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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 allergies and inflammation.

Quick summary

["Eosinophil levels can signal allergic reactions, infections, or other health conditions."]

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

Key facts at a glance

LOINC
68402-7
Short code
Eosinophil # Vitf Manual
Synonyms
Eosinophil # Vitf Manual
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
manual-count
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order this test to check for conditions like allergies, asthma, parasitic infections, or other inflammatory or immune-related disorders. It can also help monitor treatment progress for certain conditions.

What Does a High or Low Eosinophil Count Mean?

Elevated eosinophil counts may indicate allergies, asthma, parasitic infections, or certain autoimmune diseases. Low eosinophil counts are less common and may suggest immune system suppression or certain blood disorders.

How Is the Test Performed?

A small blood sample is taken from a vein, usually in your arm. The blood is then analyzed in a lab to count eosinophils.

What Are Common Causes of Abnormal Results?

High eosinophil levels can be caused by allergies, asthma, parasitic infections, certain cancers, or other inflammatory conditions. Low levels may occur due to immune system issues or medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Eosinophil Blood Test

Frequently asked questions

What should I expect before the test?
You can eat and drink normally before the test. Avoid heavy exercise or stress, as these may temporarily affect white blood cell counts. Inform your doctor about any medications you’re taking, especially blood thinners or steroids.
How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on your lab. Your doctor will discuss the findings with you during your follow-up visit.
Can I fast before this test?
No fasting is required for this test, as it involves a simple blood draw. However, always follow your doctor’s specific instructions for your appointment.
  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