Does Dupixent (dupilumab) affect white blood cell counts in patients with a history of allergic reactions or immune system dysregulation?

Does Dupixent Lower White Blood Cells?

No, Dupixent (dupilumab) does not lower white blood cells; in fact, it typically causes a transient increase in eosinophils (a type of white blood cell), though this is rarely clinically significant and does not require routine laboratory monitoring. 1, 2, 3

Effect on White Blood Cell Counts

Eosinophil Changes (Most Common)

• Dupilumab causes transient increases in blood eosinophil counts, not decreases, particularly in patients with atopic dermatitis, asthma, and chronic rhinosinusitis with nasal polyps 1, 3
• In atopic dermatitis patients, mean eosinophil increases from baseline to Week 4 ranged from 100 cells/mcL (median 0) in adults to 478 cells/mcL (median 90) in children under 6 years 1
• In asthma patients, mean increases were 130 cells/mcL (median 10) at Week 4, followed by decline starting by Week 24 to baseline or lower levels 1, 3
• These increases are transient and typically resolve without intervention, with counts declining back to baseline or below by Week 24 3

Clinical Significance of Eosinophil Changes

• Treatment-emergent eosinophilia (≥500 cells/mcL) occurred at similar rates between dupilumab and placebo groups across most indications 1
• Treatment-emergent eosinophilia (≥5,000 cells/mcL) was observed in <3% of dupilumab-treated subjects and <0.5% in placebo recipients 1
• Clinical symptoms associated with increased eosinophils were rare, occurring in only 7 of 4,666 dupilumab-treated patients (including 6 cases of eosinophilic granulomatosis with polyangiitis), and only in asthma or chronic rhinosinusitis patients 3
• Eosinophilia was not associated with reduced dupilumab efficacy 3

No Routine Laboratory Monitoring Required

• Analysis of three phase III trials demonstrated no clinically important changes in blood cell counts, blood chemistry, or urine chemistry that could be linked to dupilumab 2
• Dupilumab does not require routine laboratory testing for blood counts, unlike traditional immunosuppressants such as cyclosporine, azathioprine, or methotrexate 4, 2
• The FDA label for dupilumab does not mandate baseline or ongoing complete blood count monitoring 1

Comparison to Other Systemic Therapies

Traditional Immunosuppressants That DO Lower White Blood Cells

• Azathioprine requires monitoring for hematologic abnormalities and necessitates regular CBC testing 4
• Cyclosporine requires CBC monitoring along with comprehensive metabolic panels 4
• Methotrexate can cause hematologic abnormalities requiring regular CBC monitoring 4
• Mycophenolate requires CBC monitoring for potential hematologic effects 4

Dupilumab's Unique Safety Profile

• Dupilumab has no monitoring requirements listed in the FDA label, unlike the immunosuppressants above 4
• The most common adverse events are injection site reactions, upper respiratory tract infections, and ocular complications—not hematologic abnormalities 1

Important Clinical Considerations

When to Monitor Eosinophils

• Routine eosinophil monitoring is not necessary for most patients on dupilumab 2
• Consider monitoring if patients develop symptoms suggestive of hypereosinophilic syndromes (rare), particularly in asthma or chronic rhinosinusitis patients 3
• Physicians should base judgment on individual patient history and baseline eosinophil counts, remaining alert to hypereosinophilic symptoms 3

Recent Lymphoma Signal (Context for Immune Concerns)

• A 2025 population-based cohort study found dupilumab treatment in asthma patients was associated with increased risk of lymphoma (HR=1.79), particularly T and NK cell lymphomas (HR=4.58), though all-cause mortality was significantly lower (HR=0.65) 5
• This finding highlights the need for long-term surveillance but does not relate to white blood cell count reductions 5

Common Pitfalls to Avoid

• Do not order routine CBCs for dupilumab monitoring as you would for traditional immunosuppressants—this is unnecessary and not evidence-based 2
• Do not discontinue dupilumab solely due to asymptomatic eosinophilia, as this is expected and rarely clinically significant 3
• Do not confuse eosinophil increases with immunosuppression—dupilumab is not a traditional immunosuppressant and does not cause the hematologic toxicity seen with agents like azathioprine or methotrexate 4, 2