What depletes white blood cells? Causes and treatments

September 25, 2025 •

4 min read

According to the Mayo Clinic, a low white blood cell count can increase your risk of infection. This condition, known as leukopenia, is often a side effect of other medical issues or treatments. Understanding what depletes white blood cells is a critical step toward identifying the underlying problem and finding an appropriate solution.

Quick Summary

White blood cell levels can be lowered by various factors, including cancer treatments like chemotherapy and radiation, severe infections, autoimmune disorders, certain medications, and nutritional deficiencies, all of which compromise the body's immune defense.

Key Points

Chemotherapy & Radiation: These cancer treatments are a major cause of WBC depletion by harming bone marrow cells.
Infections: Severe viral diseases like HIV, hepatitis, and serious bacterial infections like sepsis can overwhelm or destroy WBCs.
Autoimmune Disorders: Conditions such as lupus and rheumatoid arthritis can cause the immune system to attack and destroy its own white blood cells.
Medications: Certain drugs, including specific antibiotics and immunosuppressants, have leukopenia as a potential side effect.
Nutritional Deficiencies: A lack of essential vitamins like B12 and folate, often linked to malnutrition, can hinder WBC production in the bone marrow.
Bone Marrow Problems: Conditions like aplastic anemia or leukemia directly impact the bone marrow's ability to create a healthy number of blood cells.

Understanding the role of white blood cells

White blood cells (WBCs), or leukocytes, are essential components of the immune system. They act as the body's primary line of defense against disease-causing invaders like bacteria, viruses, fungi, and parasites. When the level of these cells drops below the normal range, a person becomes more susceptible to infections. This drop can be caused by problems with the production of WBCs in the bone marrow, increased destruction of these cells, or the sequestration of WBCs within the spleen.

Medical treatments that lower white blood cells

Chemotherapy and radiation therapy

Chemotherapy drugs are designed to kill rapidly dividing cells, including cancer cells. Unfortunately, this process also damages other fast-growing cells in the body, such as the white blood cells produced in the bone marrow. This leads to a temporary, but significant, drop in the WBC count, a period known as the nadir. Similarly, radiation therapy that involves large areas of bone can have a similar suppressive effect on WBC production. Healthcare providers closely monitor blood counts during these treatments to manage the risk of infection.

Medications

Beyond cancer treatments, a variety of other medications can lead to a decrease in white blood cell levels. Some of the most common culprits include:

Antibiotics: Some, like sulfonamides, can cause a drop in WBCs.
Immunosuppressants: Drugs used to suppress the immune system, such as those for autoimmune diseases or organ transplant recipients, naturally lower WBC counts.
Antipsychotics: Certain antipsychotic medications have been linked to leukopenia.
Diuretics: Some diuretics, or 'water pills', can also have this effect.

Infections and their impact on WBCs

Viral infections

Many viruses can interfere with white blood cell production or cause their destruction. Infections such as HIV, hepatitis, measles, and the Epstein-Barr virus (which causes mononucleosis) are known causes of leukopenia. HIV, in particular, targets and destroys T-cells, a specific type of white blood cell, severely weakening the immune system.

Bacterial and other infections

Severe infections, particularly those that enter the bloodstream (sepsis), can cause the body to use up white blood cells faster than they can be produced. Tuberculosis and malaria are other infections known to cause WBC depletion as the body fights off the infection.

Autoimmune diseases and bone marrow problems

Autoimmune disorders

In autoimmune diseases, the immune system mistakenly attacks the body's own healthy tissues and cells. Conditions like lupus (systemic lupus erythematosus) and rheumatoid arthritis can instruct the body to destroy its own white blood cells, leading to chronic leukopenia.

Bone marrow disorders

Since the bone marrow is the factory for producing blood cells, any disorder affecting it can cause a low WBC count. Conditions include:

Aplastic anemia: A rare condition where the bone marrow stops producing enough new blood cells.
Myelodysplastic syndromes (MDS): A group of disorders caused by poorly formed or dysfunctional blood cells produced by the bone marrow.
Leukemia: Cancers of the bone marrow, such as leukemia, can crowd out and inhibit the production of healthy white blood cells.

Nutritional and lifestyle contributors

Vitamin deficiencies

Severe malnutrition and a lack of certain vitamins can directly affect the production of white blood cells. Deficiencies in vitamins like B12, folate, and copper are particularly damaging to this process, leading to low WBC counts.

Excessive alcohol consumption and smoking

Chronic alcohol abuse and cigarette smoking have been linked to lower white blood cell counts. Excessive alcohol can interfere with the absorption of necessary nutrients and suppress bone marrow function. Smoking can also negatively impact immune function and affect blood cell levels.

Chronic stress

While not as directly impactful as other factors, prolonged or severe physical and emotional stress can also affect the immune system and has been associated with lower white blood cell counts.

Comparing causes of leukopenia


Cause Category	Example Conditions/Factors	Effect on WBCs	Severity	Management Approach
Medical Treatments	Chemotherapy, Radiation	Destroys fast-growing cells in bone marrow	Often temporary but can be severe	Supportive care, treatment delays, growth factors
Infections	HIV, Hepatitis, Sepsis	Overwhelms, destroys, or suppresses production	Varies, can be acute or chronic	Treating the underlying infection
Autoimmune Disorders	Lupus, Rheumatoid Arthritis	Immune system attacks and destroys WBCs	Can be chronic and persistent	Immunosuppressants
Bone Marrow Issues	Aplastic Anemia, Leukemia	Inhibits or prevents blood cell production	Often serious and long-term	Transplant, specific cancer treatments
Nutritional Factors	B12, Folate deficiency	Impacts production process in bone marrow	Usually corrects with supplementation	Nutrient replacement

Management and increasing white blood cells

If a healthcare provider determines you have leukopenia, they will work to identify and treat the underlying cause. Strategies can vary widely depending on the trigger.

Treating the underlying cause

For infections, this may mean a course of antibiotics or antiviral medication. For autoimmune disorders, it involves managing the condition itself. In cases where a medication is responsible, your doctor may adjust the dosage or switch you to an alternative drug.

Medications to stimulate production

In severe cases, particularly for cancer patients, doctors may prescribe medications called granulocyte colony-stimulating factors (G-CSFs). These drugs, given as injections, stimulate the bone marrow to produce more white blood cells.

Dietary and lifestyle support

While no specific diet guarantees an increase in WBCs, a balanced and nutritious diet is crucial for overall immune health. This includes consuming enough protein and ensuring adequate intake of vitamins like B12 and folate. Managing stress, getting adequate sleep, and avoiding excessive alcohol and tobacco use also support a healthy immune system.

When to seek medical attention

Because a low white blood cell count can be a sign of a serious underlying condition, it is vital to consult a healthcare provider for a proper diagnosis and treatment plan. A blood test called a Complete Blood Count (CBC) is the standard method for checking WBC levels. You should seek immediate medical attention if you experience a fever or other signs of infection while having a low WBC count. The American Cancer Society provides a useful resource on understanding and managing low blood counts [https://www.cancer.org/cancer/managing-cancer/side-effects/low-blood-counts/neutropenia.html].

Frequently Asked Questions

A critically low white blood cell count, or leukopenia, means your body is at a much higher risk of developing an infection. It can indicate a serious underlying issue, such as a severe infection, bone marrow problem, or a reaction to certain medical treatments.

A doctor can diagnose leukopenia through a routine blood test called a Complete Blood Count (CBC). To determine the underlying cause, they may order further tests, including blood work, imaging, or a bone marrow biopsy, based on your medical history and other symptoms.

Yes, many viral infections, such as the flu, hepatitis, or Epstein-Barr virus, can temporarily cause a drop in white blood cells. The count often returns to normal as the body recovers from the infection.

While no specific foods are proven to raise WBCs, a nutritious diet rich in vitamins and minerals is vital for supporting bone marrow function. Eating lean proteins, leafy greens, and foods with B12 and folate can support your body's ability to produce healthy blood cells.

Managing stress, getting adequate sleep, staying hydrated, and limiting alcohol consumption and smoking can support a healthy immune system and overall blood cell production. Following these healthy habits can help the body function optimally.

A low white blood cell count often has no symptoms of its own. However, it can lead to frequent or severe infections. If you have leukopenia, you may experience fevers, chills, mouth sores, or other signs of infection, especially during treatments like chemotherapy.

If you have been diagnosed with leukopenia or are undergoing a treatment known to cause it, you should contact your doctor if you experience a fever of 100.4°F or higher, shaking, chills, or any signs of an infection.