If you have severe eczema, you know what Dupixent meant when it arrived in 2017. Skin that had itched and cracked for decades cleared in weeks. Sleep returned. It became one of the best-selling drugs in the world, with millions of patients across eczema, asthma, and other conditions.
The patients now suing Sanofi and Regeneron describe that same relief, followed by something else: patches that came back and did not respond, lymph nodes that swelled, a biopsy, and a diagnosis of cutaneous T-cell lymphoma — a rare blood cancer that lives in the skin and, in its early stages, is routinely mistaken for eczema.
How patients describe it
Years of "eczema." Many had been treated for atopic dermatitis for a decade or more before Dupixent. Some, the lawsuits allege, had early CTCL all along, misdiagnosed because the two conditions look alike.
Improvement, then a different pattern. Skin cleared, then new lesions appeared — thicker plaques, tumors, or widespread redness. Dermatologists increased doses or added treatments before considering biopsy.
Diagnosis at a later stage. By the time CTCL was identified, several patients allege it had progressed. Advanced CTCL is difficult to treat; at least one filed case involves a death from peripheral T-cell lymphoma.
Nearly 300 reports of T-cell lymphoma in Dupixent patients have reached the FDA, which is evaluating whether regulatory action is needed. In June 2026, federal cases were consolidated as MDL 3180.
Direct2Attorney · Litigation UpdateThe two theories
Unmasking / masking
Delayed diagnosis- Dupixent suppresses the inflammation that made lesions visible
- Underlying CTCL progresses while skin looks better
- Diagnosis comes at a more advanced stage
- Plaintiffs allege the label should have required screening
Acceleration
Disease progression- Blocking IL-4 and IL-13 may shift immune signaling
- Studies report CTCL risk several times higher in treated patients
- Case series describe rapid progression after starting the drug
- Manufacturers dispute causation
What patients want others to know
Ask for a biopsy when eczema behaves differently. Ask specifically whether CTCL has been ruled out. Keep the pen boxes, the prescription records, and photos of skin changes over time. And understand that a rare complication of a widely used drug still affects real people — enough of them that a federal court has now organized their cases.
What this means if you're considering a claim
If you used Dupixent and were diagnosed with cutaneous T-cell lymphoma or another T-cell lymphoma, a claim may exist. The MDL is new and accepting cases. A free review confirms the drug, the diagnosis, and your state’s deadline.
Diagnosed with T-cell lymphoma after Dupixent?
Free, confidential review. No upfront cost, no obligation.
Common Questions
Timing is part of the causation analysis. Diagnoses during use or within a period afterward are the focus, but each case is evaluated individually.
Mycosis fungoides is the most common form of CTCL and is central to the litigation.
Do not change medication without your prescriber. The lawsuit is about warnings, not about whether the drug is right for you now.
Yes. Wrongful death claims are part of the litigation.
No. Direct2Attorney’s review is free, and participating law firms typically work on contingency, meaning fees are generally paid only if there is a recovery. Confirm fee terms in writing with the firm.
