What does a Eosinophils test measure?

A eosinophils test measures the number of eosinophil white blood cells in your blood, which are part of your immune system's inflammatory response. These cells can help identify your body's response to infection, allergic reactions, and certain inflammatory conditions. The measurement is expressed in units of 10⁹/L (billion cells per litre of blood).

What is a normal Eosinophils level?

Normal eosinophil levels typically range from 0–0.4 × 10⁹/L, though reference ranges may vary slightly depending on age, sex, and individual laboratory standards. To understand what your specific result means for your health, it's important to discuss your results with your healthcare provider, who can interpret them in the context of your individual circumstances.

When should I consider getting a Eosinophils test?

You may want to consider a eosinophils test if you experience symptoms such as persistent allergies, asthma, unexplained skin rashes, or recurrent infections, or if your healthcare provider recommends screening as part of routine health monitoring. Testing may also be useful if you have a family history of allergic or autoimmune conditions, or as part of investigating any unusual immune system activity. Discuss with your healthcare provider about whether testing is appropriate for your individual situation.

Is Eosinophils included in Listen Health's membership?

Yes, eosinophils testing is included as part of Listen Health's comprehensive panel of over 100 biomarkers available in both Standard and Premium annual memberships. This allows you to monitor your immune function alongside other important health markers as part of your preventative health strategy.

Eosinophils — What It Is & Why It Matters | Listen Health

Name: Eosinophils
Creator: Listen Health
Published: 2026-03-15

Do I need a Eosinophils test?

Do you find yourself dealing with persistent allergies, unexplained inflammation, or frequent infections? Your eosinophils might be trying to tell you something important about what's happening beneath the surface.

Eosinophils are a type of white blood cell that plays a key role in fighting certain infections and managing allergic responses, and testing this biomarker reflects how your immune system may be responding to various triggers in your environment and body.

Understanding your eosinophil levels can help you and your healthcare provider identify potential allergic reactions, parasitic infections, or inflammatory conditions that might be affecting your wellbeing. When you see your results as part of Listen Health's immune function panel, you'll have clearer insight into your body's defence mechanisms and can make more informed decisions about your health moving forward.

Eosinophils — Key Facts

MeasuresFight inflammation, infection, and allergic responses.

CategoryImmune Function

Unit10⁹/L

Tested inListen Health Standard & Premium membership (100+ biomarkers)

Reviewed byDr Jamie Deans, MBChB

What is it?

Eosinophils are a type of white blood cell found in your blood and tissues. They are part of your immune system and help fight off certain infections, especially parasites, and are involved in allergic reactions. Eosinophils are produced in the bone marrow and travel through the bloodstream to different tissues, where they help regulate inflammation, tissue repair, and immune responses. They release proteins and chemicals that can destroy invaders like parasites, but can also cause tissue damage if too many are present or if they are overactive.

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Why does it matter?

Eosinophils play a double role in health: they help defend against infections and keep tissues healthy, but can also cause problems if their numbers are too high or too low. High eosinophil percentages (eosinophilia) can be a sign of allergies (like asthma, hay fever, or eczema), certain infections (especially parasites), autoimmune diseases, or rare blood disorders. Chronic high eosinophil levels can lead to tissue damage in organs such as the lungs, skin, gut, or heart, and may require further testing to find the cause. Low eosinophil percentages are less common and usually not a problem, but can occur with some infections, stress, or after taking certain medications

What causes fluctuations?

Allergic reactions: Hay fever, asthma, eczema, or food allergies.
Parasitic infections: Especially intestinal worms or protozoa.
Autoimmune diseases: Conditions such as lupus or vasculitis.
Medications: Certain antibiotics, anti-inflammatories, or immune therapies can raise eosinophil counts.

References

Wechsler, M. E., Munitz, A., Ackerman, S. J., et al. (2021). Eosinophils in health and disease: A state-of-the-art review. Mayo Clinic Proceedings, 96(10), 2694–2707. https://doi.org/10.1016/j.mayocp.2021.04.025
Kanda, A., Yasutaka, Y., Van Bui, D., et al. (2020). Multiple biological aspects of eosinophils in host defense, eosinophil-associated diseases, immunoregulation, and homeostasis: Is their role beneficial, detrimental, regulator, or bystander? Biological & Pharmaceutical Bulletin, 43(1), 20–30. https://doi.org/10.1248/bpb.b19-00892
Rodrigo-Muñoz, J. M., Gil-Martínez, M., Sastre, B., & Del Pozo, V. (2021). Emerging evidence for pleiotropism of eosinophils. International Journal of Molecular Sciences, 22(13), 7075. https://doi.org/10.3390/ijms22137075
Jesenak, M., Diamant, Z., Simon, D., et al. (2023). Eosinophils—from cradle to grave: An EAACI task force paper on new molecular insights and clinical functions of eosinophils and the clinical effects of targeted eosinophil depletion. Allergy, 78(12), 3077–3102. https://doi.org/10.1111/all.15884
Thomsen, G. N., Christoffersen, M. N., Lindegaard, H. M., et al. (2023). The multidisciplinary approach to eosinophilia. Frontiers in Oncology, 13, 1193730. https://doi.org/10.3389/fonc.2023.1193730
Kita, H. (2011). Eosinophils: Multifaceted biological properties and roles in health and disease. Immunological Reviews, 242(1), 161–177. https://doi.org/10.1111/j.1600-065X.2011.01026.x
Jackson, D. J., Akuthota, P., & Roufosse, F. (2022). Eosinophils and eosinophilic immune dysfunction in health and disease. European Respiratory Review, 31(163), 210150. https://doi.org/10.1183/16000617.0150-2021
Ramirez, G. A., Yacoub, M. R., Ripa, M., et al. (2018). Eosinophils from physiology to disease: A comprehensive review. BioMed Research International, 2018, 9095275. https://doi.org/10.1155/2018/9095275
Day, K. S., Rempel, L., Rossi, F. M. V., & Theret, M. (2024). Origins and functions of eosinophils in two non-mucosal tissues. Frontiers in Immunology, 15, 1368142. https://doi.org/10.3389/fimmu.2024.1368142
Sturm, E. M., Knuplez, E., & Marsche, G. (2021). Role of short-chain fatty acids and apolipoproteins in the regulation of eosinophilia-associated diseases. International Journal of Molecular Sciences, 22(9), 4377. https://doi.org/10.3390/ijms22094377
Hogan, S. P., Rosenberg, H. F., Moqbel, R., et al. (2008). Eosinophils: Biological properties and role in health and disease. Clinical and Experimental Allergy, 38(5), 709–750. https://doi.org/10.1111/j.1365-2222.2008.02958.x
Liao, W., Long, H., Chang, C. C., & Lu, Q. (2016). The eosinophil in health and disease: From bench to bedside and back. Clinical Reviews in Allergy & Immunology, 50(2), 125–139. https://doi.org/10.1007/s12016-015-8507-6

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AHPRA Disclaimer: This information is general in nature and should not replace individual medical advice. Always discuss your test results and health concerns with a registered healthcare practitioner.