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Eosinophilia: Definition, symptoms, causes & treatment

Team AckoJan 17, 2024

Eosinophilia, a clinical term, refers to an excess of a particular type of cell in your blood called eosinophils. Read ahead for details related to Eosinophilia along with its definition, symptoms, causes, and treatment.




What are Eosinophils?

Human blood is made up of many different types of cells (functional units), each of which has a specific function. Broadly, they are classified as Red Blood Cells, White Blood Cells (WBCs). WBCs play an important role in immune function in the body. There are many types of WBCs, of which eosinophils make up a small portion. Eosinophils usually make up only 1-3% of all WBCs in circulation (maximum 5%). 

What do Eosinophils do?

Each type of white blood cell has a specific function. Eosinophils are primarily involved in dealing with:

  • Allergic reactions

  • Parasitic infections

  • Viral infections

Eosinophils play an important role in the immune processes that are involved in destroying a foreign substance in your body. They also regulate inflammation, which is the body’s response to any foreign, bad stimulus.

Eosinophils trigger inflammation, allowing the body to locate the foreign substance and eliminate it. However, sometimes your body causes an excessive inflammatory response. This ends up damaging even healthy tissue. This is the basis for conditions like Asthma and Allergic rhinitis (hay fever), where eosinophils end up playing a role in the disease process itself. 

What is Eosinophilia? 

Eosinophilia simply means an increase in the number of circulating eosinophils in your bloodstream. It is however always indicative of some underlying problem that requires investigating.

An increase in just the eosinophil cell count in the blood alone, without other clinical factors and lab findings, is a rare occurrence. Most of the time when a person is found to have Eosinophilia, it is a sign denoting some other disease process that is happening.

In these situations, the eosinophil count increases because the body requires more of these cells to specially combat the underlying cause. Broadly speaking, Eosinophilia can hence be classified into:

  • Primary Eosinophilia: This is an unusual condition where the body is unable to regulate the production of eosinophils. 

  • Secondary Eosinophilia: This is when there is a reactive increase in the number of eosinophils in the blood due to some other disease process. This is the more common type encountered in day-to-day life. 

When is a person said to have Eosinophilia?

Eosinophilia occurs when the eosinophil count in the blood is increased, between the range of 500 - 1500 cells per microlitre of blood. If the count exceeds 1500 cells per microlitre of blood over the period of several months, it is then referred to as Hypereosinophilia. There can also be an increase in the eosinophils inside a tissue, and this is referred to as Tissue Eosinophilia. This is usually seen in a tissue that is damaged or infected.

What are the causes of Eosinophilia?

The causes of Eosinophilia include:

  • Parasitic infections: Primarily those involving parasites called Helminths (worms). Examples include hookworm and roundworm (ascariasis) infections, Filarial infections, etc.

  • Fungal infections (Histoplasma and cryptococcus infections)

  • Viral diseases involving HIV and Human T-Lymphotropic virus

  • Allergic diseases like asthma, hay fever, chronic sinusitis, atopic dermatitis

  • Drug intake: Certain medications are known to cause an increase in eosinophil count, including:

    • Antibiotics like penicillin, dapsone, cephalosporins

    • Anti-seizure medications like phenytoin, carbamazepine, lamotrigine, valproate

    • HIV medications like Efavirenz and nevirapine

    • Painkillers like Ibuprofen

  • Autoimmune disorders: Lupus, rheumatoid arthritis, sarcoidosis, inflammatory bowel diseases, bullous pemphigoid, Sjogren's syndrome, etc.

  • Disorders involving the adrenal glands

  • Cancers: There are many different cancers that can produce Eosinophilia. This includes cancer of the stomach, bowels, bladder, thyroid, female reproductive structures, etc. There are also a separate group of malignant conditions which affect blood cells. These are called haematological malignancies or blood cancers. They include leukemias and lymphomas.

  • Some other rare causes include conditions like primary immunodeficiency.

  • Idiopathic HyperEosinophilia: This is a condition where no discernible cause for Eosinophilia is detected. It is characterised by elevated eosinophil counts by >1500 cells per microlitre of blood along with evidence of damage to tissues and organs like skin, heart, lungs, kidneys, sinuses, etc. It is a diagnosis of exclusion, i.e., it is diagnosed by ruling out all other possible causes. 

Symptoms of Eosinophilia

The most common causes across all the different causes of Eosinophilia include:

Organ systems most commonly affected by these conditions are the skin, lungs, and digestive tract. 

When should I see a doctor? 

Eosinophilia is usually first picked up by your doctor when evaluating you for any problem. They usually order a test called Complete Blood Count, which is a haematological evaluation of the count of all the different types of blood cells. This CBC test or a Differential Count gives you the proportion of the cells in your blood in percentage.

If the percentage of eosinophils is increased, your doctor may order a further test called Absolute Eosinophil Count which will give a more detailed understanding of the number of eosinophils in your body.

If you are told you have Eosinophilia, talk to your doctor to understand how it relates to you. You may already be suffering from some condition that is causing this. If it is showing up on your check-up, but you don't particularly have any problem, your doctor may repeat the test after a short while to see if it has cleared on its own.

They may also recommend other tests and investigations for you depending on the overall evaluation. Make sure you give them all the relevant details, including any family history of cancers, regular medicine intake, history of allergies, etc.

Determining the cause is the first step in the management of this issue. The treatment for Eosinophilia is to treat the cause. This is widely varied depending on the cause. The magnitude of treatment also involves consideration of the severity of the damage you are facing.

Talk to your doctor for more information, as this is a non-specific condition that requires probing to unearth the underlying cause. 

How to prevent Eosinophilia?

As Eosinophilia has certain triggers, the following measures can be taken for prevention:

  • Always clean fruits and vegetables thoroughly before eating to prevent parasitic infections

  • Avoid consumption of raw or undercooked meat

  • Use protective equipment such as a mask while going outdoors to avoid exposure to dust and pollen. You can also keep doors and windows shut to avoid contamination at home.

  • Take preventive medication if you have severe allergies such as hay fever.

Eosinophilia is a feature associated with several medical conditions. Hence, if your routine checkup shows you have Eosinophilia, do consult a doctor to formulate the best treatment plan.

Frequently Asked Questions (FAQs)

Here are some FAQs about Eosinophilia.


How will I know if I have Eosinophilia?

Eosinophilia can only be confirmed by blood tests. However, if you frequently suffer from allergies or have a worm infection/infestation, you may have Eosinophilia.

What is the best treatment for Eosinophilia?

There is no fixed treatment for Eosinophilia. The treatment plan depends upon the cause of the increase in the cell count.

How long does it take to cure Eosinophilia?

Depending on the underlying cause, it would take around 8-12 weeks to control Eosinophilia. If you have allergies, you may face a repeated increase in eosinophil count.

Disclaimer: The content on this page is generic and shared only for informational and explanatory purposes. Please consult a doctor before making any health-related decisions.


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