How FDA decides between a boxed warning, a Warnings and Precautions entry, a contraindication or a REMS, using the GLP-1 eye warning and TGCT drugs as examples.
Last updated: November 11, 2026
A boxed warning is the FDA’s strongest label alert, used when a risk is serious relative to benefit, can be reduced by careful use, or the drug comes with use restrictions. Warnings and Precautions covers serious or clinically significant risks with reasonable evidence of a causal link.
Scope: the four main places risk shows up on a US prescription drug label, the evidence thresholds FDA applies, how labels change after approval, and what each level means commercially.
Why does this matter this week?
Two FDA actions in three days show the ladder in practice. On November 9, 2026 the FDA required every GLP-1 receptor agonist to add a potential risk of a rare optic nerve condition, NAION, to the Warnings and Precautions section, not a boxed warning. On November 10 it approved Pimjetmi (pimicotinib) for tenosynovial giant cell tumor with a hepatotoxicity warning and no boxed warning mentioned in the approval notice, while the first drug in that class, Turalio, was approved in 2019 with a boxed warning and a REMS. Same organ, liver, very different label weight.
What is a boxed warning?
A boxed warning is a brief, bold summary of a serious risk placed in a box at the top of the prescribing information. FDA’s final guidance on these label sections (October 2011) says it should be a concise summary in bold, bulleted or similar format, with the full detail cross referenced to other parts of the label.
The guidance lists three situations that call for one:
- An adverse reaction so serious in proportion to the potential benefit (for example fatal, life threatening or permanently disabling) that it must be weighed before prescribing.
- A serious adverse reaction that can be prevented or made less frequent or severe by appropriate use, such as patient selection or careful monitoring.
- The drug was approved with restrictions to ensure safe use, meaning a REMS with elements to assure safe use.
The guidance notes boxed warnings are most likely to rest on observed serious adverse reactions, and can occasionally flag other critical information, such as reduced effectiveness in certain patients.
What goes in Warnings and Precautions?
Warnings and Precautions is the label’s main list of serious or otherwise clinically significant risks. FDA’s threshold is “reasonable evidence of a causal association” between the drug and the event; a causal relationship does not need to be definitively established. That is a lower bar than people often assume.
“Otherwise clinically significant” covers reactions that could lead to a serious outcome, carry a high absolute risk, or affect whether patients keep taking the drug. The guidance also says terms like “Do not use” do not belong in this section, because they imply a contraindication.
When is a drug contraindicated?
A contraindication is reserved for situations where the risk clearly outweighs any possible therapeutic benefit. Per the 2011 guidance, only known hazards, not theoretical possibilities, can be the basis for one, and if there are none the section must say “None.” The preferred wording is “is contraindicated in,” not “should not be used.”
What is a REMS and how does it relate to a boxed warning?
A Risk Evaluation and Mitigation Strategy (REMS) is a drug safety program the FDA can require for certain medicines with serious safety concerns, to help make sure benefits outweigh risks. FDA says only a few medicines need one. A REMS with elements to assure safe use, such as prescriber certification or monitoring before dispensing, is one of the three triggers for a boxed warning in FDA’s guidance.
Turalio (pexidartinib) is the textbook case: FDA approved it in August 2019 with a boxed warning for serious and potentially fatal liver injury, and only through a REMS program, with liver tests weekly for the first eight weeks.
The four levels side by side
| Label tool | FDA threshold (2011 guidance and REMS page) | Recent example | Commercial weight |
|---|---|---|---|
| Contraindication | Risk clearly outweighs any possible benefit; known hazards only | Population specific bans in many labels | Removes a patient group entirely |
| Boxed warning | Serious risk relative to benefit, preventable with careful use, or restricted distribution | Injectafer low phosphate risk (added Sept 2026, per FDA’s safety communications list) | Highest; shapes formulary review, promotion and prescriber caution |
| REMS | Required for certain drugs with serious safety concerns | Turalio liver monitoring program (2019) | Adds operating cost and access friction |
| Warnings and Precautions | Serious or clinically significant; reasonable evidence of causal association | NAION class warning for all GLP-1 RAs (Nov 9, 2026); Pimjetmi hepatotoxicity (Nov 10, 2026) | Usually modest; can still change monitoring and counseling |
Table: BioMed Nexus framework built from FDA’s 2011 labeling guidance, FDA’s REMS page and FDA safety communications.
What did FDA actually require for GLP-1 drugs?
FDA’s November 9, 2026 Drug Safety Communication requires holders of all GLP-1 RA applications to add information on a potential increased risk of non arteritic anterior ischemic optic neuropathy (NAION) to Warnings and Precautions. FDA’s product table lists 12 trade names, with Byetta footnoted as voluntarily withdrawn.
The evidence shows why this landed in Warnings and Precautions rather than a box. An FDA meta analysis of 126 trials and 134,253 patients found 15 probable NAION events, 10 on GLP-1 RAs and 5 on placebo: 6.4 versus 3.8 events per 100,000 patient years. In FDA’s Sentinel data, the hazard ratio was 1.43 (95% CI 1.02 to 2.01) against DPP-4 inhibitors but 1.19 (0.91 to 1.54), not significant, against SGLT-2 inhibitors. That is reasonable evidence of an association, which meets the Warnings and Precautions bar, with a very low absolute rate.
FDA’s advice: patients should contact a clinician right away for sudden, painless vision loss in one eye; clinicians should refer suspected cases promptly to an ophthalmologist and consider stopping the drug in patients who develop NAION unless the benefits clearly outweigh the risk.
How do labels change after approval?
Labels move both ways. Section 505(o)(4) of the Federal Food, Drug, and Cosmetic Act lets FDA require application holders to make safety labeling changes based on new safety information that becomes available after approval. It covers NDA drugs, BLA biologics and some ANDA generics when the reference drug is no longer marketed.
FDA’s September 2025 draft guidance, which would replace the 2013 version once final, lays out the clock:
- The holder must submit a labeling supplement or a rebuttal within 30 days of FDA’s notification.
- Any discussion period lasts no more than 30 days unless extended.
- FDA can then issue an order within 15 days, and the holder must file within 15 days of the order or appeal within 5 days.
- Civil money penalties can reach $250,000 per violation, capped at $1 million per proceeding.
Boxed warnings come off too. FDA’s safety communications list shows it removed the amputation boxed warning from canagliflozin in August 2020, and in January 2026 it requested removal of the suicidal behavior and ideation warning from GLP-1 RA labels. A label is a living document, and sponsors with new data can argue risk down as well as see it argued up.
Our framework: how to read a new label warning
When a safety label change lands on a drug you make, buy, prescribe or invest in, run this checklist (our framework):
- Which section? Boxed, contraindication, REMS or Warnings and Precautions. The section tells you how hard FDA is leaning.
- Absolute versus relative risk. A hazard ratio of 1.4 on a rate of a few per 100,000 is a different business problem from a common reaction.
- Is it class wide? Class labeling, like the GLP-1 change, keeps competitive positions roughly level. A single product warning does not.
- What monitoring does it add? Required lab tests or specialist referrals cost clinic time and can slow uptake.
- Does it touch the REMS? Any change in distribution restrictions changes access, hub services and specialty pharmacy contracts.
- Is there a reversal path? Postmarketing studies or new analyses can support removal later, as canagliflozin showed.
What to watch next
- Revised GLP-1 RA labels posting to Drugs@FDA and any company statements from Novo Nordisk and Eli Lilly.
- The full Pimjetmi prescribing information on Drugs@FDA, which will confirm the liver monitoring language.
- Whether FDA finalizes its September 2025 draft guidance on 505(o)(4) safety labeling changes.
- New boxed warning actions on FDA’s Drug Safety Communications page.
FAQ
What is a boxed warning on a drug label?
A boxed warning, often called a black box warning, is a short, bold summary of a serious risk at the top of the prescribing information. FDA uses it for risks that are serious relative to benefit, preventable with careful use, or tied to restricted distribution.
Is a boxed warning the same as a recall?
No. A boxed warning keeps the drug on the market with a prominent caution about a serious risk. A recall or withdrawal removes product from distribution. Many widely used drugs carry boxed warnings.
What is the evidence threshold for Warnings and Precautions?
FDA’s 2011 guidance requires reasonable evidence of a causal association between the drug and the adverse event. The causal relationship does not need to be definitively established.
Did FDA put a boxed warning on Ozempic and other GLP-1 drugs for vision loss?
No. On November 9, 2026 FDA required a NAION risk statement in the Warnings and Precautions section of all GLP-1 receptor agonist labels. It is not a boxed warning.
How rare is NAION with GLP-1 drugs?
In FDA’s meta analysis of 126 randomized trials, probable NAION occurred at 6.4 events per 100,000 patient years on GLP-1 RAs versus 3.8 on placebo, based on 15 total events.
What is a REMS?
A Risk Evaluation and Mitigation Strategy is a safety program FDA can require for certain medicines with serious safety concerns, sometimes including steps like prescriber certification or required monitoring before the drug is dispensed.
Does every boxed warning come with a REMS?
No. A REMS with elements to assure safe use is one reason FDA gives for a boxed warning, but many boxed warnings exist without a REMS, and some REMS programs have no restricted distribution.
Can FDA force a company to change its label?
Yes. Under section 505(o)(4), FDA can require safety labeling changes based on new safety information. The holder must respond within 30 days, and FDA can issue an order if the parties do not agree.
Can a boxed warning be removed?
Yes. FDA removed the amputation boxed warning from canagliflozin in 2020 after reviewing new data, and in January 2026 it requested removal of a suicidal ideation warning from GLP-1 RA labels.
When is a drug contraindicated?
Only when the risk clearly outweighs any possible therapeutic benefit, and only on the basis of known hazards rather than theoretical possibilities, per FDA’s 2011 guidance.
Why do label sections matter commercially?
The section sets how prominently a risk is presented in promotion, formulary review and prescribing decisions. A boxed warning or REMS usually carries more access friction than a Warnings and Precautions entry.
Sources
- FDA, “Warnings and Precautions, Contraindications, and Boxed Warning Sections of Labeling for Human Prescription Drug and Biological Products: Content and Format,” final guidance, October 2011 (primary).
- FDA Drug Safety Communication, “FDA Requires Safety Labeling Changes for GLP-1 RAs Due to Potential Increased Risk of Rare But Serious Eye Condition,” Nov 9, 2026 (primary).
- FDA, “Safety Labeling Changes: Implementation of Section 505(o)(4) of the FD&C Act,” draft guidance, September 2025 (primary).
- FDA, Risk Evaluation and Mitigation Strategies (REMS) page (primary).
- FDA, Drug Safety Communications index, accessed Nov 11, 2026 (primary; Injectafer, canagliflozin and GLP-1 suicidal ideation entries).
- FDA, “FDA approves pexidartinib for tenosynovial giant cell tumor,” Aug 2, 2019 (primary).
- FDA, “FDA approves pimicotinib for symptomatic tenosynovial giant cell tumor,” Nov 10, 2026 (primary).
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