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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 certain infections and respond to allergic reactions.

Quick summary

["Eosinophils help your body defend against parasites and allergies, and elevated levels may signal underlying conditions."]

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

Key facts at a glance

LOINC
34913-4
Short code
Imm Eosinophil NFr Bld
Synonyms
Imm Eosinophil NFr Bld
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like persistent itching, skin rashes, asthma, or unexplained allergic reactions. It could also be used to monitor conditions like parasitic infections, certain cancers, or allergic disorders.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm or hand to draw a small amount of blood. The process takes a few minutes, and you may feel a slight pinch.

What the Results Mean

Results are typically reported as the number of eosinophils per microliter (µL) of blood. High levels (above normal) may indicate allergies, infections, or other health issues. Low levels may suggest immune system problems or certain medications.

Common Conditions Linked to Eosinophil Levels

Elevated eosinophil counts can be linked to conditions like asthma, allergic reactions, parasitic infections, certain cancers (e.g., lymphoma), or autoimmune diseases. Low levels might be associated with infections, immune deficiencies, or medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Eosinophils Serve Multiple Roles

Short name

Eosinophil blood count

Frequently asked questions

What causes my eosinophil count to be higher than usual?
Higher-than-normal eosinophil counts can result from allergies, asthma, parasitic infections, certain cancers, or inflammatory conditions. Your provider may also investigate if you have unexplained symptoms like persistent itching, skin rashes, or fatigue.
Can I eat or drink anything before this test?
No dietary restrictions apply. You can eat, drink water, and take medications as usual unless your provider advises otherwise.
How long will it take to get my results?
Results are usually available within 1 to 3 business days, depending on your lab’s processing time. Your healthcare provider will discuss them with you during your follow-up visit.
  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