Can adalimumab cause eosinophilia?

Can Adalimumab Cause Eosinophilia?

Yes, adalimumab can cause eosinophilia, though it is a rare adverse reaction that is not listed in standard product information.

Evidence Base

The evidence for adalimumab-induced eosinophilia comes primarily from case reports and small case series rather than large clinical trials. A 2025 case report documented a patient with psoriasis and psoriatic arthritis who developed marked asymptomatic eosinophilia (peripheral blood eosinophil percentage increasing from 3.2% to 19.9%) after eight doses of biosimilar adalimumab 1. The eosinophilia resolved after discontinuation of the medication, with alternative causes (parasitic infection, allergy, hematologic disease) excluded.

A 2017 case series described a patient with rheumatoid arthritis who developed eosinophilia with skin symptoms during treatment with multiple TNF-alpha inhibitors including adalimumab 2. The mechanism appears related to immunogenicity, as biologic-specific antibodies were detected. Notably, switching to golimumab (a biologic with lower immunogenicity) resolved the eosinophilia.

A 2016 study specifically evaluating eosinophil counts in psoriasis patients treated with adalimumab confirmed that eosinophilia remains a rare adverse reaction during TNF-alpha antagonist therapy 3.

Clinical Context and Mechanism

The proposed mechanism involves immunogenicity and antibody formation against the biologic agent 2. This is consistent with the FDA drug label data showing that anti-adalimumab antibodies develop in a subset of patients 4. The eosinophilia appears to represent a paradoxical immune-mediated complication rather than a direct pharmacologic effect.

Importantly, the 2022 British Society of Gastroenterology guidelines note that anti-TNF therapies (including adalimumab) are not recommended for management of eosinophilic esophagitis 5, which is an eosinophil-driven condition. This guideline statement, while addressing a different clinical question, underscores that TNF-alpha inhibitors do not therapeutically suppress eosinophils and may paradoxically be associated with eosinophilic complications.

Clinical Characteristics

When adalimumab-induced eosinophilia occurs, it typically presents as:

• Asymptomatic elevation in most cases 1
• Peripheral blood eosinophilia that can be marked (up to 19.9% of white blood cells)
• Potential association with skin symptoms (rash, dermatitis) 2
• Reversibility upon drug discontinuation 1

Practical Management Algorithm

If eosinophilia is detected during adalimumab therapy:

1. Assess for symptoms: Look specifically for skin manifestations (rash, urticaria, psoriasiform dermatitis), gastrointestinal symptoms (abdominal pain, diarrhea), respiratory symptoms (dyspnea, cough), or systemic symptoms (fever, weight loss)

2. Exclude alternative causes systematically:

   • Parasitic infections (stool ova and parasites, serologies for endemic parasites)
   • Allergic conditions (medication review, environmental exposures)
   • Hematologic disorders (peripheral smear, bone marrow evaluation if indicated)
   • Organ involvement (chest imaging, cardiac evaluation if symptomatic)

3. Determine severity:

   • Mild: >500 cells/μL
   • Moderate: >1500 cells/μL
   • Severe: >5000 cells/μL

4. Management based on clinical presentation:

   • Asymptomatic mild-moderate eosinophilia: Continue adalimumab with close monitoring (repeat CBC every 4-8 weeks)
   • Symptomatic eosinophilia or severe elevation: Discontinue adalimumab
   • Persistent eosinophilia after discontinuation: Consider switching to a TNF-alpha inhibitor with lower immunogenicity (e.g., golimumab) 2

Important Caveats

• Routine monitoring for eosinophilia is not standard practice based on current guidelines 6. The 2012 American College of Chest Physicians guidelines for adalimumab monitoring do not include routine eosinophil count surveillance 6

• The incidence is very low, making universal screening impractical and not cost-effective

• Most cases resolve spontaneously after drug discontinuation without long-term sequelae 1

• Do not confuse with dupilumab-associated eosinophilia, which is a distinct and more common phenomenon with different mechanisms 7, 8

• Consider checking anti-adalimumab antibodies if eosinophilia develops, as this may guide switching decisions 2