Dupixent Cancer Risks Outlined in User Stories, as Evidence Mounts of T-Cell Lymphoma Link

Stories of lymphoma diagnosis after using Dupixent continue to surface amid an FDA investigation, and the filing of the first Dupixent cancer lawsuit last week.

Individuals who turned to Dupixent for relief from chronic skin problems are now sharing devastating accounts of being diagnosed with cutaneous T-cell lymphoma (CTCL), a rare and aggressive cancer that many say was hidden until it was too late.

For years, Dupixent has been marketed as a breakthrough biologic for eczema and other inflammatory conditions, helping millions manage relentless itch and skin inflammation.

However, emerging research, a surge in FDA safety reports and at least one lawsuit are beginning to paint a troubling picture for some users, who claim Dupixent may have masked or accelerated early signs of cancer, delaying their diagnosis until the disease had already advanced.

Amid these growing concerns, the FDA has launched a formal safety review into Dupixent’s potential link to CTCL, following hundreds of lymphoma reports submitted by doctors and patients.

This review has been further substantiated by recent studies published in JAMA Dermatology, The European Respiratory Journal and other peer-reviewed journals that have found Dupixent users may face three- to fourfold higher risks of developing CTCL, adding urgency to concerns about whether the drug’s benefits have overshadowed undisclosed dangers.

Earlier this month, a Dupixent wrongful death lawsuit was filed in Tennessee, alleging that the drug triggered or accelerated a fatal form of T-cell lymphoma in a woman who died just months after starting treatment. Attorneys say it could be the first in a wave of Dupixent CTCL lawsuits to be filed, as more evidence emerges linking Dupixent to CTCL and as the FDA considers whether a warning label update is necessary to alert doctors and patients about these potential cancer risks.

At the same time, patients and families are flooding online communities with stories of worsening rashes, failed treatments and sudden cancer diagnoses. Many describe months of uncertainty before receiving a proper diagnosis, experiences that are now prompting deeper scrutiny of Dupixent’s CTCL side effects.

Dupixent CTCL Stories

In this featured post, AboutLawsuits highlights firsthand accounts from Dupixent users who say their eczema treatment took a devastating turn. These stories, shared on public forums and within the site’s own comment sections, reflect a troubling pattern of misdiagnosis, delayed detection and life-changing outcomes now under scrutiny by federal health regulators.

Dupixent CTCL Diagnosis Stories

Some of the most harrowing Dupixent testimonials come from patients who believed they were finally managing eczema, only to learn that they had developed a rare form of blood cancer.

“Last March my husband was prescribed Dupixent for atopic dermatitis… A week after the first injection, his entire body was bright red. Several months later, strange bumps appeared on his arms. A biopsy confirmed Cutaneous T-Cell Lymphoma. The oncologist said the lymphoma was dormant until it was provoked by the Dupixent. He is stage 3a. There is no cure. The skin lymphoma covers more than 60% of his body.”
– M, January 2023

This account reflects what researchers and dermatologists have long cautioned: CTCL can mimic eczema, leading to dangerous delays in diagnosis. Some physicians now warn that Dupixent’s immune-modulating effects may allow hidden cancers to progress more aggressively, giving the illusion of a chronic rash that resists treatment.

Another Dupixent user shared a nearly identical experience on Reddit, explaining that lifelong patchy skin flared into relentless itch earlier this year. After roughly six months on Dupixent with no relief, her dermatologist ordered a biopsy that confirmed cutaneous T-cell lymphoma (CTCL). The poster said she was still in shock, awaiting a specialist appointment and struggling to process how a supposed eczema therapy could have been connected to her cancer diagnosis.

Because CTCL so often resembles stubborn dermatitis, patients may remain on Dupixent for months while cancer spreads undetected. Many of these stories illustrate the critical need for re-evaluation when symptoms worsen or fail to respond, particularly when skin lesions change shape, color or texture despite continued treatment.

Dupixent Misdiagnosis and Delay

Since cutaneous T-cell lymphoma can appear nearly identical to eczema or psoriasis, some Dupixent users describe being misdiagnosed or dismissed by physicians, even as their conditions grew more severe.

“My son was taking Dupixent for severe skin eczema – it only made it worse to the point that it was unbearable for him to even sleep. Allergist sent in a biopsy and it shows that he has Cutaneous T-Cell Lymphoma. Doctors ignored the high white blood count and said it could be just the Dupixent – if we would have ignored this who knows if it would have gotten worse.”
– Millie, June 2024

These stories highlight how Dupixent’s anti-inflammatory effects can mask early warning signs, such as elevated blood counts or spreading lesions, delaying cancer detection until the disease is advanced.

Researchers who have released findings suggesting a link between Dupixent and CTCL have almost unanimously emphasized that persistent or worsening rashes while on Dupixent should always prompt a biopsy to rule out lymphoma, even in younger or otherwise healthy patients.

Dupixent Sézary Syndrome and Advanced CTCL Stories

Another Reddit user recounted her husband’s devastating experience with Dupixent, which began as a standard eczema treatment and ended with a diagnosis of Sézary syndrome, one of the most aggressive forms of CTCL.

Her 47-year-old husband’s eczema worsened soon after starting Dupixent. By the third injection, the reactions were severe, and treatment was stopped. A shave biopsy initially read lichenoid eruption, a nonspecific rash pattern often mistaken for inflammation rather than malignancy.

However, she indicates that his white blood cell count remained between 25,000 and 30,000 per microliter for more than a year, far above the normal range of 4,000 to 11,000.

After months of inconclusive results, the family sought a second opinion at MD Anderson Cancer Center. There, a new biopsy and flow cytometry confirmed Sézary syndrome with mycosis fungoides, both classified as CTCL subtypes.

Sézary syndrome is considered an advanced stage of cutaneous T-cell lymphoma, in which cancerous T-cells spread from the skin into the bloodstream, often causing widespread redness, swelling and intense itching. Because early symptoms can appear identical to eczema, it remains one of the most commonly misdiagnosed skin cancers among long-term Dupixent users.

He began antibody therapy with mogamulizumab, and his white cell count dropped dramatically after treatment began.

“This is only a fraction of what we have endured post Dupixent, not 100% positive there is any correlation but it sure seems like it, if you take anything from reading this please do your research, trust your gut, research and advocate for yourself or your family.”
– DenThom427 (reddit) 2025

Which Cancers Have Been Linked to Dupixent?

Recent safety reports and peer-reviewed studies suggest that Dupixent (dupilumab) may be associated with several types of T-cell lymphomas, rare cancers that begin in white blood cells responsible for immune function.

While the most common form identified among users is cutaneous T-cell lymphoma (CTCL), other aggressive subtypes have also been reported in FDA data and medical literature.

Types of Lymphomas Reported Among Dupixent Users

• Cutaneous T-Cell Lymphoma (CTCL) – the most frequent cancer reported among Dupixent users, affecting the skin and sometimes spreading internally.
  • Mycosis Fungoides (MF) – the most common CTCL subtype, typically beginning as scaly, eczema-like patches that can progress to tumors or systemic disease.
  • Sézary Syndrome (SS) – an advanced CTCL variant in which malignant T-cells circulate in the blood, leading to widespread redness, swelling and intense itching.
• Peripheral T-Cell Lymphoma (PTCL) – a fast-growing systemic lymphoma that can impact lymph nodes, organs and bone marrow.
• Anaplastic Large Cell Lymphoma (ALCL) – a rare T-cell lymphoma that can arise in the skin or lymph nodes, occasionally linked to immune-modulating therapies.
• Angioimmunoblastic T-Cell Lymphoma (AITL) – an aggressive form characterized by fever, rash and enlarged lymph nodes.

Over the past two years, mounting research has reinforced these concerns. In April 2024, a study published in JAMA Dermatology found that patients with atopic dermatitis treated with Dupixent were four times more likely to develop CTCL than those who were not exposed to the drug. Even after controlling for age, sex and disease severity, the risk remained statistically significant.

A follow-up analysis in August 2024 using the TriNetX real-world database confirmed those findings, showing a 350% higher risk of CTCL among Dupixent users compared to matched controls. Researchers emphasized that the increased risk could not be explained by underlying eczema alone.

Then, in June 2025, a study published in The European Respiratory Journal extended the findings beyond eczema patients, examining asthma users of Dupixent. It found a 4.5-fold higher risk of CTCL, and among patients treated for 16 weeks or longer, a 14-fold increase in mature T- and NK-cell lymphomas, a category that includes CTCL and PTCL.

These findings, combined with nearly 300 adverse event reports submitted to the FDA citing lymphoma among Dupixent users, have intensified scrutiny over the drug’s long-term safety and prompted regulators to consider whether stronger cancer warnings should be added to the label.

Dupixent and CTCL: A Pattern That Demands Answers

Mounting evidence now shows a consistent and troubling pattern. Across published studies, FDA safety data and patient stories, Dupixent has been repeatedly linked to T-cell lymphomas, including cutaneous T-cell lymphoma (CTCL).

Many users describe similar experiences with worsening rashes, months of misdiagnosis and eventual cancer diagnoses that may have been masked by Dupixent’s immune-suppressing effects. Researchers warn that by blocking key immune pathways, the drug may inadvertently unmask dormant cancers or allow abnormal T-cells to grow unchecked.

As evidence unfolds, former users are now pursuing Dupixent lawsuits against Sanofi and Regeneron, alleging the companies failed to warn about CTCL risks. Attorneys are reviewing claims for individuals diagnosed with CTCL, Sézary syndrome or other T-cell lymphomas after using Dupixent.

Dupixent cancer lawyers provide free consultations, and all lawsuits are handled on a contingency fee basis, meaning there are no costs or attorney fees unless a recovery is obtained through a settlement or verdict.