, due to increased CV risks.
In July 2013, the FDA issued a boxed warning for the antimalarial drug mefloquine, noting the drug's adverse neuropsychiatric side effects, and emphasizing neurological effects from the drug could "occur at any time during drug use, and can last for months to years after the drug is stopped or can be permanent".
^"The heading and the summary must be contained within a box and bolded." 21CFR201.57 Subpart B (a)(4)