A boxed warning is not “issued” by the FDA; it is merely required by the FDA. Specific wording or a template may be suggested by the FDA, but product labels and boxed warnings are written and issued by the manufacturer. This distinction may seem minor, but extensive litigation has occurred over whether manufacturers have met their duty to warn consumers about possible risks when using their products, and this duty cannot be shifted to the FDA.
A boxed warning may not be added to a product label at the option of a manufacturer. The FDA allows a boxed warning only if it requires the warning, to preserve its impact. It should be noted that some medical information sources (e.g., PDR.net) may include a “BOXED WARNING” in their drug monographs, but monographs not written by a manufacturer are not regulated by the FDA, and the text of their boxed warnings do not always correspond to the boxed warning that was approved by the FDA.
A boxed warning is not an indication that revocation of FDA approval is being considered or that it is likely to be revoked. FDA approval is subject to ongoing review and may be revoked at any time, without a prior boxed warning.
A boxed warning is not the highest level of warning. The FDA may require a manufacturer to send out a “Dear Health Care Provider” (DHCP) letter when an even higher or more urgent level of warning is deemed necessary. DHCP letters are usually accompanied by revisions of the product label, but most label revisions – and even most boxed warnings – are not accompanied by DHCP letters.
A boxed warning is not a statement about causation. Most warnings describe an “association” between a drug and an adverse effect, or “increased risk,” or instances of a particular adverse effect that “have been reported” in persons taking a drug. The words in a boxed warning are carefully chosen and require careful reading; in most cases they refrain from stating that a drug actually causes an adverse effect. The postmarketing surveillance data on which most warnings are based generally cannot provide the kind of evidence required to establish causation, and an association may be nothing more than an uncommon manifestation of the disorder for which the drug has been prescribed.
A boxed warning is not a statement about the probability of an adverse reaction occurring. The requirement for a boxed warning correlates better to the new recognition of a possible association than to the probability of an association. For example, penicillin has long been known to cause fatal anaphylaxis in 1/100,000 first-time administrations, but it does not have a boxed warning. The adverse consequences described in boxed warnings are often far less frequent – so much so that most physicians will never see them.
A boxed warning does not define the standard of care. The warning is a requirement imposed on the manufacturer, not on the practice of medicine. For legal purposes, the “standard of care” for the practice of medicine is defined state by state and is typically cast in terms such as “what most physicians would do in similar circumstances.” Physicians often prescribe drugs in spite of boxed warnings, just as they often prescribe drugs for “off label” indications, always balancing risk versus benefit.
A boxed warning does not constitute a contraindication to the use of a medication. Some warnings state that a drug is contraindicated in some situations, but product labels have another mandated section for listing contraindications, and most boxed warnings have no corresponding entry in that section.
A boxed warning does not necessarily constitute current information, nor is it always updated when new or contrary information becomes available. Revisions to boxed warnings, and to product labels in general, are made only after detailed review at the FDA, and the process of deciding whether an existing boxed warning continues to be appropriate may divert limited regulatory resources from more urgent priorities. Consequently, revisions to a boxed warning may lag behind the data that justify a revision by months or years. Revisions may never occur if softening or eliminating a boxed warning is deemed to be not worth the cost by a manufacturer.