Eosinophils in a Blood Test: Normal Range & High Levels
Eosinophils are a type of white blood cell that helps fight parasites and drives allergic and inflammatory responses. They're counted as part of a complete blood count (CBC) with differential. A normal absolute eosinophil count is roughly 30–350 cells per microliter (or 0–5% of white blood cells); a high count often points to allergies, asthma, or parasitic infection.
Also known as: Absolute eosinophils, eos blood test, eosinophil count
Eosinophils normal range
| Category | Range (cells/µL) |
|---|---|
| Normal (absolute) | 30–350 cells/µLReference ranges vary by lab |
| Normal (percentage) | 0–5% of WBCs |
| Mild elevation | 500–1,500 cells/µL |
| Marked elevation | > 1,500 cells/µLWarrants evaluation |
Reference ranges vary by laboratory. Use the range printed on your own report as the definitive comparison.
What high Eosinophils can mean
- Allergies, hay fever, or asthma
- Parasitic infections
- Eczema and other skin conditions
- Drug reactions
- Rarely, autoimmune or blood disorders
What low Eosinophils can mean
- Low eosinophils are usually not a concern
- Can occur with acute stress, infection, or steroid medication
What to do about an abnormal result
- Mildly high eosinophils are common with allergies and usually not urgent.
- Persistently high counts (over 1,500) are investigated for underlying causes.
- Interpret with the rest of your CBC and any allergy or infection symptoms.
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Frequently asked questions
What is a high eosinophil count?
An absolute eosinophil count above about 500 cells/µL is considered elevated (eosinophilia). Mild elevations are commonly caused by allergies or asthma. Counts above 1,500 cells/µL are more significant and prompt a search for parasitic, autoimmune, or blood-related causes.
Can allergies raise eosinophils?
Yes. Allergies, hay fever, asthma, and eczema are among the most common causes of a mildly elevated eosinophil count, because eosinophils are central to allergic inflammation.
Related biomarkers
See also
Sources
This page draws on the following authoritative references.
- Blood Differential — MedlinePlus
- Eosinophilia — StatPearls
Medically reviewed by Antonieta Rueda, MD and Kyle R. Toth, MD · Last reviewed July 22, 2026
This article is for informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or your lab results.