Basophilia refers to when there are too many basophils in a person’s blood. Basophils are a type of white blood cell.

Basophilia is not a condition on its own but can be an important marker of other underlying medical problems.

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Basophilia generally indicates the existence of another underlying medical condition.

In healthy individuals, basophils account for a minimal amount of the body’s cell population. However, people with basophilia have an abnormally high amount of basophils.

Basophils are a type of white blood cell produced in the bone marrow. White blood cells help the body fight infections.

A high level of white blood cells can indicate an immune response in the body, which protects the body from infections and other problems. However, when a person has basophilia, the increase in white blood cells may be due to more serious causes.

Basophilia rarely exists independently and most often indicates the presence of another condition.

The most common causes of basophilia include:

  • infections
  • allergies
  • disorders and diseases characterized by chronic inflammation
  • myeloproliferative disorders


Infections often trigger an inflammatory response in the body, which may make a person more likely to develop basophilia.

However, developing basophilia as a result of an acute infection or illness is rare. Certain diseases, including chicken pox and tuberculosis, may make a person more likely to develop basophilia.


Allergies and allergic reactions to foods and drugs can cause basophilia. The severity of the allergy or the response may correlate with the severity of the basophilia.

Chronic inflammation

Many disorders and diseases are directly related to chronic inflammation. A person with a condition characterized by inflammation may be more likely to develop basophilia.

Conditions that cause chronic inflammation include:

Myeloproliferative disorders

Myeloproliferative disorders cause the bone marrow to overproduce different types of blood cells including basophils.

Myeloproliferative disorders that can cause basophilia include the following:

  • essential thrombocythemia
  • chronic myelogenous leukemia
  • polycythemia vera
  • primary myelofibrosis
  • systemic mastocytosis
  • hypereosinophilic syndrome
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The symptoms of basophilia vary but may include fatigue, abdominal pain, and cramping.

An abnormally high amount of basophils can cause a variety of non-specific symptoms.

Basophilia may cause:

  • abdominal pain and cramping
  • itching
  • unexplained weight loss
  • fatigue
  • fever
  • malaise or general feelings of being unwell

However, the symptoms a person with basophilia experiences will vary depending on their underlying medical condition.

People that have basophilia due to an infection will have symptoms of the infection, which may include fever, fatigue, and malaise.

A person with basophilia as a result of allergies will have typical allergy symptoms, including:

  • sneezing
  • runny or stuffy nose
  • itchy eyes
  • rash or hives
  • wheezing
  • swelling

A person who has basophilia as a result of IBD may experience:

  • abdominal cramping
  • diarrhea
  • bleeding from rectum
  • pain in the rectal area

Basophilia caused by a condition that causes chronic inflammation may cause symptoms such as:

  • fatigue
  • muscle aches and pains
  • swelling
  • mild fever
  • numbness and tingling in the hands and feet
  • skin rashes, in the case of psoriasis

People with basophilia as a result of a myeloproliferative disorder may have varying symptoms depending on which disorder they have. Symptoms may include:

  • weakness
  • headaches
  • vision changes
  • easy bleeding and bruising
  • shortness of breath
  • numbness or tingling in the hands and feet
  • bone pain

Symptoms of the underlying causes of basophilia are different for everyone. People with unexplained symptoms that do not resolve over time should visit their doctor.

Doctors often notice basophilia during a complete blood count with differential (CBC with diff). When the differential reveals high levels of basophils, a doctor will likely order more tests to determine the cause.

Based on a person’s other symptoms, these tests can include a combination of the following:

  • blood tests
  • bone marrow biopsy
  • ultrasounds and imaging tests
  • genetic testing

Basophilia alone does not cause complications, but the underlying causes of basophilia may. Complications vary based on the cause of basophilia and may be severe.

These include the following:

  • heavy bleeding
  • enlarged spleen
  • frequent infections
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Taking antihistamines can help prevent allergy symptoms.

Basophilia is not likely to be treated directly. Instead, treatment will focus on the person’s underlying medical condition.

Bacterial infections that cause basophilia will require antibiotics. A doctor may also recommend rest and plenty of fluids.

Treatments for allergies include:

  • avoiding the allergen
  • antihistamines
  • hydrocortisone cream
  • corticosteroids
  • epinephrine

Treatment for inflammatory diseases, such as rheumatoid arthritis and IBD, may include immunosuppressants and anti-inflammatory medications.

Treatment for a myeloproliferative disorder is likely to be complex and will vary depending on an individual’s situation. It may include the following:

The outlook for people with basophilia varies based on the underlying cause. Mild infections should clear up with rest and treatment.

Inflammatory diseases and allergies are often life-long conditions that can be managed with medications and lifestyle changes.

People with basophilia caused by a severe condition, such as a myeloproliferative disorder, should develop an individualized treatment plan with their doctor.