An Overview on How to Increase White Blood Cells During Chemotherapy

Chemotherapy can leave you at risk for infection

Chemotherapy treats cancer, but it can also bring about side effects like a low white blood cell count. Having a low white blood cell count, also known as leukopenia, can leave you more susceptible to infections during treatment.

Luckily, there are a few things you can do to increase your white blood cells while you’re undergoing chemotherapy treatment for cancer. Taking these steps can strengthen your immune system and better fight off germs that make you sick.

This article will describe why chemotherapy influences white blood cell counts, how to tell if your counts are low, and ways to increase your white blood cells during chemo and lower your risk for infection.

WBS During Chemotherapy - Illustration by Michela Buttignol

Verywell / Michela Buttignol

How Does Chemotherapy Work?

Chemotherapy treatments are drugs that kill or damage fast-growing cells. Cancer cells grow and divide quickly, so these drugs can kill cancer, potentially slowing the growth of a tumor or even shrinking it.

But chemotherapy is nonspecific and is often administered to the entire body. This means that noncancerous fast-growing body cells may also be damaged and killed. The damage that chemotherapy does to normal cells is what causes chemotherapy’s typical side effects:

Chemo and White Blood Cell Counts

Your body is continually creating and replenishing your body's supply of white blood cells from a spongy tissue in your bones called bone marrow. These cells in the bone marrow are continually dividing, giving rise to new generations of white blood cells, red blood cells, and platelets. 

Because they're constantly generating new cells, bone marrow is a fast-growing tissue. Unfortunately, chemotherapy lowers white blood cell count by hurting the cells in the bone marrow, decreasing how many white blood cells the body puts out. 

How much impact chemotherapy has on your white blood cell counts depends on what medications you're on, how high your dose is, how often you're getting chemotherapy, your age and general health, and the type and stage of your cancer.

These changes to the white blood cells can begin as early as a few days to a week after starting your chemotherapy treatment. After that, they'll keep dropping until a week or two after your chemotherapy treatment cycle finishes, then they'll begin recovering.

Lowered white blood cell counts are called neutropenia or leukopenia. Generally, this is called immunosuppression—the chemotherapy has suppressed your immune system.

Your white blood cells are an essential line of defense against germs like bacteria and viruses that might make you sick. When the white blood cell count is low, your body has more difficulty fighting off infections. As a result, you may get sick more often or get sicker than you usually would. 

Before you start a new cycle of chemotherapy, your doctor should order a test to determine if your white blood cells have returned to a normal or healthy level.

Signs Your White Blood Cell Count Is Low

Your doctor will check your blood cell counts often during cancer diagnosis and treatment. The test may be called a complete blood cell count (CBC) or "hemogram." These tests take your blood and count the number of cells of different types.

White blood cells of all types are called leukocytes. The total leukocyte count will tell you about your white blood cell levels. Neutrophils are a specific type of white blood cell that are first responders to infections, and they may be reported separately:

You may have low white blood cell counts if you're getting sick more often than usual or getting sicker than usual. You may also develop a fever, cough, intestinal distress, or other symptoms of an infection.

There are few symptoms directly associated with lowered white blood cell counts, but you may start to feel more tired and run-down when your levels get low. In addition, people are more at risk of developing lowered white blood cell (WBC) levels during chemotherapy if they are over 70 or already have a lowered immune system.

Ways to Increase WBCs During Chemotherapy

Ensuring you’re eating a healthy diet with enough protein, vitamin B12, and folate is essential, so talk to your doctor or another medical professional on your care team about referring you to a dietitian. 

The dietitian can discuss your diet and how to improve it to boost your immunity by eating enough calories, protein, and vitamin-rich foods. Still, there’s no one thing you can eat or avoid eating to improve your white blood cell counts.

You should not start a supplement or vitamin without checking with your doctor or dietitian. Some vitamins and minerals can interfere with your treatment and make chemotherapy less effective.

Treating a Low White Blood Cell Count

If your doctor finds that your white blood cell counts are low, they may hold off on your next round of chemotherapy to let your body recover. 

They may also prescribe drugs called colony-stimulating factors, white blood cell growth factors, or myeloid growth factors. These drugs can help increase your white blood cell numbers but come with some risks. 

Not every patient is a good candidate to get these drugs. Your doctors will balance the benefits and risks of using these drugs based on guidelines from the American Society of Clinical Oncology and others.

If you’re showing signs of infection and have a lowered white blood cell count, your doctor might prescribe antibiotics as a precaution.


Chemotherapy attacks fast-growing cancer cells, but it can also affect other fast-growing cells of the body, such as those that produce white blood cells in the bone marrow. This can lead to low white blood cell counts and increase the risk for infection.

Your medical team will check your WBC count during chemotherapy. If it is low, they may delay further treatment or prescribe medication to stimulate your bone marrow. They may also prescribe antibiotics to prevent or treat infections.

A Word From Verywell

Chemotherapy can be very hard on the body. But you don't need to simply tolerate difficult side effects. Side effects do not mean that the chemotherapy is working any better to kill cancer. Speak with your palliative care team about holistic options for relieving the side effects of your chemotherapy. 

If you have a low white blood cell count, take precautions to avoid getting infections. These can include wearing a mask, keeping your distance from sick people, and regularly washing or sanitizing your hands.

Frequently Asked Questions

  • How long does it take to increase white blood cells during chemotherapy?

    Your white blood cell count will likely continue to decrease during the active phase of your chemotherapy treatment. When treatment ends for any given cycle, it can take one to two weeks for white blood cell counts to drop to their lowest point. From there, white blood cell counts should start rising back to normal levels, a process that may take three to four weeks.

  • Is there a way to increase white blood cells naturally?

    While eating a healthy diet with enough calories, protein, and vitamins is important for sustaining a healthy immune system, there’s no diet or natural remedy that can boost your white blood cell counts directly.

  • When should I be worried about having low white blood cells during chemo?

    White blood cell counts drop to their lowest about a week or two after finishing chemotherapy. At this point, you should be most worried about having a low blood cell count or getting an infection.

    If you feel like you’re catching infections a lot, or you are getting sicker than usual, check with your doctor. See if they have any suggestions for improving your counts and generally supporting your immune system through these treatments.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Cancer Society. How chemotherapy drugs work.

  2. American Cancer Society. Why people with cancer are more likely to get infections.

  3. American Society of Clinical Oncology. Neutropenia.

  4. American Cancer Society. Low white blood cell counts (neutropenia).

  5. American Cancer Society. Benefits of good nutrition during cancer treatment.

  6. Smith TJ, Bohlke K, Lyman GH, et al. Recommendations for the use of WBC growth factors: American Society of Clinical Oncology clinical practice guideline update. J Clin Oncol. 2015;33(28):3199-3212. doi:10.1200/JCO.2015.62.3488

By Jennifer Welsh
Jennifer Welsh is a Connecticut-based science writer and editor with over ten years of experience under her belt. She’s previously worked and written for WIRED Science, The Scientist, Discover Magazine, LiveScience, and Business Insider.