Dupixent (dupilumab) works by blocking two specific inflammatory signals, IL-4 and IL-13, that drive the chronic inflammation responsible for nasal polyp growth. It does this by targeting a shared receptor called IL-4Rα on cell surfaces, which both of these signals use to communicate. By sitting on that receptor, Dupixent prevents IL-4 and IL-13 from delivering their messages, effectively turning down the inflammatory process that causes polyps to form, grow, and recur.
The Inflammation Behind Nasal Polyps
Nasal polyps develop from a specific pattern of chronic inflammation known as type 2 inflammation. In this process, the immune system produces excessive amounts of IL-4 and IL-13, two signaling molecules (cytokines) that act as upstream commanders. They don’t just trigger inflammation on their own. They recruit other immune cells, promote mucus overproduction, and drive tissue remodeling, which is the physical swelling and reshaping that becomes a polyp.
What makes IL-4 and IL-13 especially important is that they sustain the cycle. Even after polyps are surgically removed, these signals can keep the underlying inflammation going, which is why polyps so often grow back. Dupixent interrupts this loop at its source rather than managing symptoms downstream. Because both IL-4 and IL-13 rely on the same receptor subunit (IL-4Rα) to function, a single antibody can block both pathways simultaneously.
What Dupixent Does to Polyp Size and Congestion
Two large clinical trials, SINUS-24 and SINUS-52, tested Dupixent in adults with severe chronic sinusitis and nasal polyps who hadn’t responded well to standard treatments. At 24 weeks, patients on Dupixent had significantly smaller polyps compared to those on placebo, with an average nasal polyp score improvement of about 2 points. That may sound modest as a number, but on the scoring scale used (which rates polyps in each nostril from 0 to 4), a 2-point reduction can mean the difference between polyps that block the nasal passage and polyps that have retreated enough to restore airflow.
Congestion scores improved meaningfully as well. Patients reported roughly a 0.9-point improvement in nasal obstruction compared to placebo on a 0-to-3 severity scale. CT scans told a similar story: sinus opacification (the cloudy blockage visible on imaging) dropped substantially, with Lund-Mackay scores improving by over 7 points in one trial and over 5 in the other. These aren’t subtle imaging findings. They reflect genuinely clearer sinuses.
Restoring Lost Sense of Smell
Loss of smell is one of the most frustrating symptoms of nasal polyps, and it’s nearly universal. In the clinical trials, about 80% of patients had complete loss of smell (anosmia) at the start of treatment. By week 24, the proportion of Dupixent-treated patients with anosmia dropped from roughly 81% to 28.5%. Nearly 15% of patients on Dupixent recovered normal smell, compared to just 1.2% on placebo. Those results held steady through week 52.
The improvement in smell also correlated with improvements in polyp size and congestion, which makes biological sense. As polyps shrink and inflammation recedes, odor molecules can reach the smell receptors high in the nasal cavity again. For many patients, this is the benefit they notice most in daily life.
Reducing the Need for Surgery and Steroids
One of the strongest practical arguments for Dupixent is what it prevents. In a pooled analysis of trial data, Dupixent reduced the number of patients needing sinus surgery by about 83% compared to placebo. It also cut the need for systemic corticosteroid courses (oral steroids like prednisone) by roughly 74%. This matters because repeated courses of oral steroids carry real long-term risks, including bone thinning, weight gain, and elevated blood sugar. And repeat sinus surgeries become progressively less effective for many patients. Dupixent offers a way to break that cycle of surgery, temporary relief, and regrowth.
Who Is Eligible for Treatment
The FDA approved Dupixent as an add-on maintenance treatment for patients aged 12 and older with inadequately controlled chronic rhinosinusitis with nasal polyps. “Inadequately controlled” is the key phrase. You don’t start here. Dupixent is typically prescribed after nasal corticosteroid sprays, saline rinses, and often oral steroids or prior surgery have failed to keep polyps under control. The clinical trials specifically enrolled patients who had already had sinus surgery or systemic steroid treatment, or who couldn’t tolerate those options.
Your doctor will assess whether your polyps represent the type 2 inflammatory pattern that Dupixent targets. Not every case of chronic sinusitis involves this pathway, and Dupixent won’t help with polyps driven by other mechanisms.
Side Effects to Expect
The most common side effect is injection site reactions. In one trial, 40% of patients on Dupixent reported redness, swelling, or discomfort at the injection site, compared to 7% on placebo. These reactions are typically mild and tend to lessen over time. Dupixent is given as a subcutaneous injection every two weeks, so injection site irritation is something you’ll manage regularly.
Some patients also experience a temporary rise in a type of white blood cell called eosinophils. This can sound alarming, but it’s generally a transient effect of blocking the inflammatory pathway, as eosinophils that were being pulled into the nasal tissue redistribute into the blood. Serious side effects are uncommon. The trials found Dupixent to be well tolerated overall, even over 52 weeks of continuous use.
How Treatment Works in Practice
Dupixent is self-injected at home using a pre-filled syringe or autoinjector. The typical schedule is one injection every two weeks. You continue using your nasal corticosteroid spray alongside it. Dupixent isn’t a replacement for topical treatments; it’s designed to work on top of them.
Most patients begin noticing improvements in congestion and breathing within the first few weeks, though the full benefit on polyp size and smell tends to build over several months. The clinical trial data at 24 weeks showed strong results, and those benefits were maintained at 52 weeks, suggesting that continued use keeps the inflammation suppressed. If you stop treatment, polyps can regrow, because Dupixent controls the underlying inflammation rather than curing it permanently.
Cost and Financial Assistance
Dupixent is expensive. The list price for a year of treatment runs into tens of thousands of dollars. For commercially insured patients, the manufacturer offers a copay assistance program (MyWay) with a maximum annual benefit of $13,000, which can bring out-of-pocket costs down significantly. Coverage varies by insurance plan, and many insurers require documentation of prior treatment failures before approving the medication. If you’re considering Dupixent, expect a prior authorization process where your doctor submits evidence that other treatments haven’t worked.