How to File a Dupixent Lawsuit: A Guide for Patients

Dupixent cancer litigation is at an early stage, which means the process for filing a claim is different from more established MDLs. There is no central federal court or standardized Plaintiff Fact Sheet as of early 2026. This guide explains what the filing process looks like now, who is eligible, and what records are essential for a successful case evaluation.

Step 1: Determine if Your Case Has the Core Elements

Before investing time and emotional energy, it's important to assess whether your situation aligns with the core facts of viable Dupixent claims. Attorneys evaluating these cases generally look for:

• Significant Dupixent Use: You were prescribed and used Dupixent for an extended period, typically at least one year, for an FDA-approved condition like atopic dermatitis, asthma, or COPD.
• A Qualifying Cancer Diagnosis: You were diagnosed with a qualifying cancer *after* starting Dupixent. The most prominent signal in post-marketing data is for lymphoma, particularly Cutaneous T-Cell Lymphoma (CTCL), but other malignancies may also be considered.
• A Clear Timeline: The cancer diagnosis must have occurred after you began treatment. A pre-existing cancer diagnosis that was stable and then progressed after starting Dupixent may also qualify, but this requires more detailed medical expert review.
• Viable Statute of Limitations: Each state has a deadline (statute of limitations) for filing personal injury claims. This is typically 1-3 years from the date you knew or should have known that your injury might be connected to the drug. An attorney can determine the specific deadline for your state.

Step 2: Gather Your Medical and Pharmacy Records

Documentation is the foundation of any pharmaceutical injury claim. The more complete your records are, the faster and more accurately an attorney can evaluate your case. You will need:

• Pharmacy Records: A complete history from your pharmacy showing every Dupixent prescription fill date, dosage, and prescribing doctor. This is the best evidence of your exposure history.
• Prescribing Physician Records: Records from the dermatologist, allergist, or pulmonologist who prescribed Dupixent. These notes document why it was prescribed and how your condition was monitored.
• Oncology Records: All records related to your cancer diagnosis, including the initial biopsy/pathology report, all imaging (CT/PET scans), treatment notes (chemotherapy, radiation, surgery), and follow-up visit notes. The pathology report confirming the specific cancer type is critical.
• Primary Care Physician Records: Your general medical records provide baseline health information and can help rule out other potential causes.

You can request these records directly from each provider's medical records department. Under HIPAA, they are required to provide you with a copy, though there may be a small copying fee.

Step 3: Create a Personal Timeline

Organize the key dates into a simple, one-page timeline. This will be invaluable for both you and your legal team. Include:

• Date you were first diagnosed with the condition for which you took Dupixent (e.g., atopic dermatitis).
• Date you first started taking Dupixent.
• Date you stopped taking Dupixent (if applicable).
• Date you first noticed cancer-related symptoms.
• Date of your official cancer diagnosis.
• Key treatment dates (surgery, start of chemotherapy, etc.).

Step 4: The Legal Consultation and Intake Process

Once you have your basic timeline and have started gathering records, the next step is a free consultation with a law firm that specializes in pharmaceutical litigation. Here’s what to expect:

• Initial Call: You will speak with an intake specialist who will ask for the basic facts of your case: the drug, the injury, and the timeline. This call is confidential and does not obligate you to anything.
• Medical Records Review: If your case appears to have the core elements, the firm will ask you to sign medical release authorizations (HIPAA forms) so they can obtain and review your records directly. This review is done by paralegals, nurses, and attorneys on staff and is still free of charge.
• Case Evaluation: The legal team will thoroughly review your records to confirm the diagnosis, exposure history, and timeline. They will also bring in medical experts to assess the strength of the causal link between Dupixent and your specific cancer.
• Decision to Retain: If the firm believes you have a strong, viable claim, they will offer to represent you. You will sign a retainer agreement, which outlines the terms. Pharmaceutical cases are handled on a contingency fee basis, meaning you pay no upfront fees. The law firm is paid a percentage of any settlement or verdict they obtain for you. If there is no recovery, you owe no attorney's fees.

Step 5: Filing the Lawsuit and the Litigation Process

After you retain counsel, your legal team handles all aspects of the lawsuit:

• Drafting and Filing: Your attorney will draft a formal complaint detailing the facts of your case and the legal claims against the manufacturers (Sanofi and Regeneron). This is filed in the appropriate court.
• Discovery: This is the longest phase of litigation. Both sides exchange documents and evidence. Your attorneys will seek internal documents from the drug companies about what they knew about cancer risks and when. You will likely have to provide some written answers to questions (interrogatories) and may have your deposition taken.
• Expert Witnesses: Both sides will hire medical and scientific experts to provide opinions on whether Dupixent caused your cancer. These expert opinions are critical to the case.
• MDL Consolidation Watch: As more Dupixent cases are filed, they may be consolidated into a Multi-District Litigation (MDL) to streamline the process. Your case would be transferred to the MDL court for pretrial proceedings.
• Resolution: Cases can be resolved through a settlement with the defendants or, in rare cases, by going to trial. Most large pharmaceutical litigations are resolved through global settlements after a few "bellwether" cases go to trial and establish verdict ranges.

What to Expect in Early-Stage Litigation

Because Dupixent cancer litigation is not yet a mature MDL, the timeline is less predictable. Cases are being filed and litigated individually, which means the process can be slower. The scientific evidence is still developing, which adds a layer of complexity. An experienced pharmaceutical attorney will be upfront about this uncertainty while building the strongest possible case based on the evidence available today.

Related Pages on This Site

• Dupixent Cancer Risk: What Patients Should Know
• FDA Dupixent Warnings and Safety Updates
• Check Your Eligibility