What Is Dupixent (Dupilumab)?

Dupixent is the brand name for dupilumab, a biologic medication developed by Regeneron and Sanofi that has become the most versatile treatment in the history of type 2 inflammatory (Th2-driven) diseases. Since its first FDA approval for atopic dermatitis in 2017, Dupixent has accumulated approvals for more than seven conditions — asthma, chronic rhinosinusitis with nasal polyps, eosinophilic esophagitis, prurigo nodularis, chronic spontaneous urticaria, and more — all driven by the same underlying Th2 immune pathway that dupilumab blocks.

The Mechanism: Blocking the Th2 Immune Pathway

The immune system broadly divides its responses into different "flavors" of helper T-cell activity. Th2 inflammation — driven by the cytokines IL-4 and IL-13 — is associated with allergic and atopic conditions. IL-4 and IL-13 are produced by various immune cells including T helper 2 cells, innate lymphoid cells type 2 (ILC2s), and mast cells, and they signal through a shared receptor component: the IL-4 receptor alpha (IL-4Rα) subunit.

Dupilumab is a fully human monoclonal antibody that binds specifically to the IL-4Rα subunit, blocking the signaling of both IL-4 and IL-13 simultaneously. This is important — it's not just blocking one cytokine, but rather the shared receptor through which both key Th2 drivers signal. By interrupting this pathway, dupilumab reduces the chronic Th2-driven inflammation that underlies atopic dermatitis, allergic asthma, nasal polyp growth, and eosinophilic esophageal inflammation.

FDA-Approved Indications

Why Dupixent Is Different from Steroids

Before dupilumab, moderate-to-severe atopic dermatitis in adults was largely managed with topical or systemic corticosteroids, cyclosporine, or methotrexate — all of which produce broad immunosuppression and carry significant long-term risks including osteoporosis, metabolic syndrome, nephrotoxicity, and systemic immunosuppression. Dupilumab's targeted blockade of IL-4/IL-13 signaling avoids these problems because it only suppresses a specific arm of immune signaling rather than broadly dampening immune function.

Side Effects

Injection site reactions

Pain, redness, and swelling at the injection site are among the most common side effects. Dupixent is administered as a subcutaneous injection, typically every two weeks (or monthly for some indications), using a pre-filled syringe or autoinjector pen. Letting the pen reach room temperature before injecting and rotating sites reduces discomfort.

Conjunctivitis

Eye inflammation — specifically conjunctivitis (and related conditions including blepharitis and keratoconjunctivitis) — is a distinctive and relatively common side effect of dupilumab, particularly in patients using it for atopic dermatitis. This side effect is not seen at the same rate in asthma or CRSwNP trials, suggesting it may be related to the specific immune context of atopic dermatitis rather than the drug itself in all populations. Patients should report persistent eye redness, discharge, or irritation to their provider and may benefit from ophthalmology evaluation and lubricating eye drops.

Eosinophilia

Transient elevations in blood eosinophil counts have been observed with dupilumab. In most patients these are mild and asymptomatic, but rarely, significant eosinophilia requiring evaluation has occurred. Patients with underlying eosinophilic conditions should be monitored.

Cost and Access

Dupixent's annual list price is approximately $35,000–$40,000 per year, placing it in the range typical for biologics used in atopic disease. Insurance coverage is generally available for approved indications with prior authorization. Regeneron and Sanofi offer a MyWay patient assistance program for eligible patients. Biosimilars to dupilumab are under development and may improve access and cost over the coming years, though as of mid-2026, no dupilumab biosimilars are yet commercially available in the United States.

Frequently Asked Questions