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Eosinophil Count (Peripheral Blood)

Published: August 9, 2026Updated: August 16, 2026

This test measures the number of eosinophils, a type of white blood cell, in your blood. Eosinophils help fight infections caused by parasites and play a role in allergic reactions.

Quick summary

["Eosinophil levels help diagnose and monitor conditions like allergies, asthma, or certain infections."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
48049-1
Short code
Eosinophil Stl Ql Wright Stn
Synonyms
Eosinophil Stl Ql Wright Stn
Category
chemistry
Sample
stool
Container
Clean container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
wright-stain
Specimen volume
5 g
Stability
Refrigerated: 24h, Frozen: 7d
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order this test to check for infections, allergies, or inflammatory conditions. High levels might suggest parasitic infections, allergies, or certain autoimmune diseases, while low levels could indicate immune suppression or other health issues.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm, and a few drops of blood will be drawn into a test tube or vial. The process usually takes just a few minutes.

What the Results Mean

Results are typically reported as the number of eosinophils per microliter (µL) of blood. While reference ranges vary by lab, abnormal counts may signal underlying conditions that need further evaluation.

Common Conditions Linked to Eosinophil Levels

Elevated eosinophils can be linked to conditions like asthma, allergic reactions, parasitic infections, or certain cancers. Low eosinophil counts may indicate conditions like HIV, chemotherapy side effects, or other immune disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Eosinophil CBC

Frequently asked questions

What causes eosinophils to rise?
Eosinophils can increase due to allergies, asthma, parasitic infections, certain cancers (like Hodgkin lymphoma), or inflammatory conditions. Stress, medications, or other immune responses can also temporarily raise levels.
What does it mean if my eosinophil count is high?
A high eosinophil count may signal an allergic reaction, infection, or inflammatory process. Your doctor will review your symptoms and other test results to determine the cause and recommend treatment if needed.
Can diet or lifestyle affect eosinophil counts?
Diet and lifestyle factors like stress, certain foods, or allergens may influence eosinophil levels temporarily. However, they are not the primary cause of abnormal counts, which usually require medical evaluation.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy