Dupixent Long-Term Safety Data: What We Know and Don't Know

Medically reviewed by licensed healthcare professionals · Legally reviewed by mass tort litigation specialists · Last updated: March 2026

Dupixent is intended for long-term, chronic use. While short-term safety was established in the original clinical trials, understanding the risks of years or decades of use requires ongoing study. As of 2026, we have nearly a decade of data, which provides some answers and highlights remaining questions.

What the Long-Term Extension (LTE) Studies Show

The original randomized controlled trials (RCTs) for Dupixent typically lasted for one year. Patients who completed these trials were often eligible to enroll in open-label long-term extension (LTE) studies, where they continued to receive the drug and were monitored for safety and efficacy. These LTE studies provide the best available data on the safety of continuous Dupixent use over several years.

A 5-year LTE study of adults with atopic dermatitis, published in 2024, found that:

• The efficacy of Dupixent was maintained over the 5-year period.
• No new safety signals emerged. The types of adverse events reported were consistent with what was seen in the first year of treatment.
• The most common adverse events remained conjunctivitis, injection site reactions, and nasopharyngitis (common cold).
• The incidence of serious infections was low and did not increase over time.

Similar LTE studies for asthma and other indications have shown a comparable long-term safety profile. Overall, the data from these manufacturer-sponsored studies suggests that the known risks of Dupixent do not appear to increase with longer duration of use, at least up to five years.

What We Still Don't Know: Unanswered Questions

Malignancy Risk: The immune system plays a critical role in cancer surveillance — identifying and destroying abnormal cells before they become tumors. Any drug that modulates the immune system over the long term carries a theoretical risk of affecting cancer rates. The 5-year LTE studies did not show a statistically significant increase in cancer, but these studies are not large enough or long enough to definitively rule out a small increase in risk for certain types of cancer. This will require larger registry studies and many more years of data.

Cardiovascular Risk: Chronic inflammation is a known risk factor for cardiovascular disease. By reducing systemic type 2 inflammation, it is biologically plausible that Dupixent could have a long-term beneficial effect on cardiovascular health. Conversely, by potentially shifting immune pathways, it could have unforeseen effects. The long-term impact on cardiovascular events like heart attack and stroke is not yet known and is an area of active study.

Autoimmune Disease Risk: As with arthralgia, there is a theoretical risk that long-term suppression of the type 2 immune pathway could lead to the development of other autoimmune conditions in susceptible individuals. Current data has not confirmed this risk, but it remains a long-term monitoring priority.

Use in Pregnancy and Children: While Dupixent is approved for children as young as 6 months for certain conditions, the long-term effects of modulating the immune system during critical developmental periods are not fully understood. Data on pregnancy outcomes is also still being collected through registries.

The Role of Post-Market Surveillance

Because clinical trials are limited in size and duration, the FDA relies on the FDA Adverse Event Reporting System (FAERS) to detect rare or long-term side effects after a drug is on the market. Any patient or doctor can submit a report to FAERS. This "real-world" data is what often identifies safety signals that were not apparent in the original trials. Legal claims based on drug side effects often rely on evidence that emerges from FAERS years after a drug's approval.