Eosinophilia: Definition, Causes, Symptoms, Treatment & Prevention

Eosinophilia: Definition, Causes, Symptoms, Treatment & Prevention

Eosinophils are white blood cells that destroy allergens or foreign substances such as parasites and aid the immune system in starting an allergic reaction. When there is a rise in eosinophils, it is called eosinophilia. Some medical conditions and medicines cause high eosinophil levels. 

Eosinophilia refers to a higher level of eosinophils in your tissue or body, a condition indicating an allergic reaction, cancer, or parasitic infection. Eosinophils are a kind of disease-fighting white blood cell made in the bone marrow, which gets transferred to different tissues.

This blog is a comprehensive understanding of eosinophilia, its causes, symptoms, treatment, and prevention.

What is eosinophilia? 

Eosinophilia is a medical condition where the eosinophil count is high. Eosinophils are one of the types of white blood cells that fight against allergens and assist in protecting the body from fungal and parasitic infections.  

The presence of eosinophils in the body plays two different roles in the immune system. These are –

  1.  Regulating inflammation: Promoting inflammation helps isolate and control disease, but it can lead to tissue damage or other complicated symptoms like asthma or allergies when it becomes excessive.
  2. Destroying foreign substances: Eosinophils can consume foreign particles in the body, which can help fight a parasitic infection.

What is the normal percentage? 

Eosinophils constitute about 0.0 to 6.0 per cent of the white blood cells, as measured in a differential count done with a blood sample. If results are not in the normal range, your doctor may suggest an absolute eosinophil count.  In a laboratory, a technician will add a special stain to your blood sample. This lets them see the eosinophils and count how many you have in every 100 cells. They will multiply that percentage by your white blood cell count to get your absolute eosinophil count. A standard absolute eosinophil count ranges from 0 – 500 cells per microliter (<0.5 x 109/L).

What are the Types of eosinophilia?

Eosinophilia can be segregated into the following two categories –

  1. Blood eosinophilia: When you have high levels of eosinophils in the blood, it may be diagnosed through a blood test, usually in the form of a complete blood count. A count exceeding 500 eosinophils per microliter of blood is considered eosinophilia in adults. A count exceeding 1500 for several months is labeled hypereosinophilia.
  2. Tissue eosinophilia: This results in excess eosinophils in tissues at the site of inflammation or infection. It may be diagnosed by taking samples of certain fluids, like mucus from the nasal tissues. If you have tissue eosinophilia, the presence of eosinophils is likely to be normal in your bloodstream.

What are the symptoms of eosinophilia?

The reason behind the elevated eosinophil count will determine the symptoms associated with eosinophilia. If the eosinophils count is mildly high, you may not experience any symptoms. However, the common symptoms include –

  • Itching
  • Asthma
  • Rash
  • Diarrhea in case of parasite infection
  • Runny nose for those with allergic problems

What is eosinophilic asthma?

Eosinophilic asthma like other types of asthma causes inflamed airways that are blocked by fluid and mucus and spasms making it difficult to breathe.

However, unlike other kinds of asthma, eosinophilic asthma has abnormally high levels of a specific type of white blood cell called eosinophils.

Most often, this form of asthma develops in those between the ages of 25 and 35. Usually, individuals with eosinophilic asthma do not suffer from allergies. Eosinophilic asthma can be difficult to treat and may have a detrimental effect on an person’s quality of life.

When to consult a doctor?

Eosinophilia is mainly detected when your doctor prescribes any blood test to diagnose any health issue you are currently experiencing. Although it is not an unexpected finding, it is sometimes discovered by chance.

Any evidence of tissue or blood eosinophilia may be advised for further testing to determine the severity of the illness and the underlying cause behind such an occurrence.

If the diagnosis is accurate and you receive proper treatment on time, your eosinophilia problem is likely to get resolved quickly. In the case of hypereosinophilic syndrome, your physician may prescribe corticosteroids. But constant monitoring is required to keep a check on the effectiveness of the treatment. The cause of eosinophilia can vary and it is always good to seek medical care from an expert and learn more about the cause of the eosinophilia.

What is Eosinophilia–myalgia syndrome? 

Eosinophilia-myalgia syndrome (EMS) is a rare condition that leads inflammation in different body parts including lungs, skin, lungs and muscles. EMS causes high levels of white blood cells known as eosinophils. These eosinophils build up within the body and can cause serious complications.

What are the causes of eosinophilia?

The eosinophil counts in the blood increase due to many health conditions. Some of them include:

Among these, allergic reactions and parasitic diseases are among the common causes of eosinophilia.

Specific diseases can also result in tissue or blood eosinophilia such as –

What are the available treatment options for eosinophilia?

Doctors treat the underlying condition or issue leading to increased eosinophil counts. For instance, doctors prescribe steroids or other medications for patients suffering from  eosinophilic esophagitis. If people have high eosinophil levels due to allergies or chronic sinusitis, the doctor can suggest allergy testing to find the causes of the allergic reaction that has triggered eosinophilia. If a medication is causing eosinophilia, the doctor may typically suggest stopping the medication. The doctor will treat the infection or cancer if that is the cause of eosinophilia.

Like the type of diagnostic test recommended by the physician, the treatment will also be determined by eosinophilia. The various treatment options include –

  • Constant monitoring in case of mild eosinophilia with repeat lab tests to determine the level.
  •  If any specific medicine is causing your eosinophil levels to fluctuate, it might be advised to discontinue it.
  • Stepping up the therapies for eczema, allergies, and asthma.
  • Anti-parasitic treatment for parasite infections.
  • Steroids like prednisone may be recommended for treating hypereosinophilic syndromes.

How to prevent eosinophilia?

Allergy-related eosinophilia is preventable with the help of treatment to control the body’s allergic reactions. However, there are occasions when eosinophilia can be a sign of an underlying condition that may not be preventable.

Certain precautionary measures can help to reduce the incidence of eosinophilia, including –

  • Maintaining proper physical hygiene.
  • Avoiding uncooked meat, fish, freshwater prawns, snails, slugs, etc.
  • Washing fruits and vegetables properly to avoid parasites.
  • Avoiding certain medications that you are allergic to.
  • Living in a dust-free and clean environment.

A general preventive measure is to avoid allergens that are known to trigger eosinophilia.


Once the underlying cause of eosinophilia is detected, the doctor will treat the condition responsible for such an occurrence. You will probably be given several tests to help make a proper diagnosis. In some cases, diagnosis and treatment may be required to be carried out by a specialist. Make sure to discuss your present condition with your doctor and other additional complications that might trigger such a problem.

Eosinophilia occurs means an abnormally high number of eosinophils in the body. Most people learn that they have eosinophilia when undergoing routine blood tests. A high eosinophil count is usually not a cause for concern. The doctor can order additional tests to discover the causes of excessive eosinophils. 

Frequently Asked Questions (FAQs):

Why do I need an eosinophil count?

The eosinophil or white blood cell count changes can help determine whether you have eosinophilia and its severity. Performing a white blood count differential testing will help your doctor find any white blood count abnormalities. Simultaneously, a complete differential blood count test will help determine the percentage of each white blood cell present in the body.

How can I reduce my eosinophil count?

Among the current therapies to reduce eosinophil count, Glucocorticosteroids are the most effective therapy for reducing eosinophil count in the blood and tissue. However, the effects of corticosteroids on the system can lead to potentially harmful side effects, limiting therapeutic use.

Which is the best food for eosinophilia?

For patients with eosinophilia, the six-food elimination diet (DFED) is the most frequently prescribed dietary therapy. The diet typically follows the exclusion of eggs, soy, nuts, fish, milk, shellfish, and wheat

What can people expect if they suffer from eosinophilia? 

People with high eosinophil levels may require treatment for the underlying condition that may cause their eosinophil levels to increase.  

How is eosinophilia diagnosed?  

Doctors diagnose eosinophilia with a complete blood count (CBC) with a differential white blood cell count and an absolute eosinophil count. Depending on the individual’s situation, the doctor may perform additional tests to find the causes of the high eosinophil levels.