Eosinophil levels rise and fall depending on how your immune system responds to inflammation, infection, or allergens. Elevated levels — known as eosinophilia — can be triggered by allergic reactions (like hay fever, asthma, eczema, or medication for allergies), parasitic infections (especially worm-related), autoimmune diseases such as vasculitis or rheumatoid arthritis, and certain cancers, including Hodgkin lymphoma or eosinophilic leukemia. Other causes include drug hypersensitivity syndromes like DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms), adrenal insufficiency (Addison’s disease), and skin disorders such as dermatitis herpetiformis or pemphigus.
On the other hand, low eosinophil levels — called eosinopenia — are often linked to acute bacterial or viral infections, stress, trauma, or the use of corticosteroids, which suppress immune activity. High cortisol levels, as seen in Cushing’s syndrome, can also lower eosinophil counts. While minor illnesses or short-term stress usually don’t cause lasting changes, various external and internal factors can influence test results. Understanding these can help make sense of fluctuations in your eosinophil count and guide next steps with your healthcare provider.
• Typically 0–500 cells/µL or 0–5 percent white blood cells, though each lab may have slightly different ranges.
• Below you’ll find a bit more information about eosinophil results:
• Normal (0–500 cells/µL). Normal immune balance — no concern.
• Mildly elevated (500–1,500 cells/µL). Mild eosinophilia — may be linked to allergic rhinitis, asthma, eczema, medication reactions, or early parasitic infections.
• Moderate (1,500–5,000 cells/µL). Moderate eosinophilia — may occur with chronic allergies, some parasitic infections, or autoimmune diseases.
• Severe (>5,000 cells/µL). Hypereosinophilia — may result from parasitic infections, vasculitis (eosinophilic granulomatosis with polyangiitis, EGPA), or certain blood cancers.
• Low or absent (<0.05%). Usually not concerning — may happen temporarily after stress, steroid use, or acute infection.
No. An eosinophil count requires a blood draw that must be performed by a healthcare professional in a lab setting.
Yes. An eosinophil test is usually covered by insurance when it’s ordered for a medical reason — for example, to evaluate allergies, asthma, infection, or inflammation. Coverage can vary depending on your plan. Insurance is not required for lab testing through Hers.
It may indicate allergies, asthma, parasitic infection, or — in rare cases — a blood disorder. Your provider will interpret this with other results.
Yes. Corticosteroids, certain antibiotics, or anti-seizure drugs can increase or decrease eosinophil counts.
Yes. Acute stress or illness can temporarily suppress eosinophil counts.
• Complete blood count (CBC) with differential
• Allergy testing (IgE panel)
• Stool ova and parasite test
• Autoimmune and inflammatory markers
• Bone marrow biopsy or flow cytometry
