FDA Warns About Dupixent and Skin Cancer Risk

In March 2025, the U.S. Food and Drug Administration took a step that the manufacturer of Dupixent had been resisting for years: it publicly identified the drug as a potential cause of cutaneous T-cell lymphoma (CTCL) — a rare and aggressive form of skin cancer.

The action came not as a recall, not as a black-box warning, and not as a label change. It came as an addition to the FDA’s quarterly Potential Signals of Serious Risk list — the agency’s way of formally telling physicians, patients, and the manufacturer that the adverse event data has crossed a threshold that requires regulatory review.

For the more than one million patients globally who currently use Dupixent — and the families of those who’ve already been diagnosed with CTCL after using it — the FDA’s action represents the first formal acknowledgment from a regulator that the link is real enough to investigate.

This is what the FDA actually said, what it didn’t say, and what it means for patients and prescribers.

What the FDA Did in March 2025

The FDA maintains a quarterly publication called “Potential Signals of Serious Risks/New Safety Information Identified by the FDA Adverse Event Reporting System (FAERS).” It’s the agency’s mechanism for publicly flagging drugs whose post-market adverse event data has produced a statistical signal worth investigating.

In the Q1 2025 report, the FDA added Dupixent (dupilumab) to the list. The cited concern: cutaneous T-cell lymphoma, including mycosis fungoides and Sézary syndrome.

The FDA confirmed it received more than 300 reports of CTCL linked to Dupixent through FAERS, and stated that the agency is “evaluating the need for regulatory action.” That language is important. In FDA practice, “evaluating the need for regulatory action” is the immediate predicate for a possible:

• New black box warning
• Updated product label
• Required physician letter (Dear Healthcare Provider letter)
• Required REMS (Risk Evaluation and Mitigation Strategy) program
• Required additional studies
• Withdrawal of approval (rare, but on the table)

You can look up current Dupixent adverse event data at the FDA’s FAERS Public Dashboard and drug safety reporting portal.

What the FDA Didn’t Do (Yet)

As of the date of publication of this article, the FDA has not:

• Recalled Dupixent
• Required a black box warning
• Updated the U.S. prescribing information to mention CTCL
• Issued a Dear Healthcare Provider letter
• Required a REMS program

The current U.S. label for Dupixent — even after the March 2025 signal — contains no warning about cancer risk. The agency’s review remains ongoing.

This gap — between a publicly identified safety signal and the absence of any warning to prescribers — is the central premise of the lawsuits now being filed against Dupixent’s manufacturers.

The Science the FDA Is Reacting To

The CTCL signal didn’t come out of nowhere. By the time the FDA acted in March 2025, multiple peer-reviewed studies had already documented elevated CTCL rates in Dupixent users:

The 2024 Dermatologic Therapy Study

A retrospective analysis of nearly 20,000 atopic dermatitis patients found that those treated with Dupixent were roughly 4.6 times more likely to be diagnosed with CTCL than patients who didn’t use the drug. The majority of CTCL diagnoses occurred within the first year of treatment.

The 2025 Journal of Allergy and Clinical Immunology Analysis

A pharmacovigilance analysis of FDA Adverse Event Reporting System data found that CTCL was reported in Dupixent users at rates approximately 30 times higher than in users of other medications — an extreme disproportionality signal.

The 2025 European Respiratory Journal Study

A separate study focused on asthma patients on Dupixent found a 79% higher risk of lymphoma overall and a 4.5-fold increased risk of T-cell and natural killer cell lymphomas.

The 2024 Hasan et al. Study

A large database study published in April 2024 found that dupilumab-treated patients had significantly elevated odds ratios for CTCL diagnosis after adjusting for age and other factors.

The studies don’t agree on every detail. Some focus on whether Dupixent causes CTCL, others on whether it unmasks CTCL that was already present, and others on whether it accelerates disease that would have progressed regardless. The FDA’s regulatory action treats those mechanistic questions as secondary to the central pattern: patients on Dupixent are being diagnosed with CTCL more often than expected, and earlier in adult life than the disease typically appears.

What “Masking” Actually Means

Dupixent works by blocking signaling through the IL-4 and IL-13 immune pathways. These pathways drive the inflammation that produces eczema’s redness, itching, and scaling.

Early-stage CTCL — particularly mycosis fungoides — looks remarkably like eczema. Both produce itchy, red, scaly patches that respond, at least partially, to anti-inflammatory treatment.

The clinical concern is that when Dupixent suppresses the inflammatory response, it can suppress the visible symptoms of CTCL while the underlying disease continues to progress. By the time the rash returns or worsens despite continued treatment, the cancer may have advanced from a localized patch stage to a more aggressive stage involving lymph nodes or blood.

A 2025 systematic review specifically examined whether dupilumab-treated patients were being diagnosed with mycosis fungoides at more advanced stages than would be expected. The literature remains divided on whether this represents drug-driven progression, delayed diagnosis from masked symptoms, or both. What’s not in dispute is that some patients are being diagnosed later than they would have been without the drug.

What’s Happening in the Litigation

As of early 2026, lawsuits against Sanofi and Regeneron — the companies that market and manufacture Dupixent — have been filed in federal courts across the country. The core allegations:

• The manufacturers knew or should have known about the CTCL link from peer-reviewed studies, FDA adverse event reports, and case series presented at dermatology conferences
• They failed to warn prescribers and patients
• They failed to update the label as evidence accumulated
• They continued to market Dupixent as safe for chronic, long-term use without disclosing the emerging risks

In October 2025, a Tennessee family filed one of the country’s first wrongful death lawsuits over Dupixent and CTCL — alleging their mother died of T-cell lymphoma months after starting the drug. In December 2025, a separate case was filed alleging both mycosis fungoides and Sézary syndrome diagnoses linked to dupilumab use. In February 2026, plaintiffs filed a motion to consolidate Dupixent cases into a federal multidistrict litigation (MDL), which would centralize pretrial proceedings nationwide.

No verdicts or settlements have been reached yet, and the MDL motion remains pending.

What the FDA Action Means for Patients

If you’re currently on Dupixent:

• Don’t stop the drug abruptly. Sudden discontinuation of a biologic carries its own risks. Coordinate any change with your prescribing physician.
• Talk to your doctor about your current symptoms. A rash that has changed in appearance, returned despite treatment, or developed in atypical patterns warrants discussion.
• Know the symptoms of CTCL. Persistent or growing patches in sun-protected areas (lower trunk, buttocks, breasts), thickened or raised plaques, swollen lymph nodes, unexplained weight loss, or new tumor-like nodules all deserve evaluation.
• Ask about a biopsy if your dermatologist hasn’t done one recently, particularly if your symptoms are atypical or treatment-resistant.

If you’ve already been diagnosed with CTCL after Dupixent use:

• Get the diagnosis confirmed by a dermatopathologist with cutaneous lymphoma expertise. Diagnostic accuracy matters enormously in early CTCL.
• Consider referral to a specialized cutaneous lymphoma program. Centers like Penn Medicine, Memorial Sloan Kettering, MD Anderson, and others run major referral programs nationally; Vanderbilt and other Tennessee academic centers can also evaluate and treat.
• Preserve your prescription records, medical records, and pharmacy history. Your case will turn on the specific timeline of treatment and diagnosis.
• Talk to a lawyer who handles defective drug cases. The window to act is shorter than most people realize.

For more on the underlying drug and the symptoms patients should watch for, see our overview of Dupixent side effects your doctor may not have warned you about and our Dupixent lawsuit page tracking the litigation.

Tennessee Filing Deadlines

Tennessee has one of the shortest personal injury filing deadlines in the country. Under Tenn. Code § 28-3-104, the statute of limitations is generally one year from the date of injury — with discovery rule exceptions that can extend it in some drug-injury cases where the connection between the drug and the harm wasn’t immediately apparent.

Tennessee also imposes a statute of repose under Tenn. Code § 29-28-103 for product liability claims. The interaction of these deadlines is fact-specific. Don’t assume you have more time than the shortest applicable period.

You Don’t Pay Unless We Win

The Higgins Firm is actively reviewing Dupixent CTCL cases for patients in Tennessee, Kentucky, Georgia, and Texas. Free, confidential consultation. Contingency fee — you owe nothing unless we recover for you.

The FDA’s March 2025 action doesn’t prove the case. But it does mean that what was once dismissed as “rare anecdote” is now a publicly identified safety signal under federal review. Patients who were never warned — and the families of those who weren’t around to be warned — deserve answers.