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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

["Eosinophils help protect your body from harmful substances and infections."]

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

Key facts at a glance

LOINC
26450-7
Short code
Eosinophil NFr Bld
Synonyms
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 Is Done

Your doctor may order this test to diagnose or monitor conditions such as allergies, asthma, parasitic infections, certain types of cancer (like leukemia), or other inflammatory or immune-related disorders. It can also help assess how your body is responding to treatments for these conditions.

What to Expect Before the Test

No special preparation is needed for this test. You may have a small needle inserted into your arm to draw blood, similar to other blood tests. If you’re on blood-thinning medication, let your doctor know before the test.

What Happens During the Test

Blood is collected from a vein in your arm using a needle. The blood sample is then sent to a lab for analysis. The process usually takes a few minutes, and you may feel a brief pinch or slight discomfort.

What the Results Mean

Results are typically reported as the number of eosinophils per microliter (µL) of blood. Elevated levels may suggest allergies, infections, or other underlying conditions, while very low levels might indicate immune system issues or certain medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Eosinophil Blood Test

Frequently asked questions

How long does it take to get my eosinophil test results?
Results are usually available within 1 to 3 business days, depending on your lab’s processing time. Your doctor will contact you once they are ready to review them with you.
Can I eat or drink before this test?
You can eat and drink normally before this test, as no special diet or fasting is required.
Is there any pain or discomfort during the blood draw?
Most people experience only mild discomfort or a brief pinch during the blood draw. Some may feel a small bruise or swelling at the site, but this usually goes away quickly.
  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