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  • Cynthia M. Johnson, MA
Publication Type:




Eosinophilia is a higher than normal number of eosinophils. Eosinophils are a type of white blood cell. They help protect the body from certain types of infections. They are also involved in allergic reactions.

White Blood Cells.

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Eosinophilia may be caused by:

  • Problems in genes that control cell growth
  • A change in the number of cells due to certain cancers
  • Health problems, such as infections, problems with the immune system, or allergies

Risk Factors

Eosinophilia is more common in people who have family members with it.

Other things that may raise the risk are:

  • Allergies, including food allergies
  • Infections, mainly those caused by parasites
  • Inflammatory conditions
  • Skin problems
  • Certain blood cancers
  • Reactions to medicines
  • Exposure to certain toxins


Some people may not have symptoms. The symptoms a person will have depend on what is causing the eosinophilia. For example:


The doctor will ask about symptoms and past health. A physical exam may be done.

Initial tests may be:

  • Blood tests
  • Stool tests
  • Biopsy
  • Bone marrow tests

Other tests may be done, depending on the problems the person is having. They may include:


The goal is to treat the underlying cause of the eosinophilia. Corticosteroids may be given to ease inflammation. This will also lower the number of eosinophils.


There are no known guidelines to prevent eosinophilia.





  • Eosinophilia. Cleveland Clinic website. Available at:https://my.clevelandclinic.org/health/diseases/17710-eosinophilia.
  • Eosinophilia. Merck Manual Professional Version website. Available at: https://www.merckmanuals.com/professional/hematology-and-oncology/eosinophilic-disorders/eosinophilia.
  • Eosinophilia—approach to the patient. EBSCO DynaMed website. Available at: https://www.dynamed.com/approach-to/eosinophilia-approach-to-the-patient.
  • World Health Organization (WHO) 2017 update on diagnosis, risk stratification, and management of WHO-defined eosinophilic disorders can be found in Am J Hematol 2017 Nov;92(11):1243.


  • Daniel A. Ostrovsky, MD
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.