Boxed Warning: What the Black Box on a Label Means
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Boxed warning

Also called black box warning, black-box warning · Reviewed

Definition: A boxed warning is a warning printed inside a border at the top of a US prescription drug label. FDA uses it for certain contraindications or serious risks, particularly those that may lead to death or serious injury. People often call it a black box warning.

What the rule says

Federal labeling rules (21 CFR 201.57) say FDA may require these warnings to be shown in a box. The box:

  • ordinarily must be based on data from people, but serious harm seen in animal studies can be enough when human data are missing;
  • must have a heading in capital letters that includes the word WARNING and says what the risk is about;
  • must briefly explain the risk and point to the numbered section of the label with the details.

Examples from current labels

Boxed warnings on three current US labels
ProductBox heading (short form)
Ozempic (semaglutide)Risk of thyroid C-cell tumors. Based on rodent studies; not known whether it happens in people.
Epogen (epoetin alfa)ESAs increase the risk of death, heart attack, stroke, blood clots and tumor growth or return.
Prolia (denosumab)Severe low blood calcium in people with advanced kidney disease.

The Ozempic box is an example of the animal-data route: the label says it is not known whether the drug causes these tumors in people. Many drugs have no box at all. The current Januvia, Jardiance and Xyosted labels do not have one.

Why it matters for your log

A box does not mean a drug is unsafe for everyone. It flags the risk FDA most wants prescribers and patients to weigh first. The Dose Track side-effect pages show the box, when there is one, above the trial numbers, so you can read it next to the rest of the label.

Read more on Dose Track: Ozempic side effects · Epogen side effects · Prolia side effects · Side effects from FDA labels

General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
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Frequently asked questions

Is a boxed warning the same as a black box warning?+
Yes. Black box warning is the everyday name. The federal labeling rule calls it a boxed warning.
Does a boxed warning mean I should stop my medicine?+
No. It flags a serious risk to weigh. Talk with your prescriber before stopping or changing any prescribed medicine.
Can a boxed warning be based on animal studies?+
Yes. The rule says it ordinarily rests on human data, but serious toxicity in animals can be the basis when human data are missing. The Ozempic thyroid tumor box is an example.

Sources

  1. 21 CFR 201.57: content and format of prescription drug labeling, Cornell LII
  2. Ozempic (semaglutide) US prescribing information, DailyMed
  3. Epogen (epoetin alfa) US prescribing information, DailyMed
  4. Prolia (denosumab) US prescribing information, DailyMed
  5. Januvia (sitagliptin) US prescribing information, DailyMed

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