Nadir: A Common Side Effect of Chemotherapy

"Nadir" is a term that refers to the lowest point of anything. In medical terms, "nadir" could mean the lowest concentration of a drug in the body. Regarding chemotherapy, it typically describes the point at which blood cell counts are at their lowest after a chemotherapy treatment. It is commonly referred to as the "nadir period" or simply "nadir" among healthcare workers and patients.

This article will explain more about nadir and what it entails, as well as how to manage it and what you should watch out for.

Illustration of red and white blood cells
Ryan Etter / Ikon Images / Getty Images

Why Nadir Occurs

While chemotherapy directly targets cancer cells, it also affects other normal rapidly dividing cells in the process. This includes cells found in the gut, lining of the mouth, hair, and bone marrow, where the blood cells are produced.

During chemotherapy, bone marrow activity may be decreased, resulting in lowered blood cell counts within the body, including red blood cells, white blood cells, and platelets.

With each chemotherapy treatment comes a nadir period, so people who have frequent treatments may experience lowered counts more often than those whose treatments are spaced further apart.

Timeline and Risks

Each blood cell type reaches nadir at different times. Low counts have varying effects as well.

White Blood Cells

White blood cells (WBCs) generally drop to their lowest count about seven to 14 days after chemotherapy.

WBCs, especially a specific type called neutrophils, are a vital component of the immune system as they keep invading bacteria at bay. Because of this, you are at a heightened risk of developing infections when counts are low.

What Is a Normal Neutrophil Count?

A normal neutrophil count is 2,500– 6,000. A number lower than that range indicates that the immune system is compromised, and your risk of infection increases. If neutrophils are abnormally low—below 500—the condition is called neutropenia, and serious infection can occur.

Red Blood Cells

Red blood cells (RBCs) generally live longer than WBCs and reach a nadir period several weeks after treatment. Their job is to carry oxygen from the lungs to tissues throughout the body.

RBCs contain hemoglobin, an iron-rich protein that transports oxygen and also gives blood its red color. When RBC counts are too low, the result is called anemia.


Platelets generally reach their nadir period at about the same time as WBCs. Platelets serve an important function by helping blood clot, which prevents bleeding.

When the number of platelets in the body falls too low, the condition is called thrombocytopenia. It is marked by bruising, nosebleeds, excessive bleeding from cuts, and fatigue. A reddish-purple skin rash that looks like small dots is also a symptom of a low platelet count.

Managing Lowered Blood Cell Counts

When blood counts become too low, WBCs, RBCs, and platelets can be increased through drugs that boost cell production, as well as through transfusions.

The following vitamins and minerals help increase the body's production of RBCs. Consider adding supplements and/or eating foods that are rich in the following:

  • Iron: Found in leafy green vegetables like kale and spinach, organ meats, lean red meat, egg yolks, beans, and legumes
  • Vitamin A (retinol): Found in cod liver oil, sweet potatoes, spinach, broccoli, black-eyed peas, carrots, squash, pumpkin, cantaloupe, mango, and apricots
  • Vitamin B6 (pyridoxine): Found in salmon, poultry, eggs, potatoes, sweet potatoes, bananas, avocado, pistachios, peanuts, whole grains, and brown rice
  • Vitamin B9 (folate): Found in citrus, banana, papaya, beets, asparagus, brussels sprouts, avocado, walnuts, and flax seeds
  • Vitamin B12 (cobalamin): Found in organ meat, beef, tuna, trout, salmon, sardines, clams, and eggs
  • Vitamin C: Found in citrus, cantaloupe, kiwi, papaya, strawberries, sweet potatoes, tomatoes, bell peppers, broccoli, cauliflower, and kale
  • Copper: Found in shiitake mushrooms, spirulina, almonds, cashews, sesame seeds, lobster, oysters, organ meats, Swiss chard, spinach, and kale
  • Vitamin E: Found in salmon, trout, shrimp, goose, spinach, broccoli, turnip greens, squash, avocados, wheat germ oil, olive oil, sunflower seeds, almonds, hazelnuts, pine nuts, peanuts, Brazil nuts, mango, and kiwi

Increasing your consumption of certain healthy meats, fruits, and vegetables can also help boost the body's natural production of blood cells.

Protein sources like poultry and fish may promote the production of WBCs. Platelets can be increased by eating foods rich in vitamins B9 and B12.

Precautions to Take During Nadir

It's important to avoid infection or any activities that could induce bleeding, as WBCs that fight infection and platelets that help with clotting are diminished. Follow some simple tips, including:

  • Washing hands often
  • Thoroughly washing and cooking food before consuming
  • Avoiding contact with those who may carry infection, as well as pet waste
  • Avoiding getting scratches or cuts

Help boost your immune system by:

  • Getting enough sleep
  • Eating a healthy, balanced diet rich in fruits and vegetables
  • Avoiding caffeine and alcohol
  • Drinking plenty of water

When to See a Healthcare Provider

Seek immediate medical attention if you have bleeding that won't stop or a fever of 100 degrees or higher, as that could indicate the presence of a serious infection.


"Nadir" is a term describing when white blood cells are at their lowest, putting an individual at risk for infection and other complications. It's important to take extra precautions to reduce the risk of infections and boost the immune system.

Since bone marrow production may also reach a low point during nadir, it's also important to boost red blood cell and platelet production. Eating a diet rich in vitamins and minerals can help your body build up blood cell counts and keep you as healthy as possible.

A Word From Verywell

During chemotherapy, it's important to try to stay as healthy as possible. Talk with your treatment team about ways you can keep yourself safe when your blood cell counts fall into unhealthy ranges. Medical interventions, as well as making dietary changes and taking extra precautions, may be of help.

Frequently Asked Questions

  • How long does the nadir phase last?

    The nadir phase starts about 10 days after treatment, but this can vary, depending on the drug or drugs you are on. Blood counts will generally get back to normal within three to four weeks.

  • How do you feel during nadir?

    It all depends on the person. You may feel especially tired or worn out, and some people may feel "down" or depressed.

7 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. The American Cancer Society. Chemotherapy for liver cancer.

  2. Canadian Cancer Society. Low blood cell counts.

  3. The American Cancer Society. Understanding your lab test results.

  4. The American Cancer Society. Low red blood cell counts (Anemia).

  5. The American Cancer Society. Low blood counts, fever, and infections.

  6. Harvard Health Publishing. How to boost your immune system.

  7. ChemoCare. Nadir.

Additional Reading
Originally written by Lisa Fayed