Black Box Warning (Boxed Warning)

A black box warning, officially called a boxed warning, is the strongest safety warning the FDA requires on a prescription drug label. It appears in a black-bordered box at the top of the prescribing information and highlights a risk that can cause serious injury or death, or a step doctors must take to use the drug safely. Federal labeling rules at 21 CFR 201.57 set out where the box goes and require a concise summary of it in the label highlights.

Boxed warnings play a central role in drug litigation. Most drug injury lawsuits are "failure to warn" cases, which argue the manufacturer knew or should have known about a risk and did not tell doctors clearly enough. When the FDA later adds a boxed warning for that same risk, plaintiffs often point to it as evidence the danger was real, and they look at what the company knew before the change.

Boxed warnings can also be removed. The FDA added a boxed warning about leg and foot amputations to the diabetes drug canagliflozin (Invokana) on May 16, 2017, and removed it on August 26, 2020, after reviewing new clinical trial data. Chantix (varenicline) had its neuropsychiatric boxed warning removed in December 2016. A removal does not erase lawsuits over earlier use, but it can make causation harder to prove.

If you are researching a drug, check whether the label had a boxed warning when you started taking it and when you were injured. Our pages on the Ozempic lawsuit and Chantix lawsuit show how warnings factor into real cases.