Dupixent Lawsuit Overview

Attorneys are reviewing claims that Dupixent (dupilumab), a top-selling biologic developed by Sanofi and Regeneron, may be linked to an increased risk of T-cell lymphomas, particularly cutaneous T-cell lymphoma (CTCL).

Since Dupixent was approved by the FDA in 2017, it has become a widely prescribed treatment for chronic inflammatory conditions, including eczema, asthma, sinusitis with nasal polyps, eosinophilic esophagitis, prurigo nodularis, and COPD with an eosinophilic phenotype. Dupixent is one of several medications prescribed for these chronic inflammatory conditions. For many patients, the drug has provided meaningful relief.

However, emerging research suggests that Dupixent may also interfere with the body’s ability to detect abnormal T-cell growth. Case reports and clinical studies indicate the drug could “unmask” or worsen hidden lymphomas mistaken for eczema. This has raised concerns that Dupixent not only failed to prevent worsening symptoms, but may have allowed hidden cancers to progress unchecked.

FDA safety reports now include hundreds of lymphoma cases from Dupixent side effects, raising questions about whether Sanofi and Regeneron failed to adequately warn doctors and patients of these risks. Understanding risk factors for CTCL is especially important for patients prescribed Dupixent and similar medications.

Who Qualifies for a Dupixent Lawsuit?

Individuals may qualify for a Dupixent lawsuit if they:

• Received Dupixent injections for eczema, asthma, sinusitis, or another approved use, and
• Were diagnosed with a T-cell lymphoma such as CTCL, mycosis fungoides, or Sézary syndrome.

It is important to consult with a Dupixent cancer lawyer to discuss your legal options and determine the best course of action for your situation.

If you or a loved one have been prescribed Dupixent and were later diagnosed with lymphoma, request a free case evaluation by submitting information about your potential claim. A free case review is available, and there are no upfront costs. Lawyers work on a contingency basis, so you only pay fees and expenses if a Dupixent lawsuit settlement or recovery is obtained.

2025 Dupixent Lawsuit Investigation Updates

• September 2, 2025 Update: The FDA’s Adverse Event Reporting System (FAERS) lists nearly 300 reports of lymphoma among Dupixent users, including 138 cases of cutaneous T-cell lymphoma (CTCL) and dozens of Sézary syndrome and other subtypes. Safety experts caution that FDA reports are voluntary and generally only ever account for between 1% and 10% of all cases, meaning the actual number of Dupixent CTCL cases is likely substantially higher.
• June 19, 2025 Update: A study published in the European Respiratory Journal by Ma et al. found asthma patients in the dupilumab group faced a 4.5-fold increased risk of CTCL compared to controls, with those treated for 16 weeks or longer showing a 14-fold increase in mature T- and NK-cell lymphomas. Researchers warned that the findings highlight the drug’s potential to accelerate hidden blood cancers.
• August 14, 2024 Update: Data from the TriNetX patient network showed atopic dermatitis patients treated with Dupixent had a 350% higher risk of CTCL compared to matched controls. The large-scale analysis provided some of the strongest population-level evidence linking Dupixent to lymphoma risk.
• May 1, 2024 Update: A study published in JAMA Dermatology reported that patients using Dupixent for eczema were about three times more likely to develop CTCL than non-users. The increased risk remained consistent even after adjusting for demographics and treatment history.
• December 17, 2020: Case reports published in the Journal of the American Academy of Dermatology (JAAD) described patients whose supposed eczema was later identified as CTCL after Dupixent treatment. In several cases, the drug appeared to “unmask” hidden lymphomas, accelerating progression once therapy began.

As a result of the growing medical and scientific research, law firms are now offering legal representation and investigating Dupixent lawsuits for affected patients, allowing families to pursue claims without any initial financial burden, since there are no fees or expenses unless they win.

About Dupixent (dupilumab)

Dupixent (dupilumab) is a biologic therapy developed by Sanofi and Regeneron, first approved by the FDA in 2017 to treat adults with atopic dermatitis.

Since then, its approvals have expanded rapidly, and the drug is now prescribed for:

• Atopic dermatitis (eczema) in adults and children
• Eosinophilic asthma
• Chronic rhinosinusitis with nasal polyps
• Eosinophilic esophagitis
• Prurigo nodularis
• COPD with an eosinophilic phenotype
• Chronic spontaneous urticaria
• Bullous pemphigoid

Dupixent works by blocking the IL-4 and IL-13 signaling pathways, which drive inflammatory immune responses. By reducing this activity, the drug helps patients manage chronic skin, respiratory, and allergic conditions that are often resistant to standard treatments. For many, Dupixent has improved quality of life by reducing flare-ups, itching, and airway inflammation.

However, a growing number of individuals have reported developing cutaneous T-cell lymphoma (CTCL), a form of non-Hodgkin’s lymphoma that begins in the skin.

Cutaneous T-Cell Lymphoma (CTCL) and Dupixent​

Cutaneous T-cell lymphoma (CTCL) is a rare, chronic form of non-Hodgkin’s lymphoma that begins in the skin. Among the various types of lymphoma reported in patients taking Dupixent, CTCL has emerged as the most common. The cancer originates in T-cells, which are white blood cells that normally help regulate the immune system, and often mimics the appearance of common skin conditions.

Symptoms of T-Cell Lymphoma

Cutaneous T-cell lymphoma (CTCL) often develops slowly, but because its early signs can closely resemble eczema or psoriasis, diagnosis is frequently delayed. Recognizing symptoms is critical for individuals prescribed Dupixent, as worsening or persistent skin changes may signal something more serious than chronic inflammation.

Common symptoms of CTCL and related subtypes include:

• Persistent red or scaly skin patches that resemble eczema or psoriasis
• Intense itching or burning that does not improve with standard treatments
• Thickened skin on the palms of your hands and the soles of your feet
• Widespread redness (erythroderma), sometimes covering large areas of the body
• Swollen lymph nodes in the neck, underarms, or groin
• Hair loss or brittle nails in more advanced disease
• Fatigue, night sweats, or unexplained weight loss if the cancer spreads internally

Because CTCL can mimic common skin conditions, patients using Dupixent should be closely monitored for symptoms that do not resolve or worsen despite therapy.

Subtypes of CTCL

Cutaneous T-cell lymphoma (CTCL) is not a single disease but a group of closely related non-Hodgkin lymphomas that primarily affect the skin. The two most frequently diagnosed subtypes are:

• Mycosis fungoides (MF): This is the most common and generally slowest-progressing form of CTCL. It often begins with patches or plaques of scaly, itchy skin that resemble eczema or psoriasis, make the cancer diagnosis difficult. Over time, the cancerous T-cells may infiltrate deeper layers of the skin and, in more advanced stages, spread to lymph nodes or internal organs. Although mycosis fungoides is considered indolent in its early stages, progression can lead to significant complications and reduced survival if it advances.
• Sézary syndrome (SS): This is a rarer but far more aggressive variant of CTCL. Unlike mycosis fungoides, Sézary syndrome involves malignant T-cells circulating in the bloodstream in addition to affecting the skin. Patients typically experience widespread redness and scaling of the skin (erythroderma), severe itching, hair loss, and enlarged lymph nodes. Because it impacts both the skin and the immune system, Sézary syndrome is harder to treat and carries a poorer prognosis compared to mycosis fungoides.

Together, these two subtypes account for the majority of CTCL cases, though there are other less common forms that also present diagnostic and treatment challenges.

Risk of Delayed or Missed Diagnosis

Since CTCL symptoms overlap so closely with atopic dermatitis, Dupixent patients may continue treatment under the belief they are managing eczema when, in fact, cancer is present.

This overlap can lead to delayed or missed diagnoses, allowing the disease to progress before it is properly identified. Physicians are urged to remain vigilant for changes in skin symptoms that fail to improve or worsen despite ongoing therapy.

Can Dupixent Cause T-Cell Lymphoma?

Research suggests that Dupixent may increase the risk of cutaneous T-cell lymphoma (CTCL) and related blood cancers. Because CTCL often resembles eczema, and the drug maker failed to provide adequate warnings for users and the medical community, the condition may go undiagnosed among Dupixent users.

By suppressing immune signals, Dupixent could mask or accelerate hidden cancers, delaying diagnosis until later stages. In advanced cases, CTCL can spread beyond the skin and lymph nodes to involve other organs, highlighting the importance of early detection.

Dupixent Linked to 300% Higher Risk of CTCL

A study published in JAMA Dermatology on April 6, 2024, found that patients with atopic dermatitis (AD) treated with Dupixent faced a sharply elevated risk of developing cutaneous T-cell lymphoma (CTCL).

Researchers analyzed large health records, controlling for age, sex, race, and excluding patients with prior immune-suppressant use to reduce bias. The analysis showed Dupixent users were more than four times as likely to develop CTCL (odds ratio 4.10). Even after adjusting for demographics and medication history, the risk remained more than doubled (OR 3.20), pointing to a consistent and concerning association between Dupixent and lymphoma that could not be explained by eczema severity alone.

Study Reinforces Dupixent Lymphoma Risks

In August 2024, another TriNetX database study further supported these findings. This analysis focused exclusively on atopic dermatitis patients, excluding individuals with other inflammatory conditions or prior biologic exposure. By closely matching patients by age, sex, and race, the researchers aimed to isolate Dupixent’s impact.

Their results revealed that Dupixent users had a 350% higher risk of developing CTCL compared to matched controls (relative risk 4.59). These findings echoed the JAMA Dermatology study, reinforcing mounting evidence of the link between side effects of Dupixent and lymphoma risks.

Dupixent Risks Extend to Asthma Patients

In June 2025, new research published in The European Respiratory Journal by Dr. Sheng-Kai Ma expanded the scope beyond eczema. Using TriNetX data, the study compared asthma patients starting Dupixent with those prescribed inhaled corticosteroids combined with a long-acting beta agonist (ICS/LABA).

Asthma patients on Dupixent faced a 4.5-fold higher risk of CTCL. Among those who continued treatment for at least 16 weeks, the risks rose even more sharply—showing a 14-fold increase in mature T- and NK-cell lymphomas, including CTCL. The findings suggest that Dupixent’s potential link to lymphoma may affect multiple patient populations.

Case Reports Raise Concerns About Dupixent and CTCL

These large-scale studies build on earlier warnings from case reports published in JAAD in 2019. Dermatologists described instances where Dupixent appeared to “unmask” or accelerate underlying CTCL in severe eczema patients. Physicians cautioned that the drug’s suppression of IL-4 and IL-13 inflammation may mask cancer symptoms that mimic eczema, delaying diagnosis until the disease is more advanced.

These early signals, once dismissed as rare, have now been reinforced by multiple large database studies, strengthening concerns that Dupixent exposure may contribute to the development or progression of T-cell lymphomas.

How Could Dupixent Cause Lymphoma?

Mounting research suggests Dupixent may play a role in triggering or accelerating certain blood cancers, particularly cutaneous T-cell lymphoma (CTCL). While no single mechanism has been confirmed, several leading theories have emerged from physicians and researchers who have observed troubling patterns among patients.

• Immune masking: By suppressing IL-4/IL-13 signaling, Dupixent may reduce inflammation that normally signals early cancer activity, delaying recognition of malignant T-cells.
• Disease misdiagnosis: CTCL symptoms can look nearly identical to eczema. Hidden lymphomas mistaken for eczema can possibly worsen when treated with Dupixent, potentially delaying accurate diagnosis and treatment. Symptoms such as unexplained pain may be a warning sign of disease progression and should prompt further medical evaluation.
• Altered T-cell dynamics: Blocking type-2 inflammation may unintentionally disrupt immune surveillance, giving abnormal T-cell clones the opportunity to expand unchecked.
• Accelerated progression: Some physicians report patients whose CTCL worsened rapidly after starting Dupixent, suggesting it may accelerate disease in those with pre-existing but undetected lymphoma.

Dupixent Lymphoma Side Effects

According to data from the FDA’s FAERS database, nearly 300 cases of lymphoma and related T-cell malignancies have been linked to Dupixent use as of late 2025:

• 138 cases of cutaneous T-cell lymphoma (CTCL)
• 104 cases of unspecified lymphoma
• 41 cases of general T-cell lymphoma
• 6 cases of Stage IV CTCL
• 5 cases of anaplastic large cell lymphoma (T- and null-cell types)
• 3 cases of Stage III CTCL
• 2 cases of angioimmunoblastic T-cell lymphoma
• 2 cases of Stage I CTCL
• 2 cases of recurrent T-cell lymphoma
• 1 case of adult T-cell lymphoma/leukemia
• 1 case of unclassifiable T-cell lymphoma

In total, 298 cases have been reported. While FAERS reports cannot always be independently confirmed, the consistency and range of lymphoma diagnoses raise serious concerns that Dupixent may be contributing to cancer development in some patients.

Dupixent Side Effects Beyond Lymphoma

While concerns about lymphoma risks are driving ongoing Dupixent lawsuit investigations, the medication has also been associated with a range of other side effects that patients and doctors should monitor closely.

Many of these complications are linked to Dupixent’s role in suppressing inflammatory pathways, which can alter how the immune system responds in different parts of the body.

• Eye Disorders (Conjunctivitis, Keratitis): One of the most frequently reported side effects involves eye inflammation. Patients have experienced conjunctivitis (pink eye), keratitis (corneal inflammation), and dry eye symptoms. In some cases, these issues require ophthalmologic treatment to prevent long-term damage.
• Eosinophilia (High White Blood Cell Counts): Dupixent may trigger abnormally high levels of eosinophils, a type of white blood cell involved in allergic responses. Eosinophilia can cause tissue inflammation and, in rare cases, damage to organs such as the lungs or heart.
• Injection Site Reactions: Redness, swelling, itching, and pain at the injection site are among the most common Dupixent side effects. These reactions are usually mild but can be persistent in long-term users.
• Hypersensitivity and Allergic Reactions: Some patients report severe allergic responses after Dupixent injections, ranging from rash and hives to systemic reactions. Although rare, these events may require discontinuation of the drug and emergency medical care.

Is There a Dupixent Class Action Lawsuit?

As of now, no Dupixent lawsuits have been formally filed in U.S. courts, and there is not yet a consolidated class action or multidistrict litigation (MDL). However, attorneys across the country are actively reviewing claims and evaluating several different types of legal actions that could be pursued if case numbers continue to grow.

• Individual Product Liability Dupixent Lawsuits: The most likely path for patients already diagnosed with lymphoma is an individual personal injury lawsuit. These claims are brought directly against Sanofi and Regeneron, alleging that the drugmakers failed to adequately warn about the potential cancer risks. If successful, individual lawsuits may provide compensation for medical bills, lost income, pain and suffering, and other damages tied to a patient’s diagnosis.
• Dupixent Class Action Lawsuits: While not yet filed, attorneys could also consider a class action lawsuit on behalf of Dupixent users. A class action would not focus on personal injury damages for a single patient, but instead seek economic recovery for a larger group, such as the cost of the drug or uniform medical expenses. Dupixent class actions lawsuits may also push for changes to the drug’s warning label or patient instructions.
• Medical Monitoring Claims: Another possible claim type is a medical monitoring class action. These lawsuits seek court-ordered programs to provide ongoing cancer screenings for Dupixent users who may face a heightened risk of developing lymphoma. Instead of waiting for a diagnosis, medical monitoring actions aim to detect disease earlier and reduce long-term harm for patients exposed to the drug.

Contact a Dupixent T-Cell Lymphoma Lawyer

If you or a loved one were prescribed Dupixent and later developed CTCL or another form of T-cell lymphoma, you may be entitled compensation through a Dupixent lawsuit.

Dupixent T-Cell Lymphoma lawyers are providing free consultations to help individuals and families understand their rights, investigate potential claims, and hold manufacturers accountable.

These cases are handled on a contingency fee basis, so there are no upfront costs or fees unless a recovery is obtained through a settlement or jury verdict.