Neutropenia is the most common serious risk of cancer treatment. It occurs when white blood cells called neutrophils drop below a healthy range, putting you at increased risk of infections.

Chemotherapy is a critical part of treatment for many types of cancer. More than 1 million people with cancer in the United States receive chemotherapy or radiation therapy each year.

Chemicals in chemotherapy drugs help kill cancer cells, but they can also damage healthy cells in your body. Cells that replicate quickly are especially at risk of being damaged, which can lead to side effects such as neutropenia.

Neutropenia is when you have a low number of neutrophils in your blood. Neutrophils are the most common white blood cells in your body. Having a lower-than-normal neutrophil count puts you at risk of developing infections and may limit the amount of chemotherapy that doctors can safely administer to you.

Keep reading to learn more about chemotherapy-induced neutropenia, including how it’s managed, when it’s most likely to occur, and how it’s recognized.

Chemotherapy-induced neutropenia is when the number of neutrophils in your blood drops below a healthy level. It’s a very common side effect of cancer treatment. In a 2019 study, researchers found that neutropenia made up 44% of unplanned chemotherapy delays in a group of 214 people with colorectal cancer.

Neutropenia is usually defined as a neutrophil count under 2,000 cells per cubic millimeter of blood (cells/mm3). The National Cancer Institute grades neutropenia from 0 to 4 depending on its severity.

GradeNeutrophil count (cells/mm3)
0 (healthy range)Over 2,000

Chemotherapy drugs contain chemicals that can kill cancer cells and also damage healthy cells throughout your body. The special stem cells inside of your bone marrow that produce blood cells are particularly prone to damage from these chemicals.

Neutropenia is estimated to occur in about 13 to 21% of people undergoing chemotherapy. It’s most likely to occur during your first round of chemotherapy.

People who are immunocompromised before treatment, such as those living with HIV or those who received an organ transplant, are at an elevated risk of developing neutropenia. Being over the age of 65 is also a risk factor.

If you have neutropenia, your immune system is compromised and you’re more prone to infections. Even a relatively minor infection might become severe. Infections tend to be more common and serious as your neutrophil count decreases.

Symptoms of infection can include:

A doctor or healthcare professional may diagnose you with neutropenic fever if your temperature rises above 101°F (38.3°C) or above 100.4°F (38°C) for at least an hour and you have a low neutrophil count. It’s the most common serious risk of cancer treatment.

People with neutropenia are at an increased risk of developing serious infections that can be life threatening.

Neutropenia is caused by damage to your cells that produce blood cells. Factors that influence how likely you’re to develop neutropenia include:

  • the type of chemotherapy you receive
  • whether you have a blood cancer such leukemia
  • how far your cancer has spread
  • whether you’re also receiving radiation therapy
  • your age
  • whether you have other health problems

It’s estimated that people with diabetes or hyperglycemia have a 32% higher chance of developing neutropenia than people without these conditions.

Doctors can diagnose neutropenia with a type of blood test called a complete blood cell count.

You’ll also likely receive this test regularly during your treatment to monitor how well your body is handling chemotherapy.

Neutropenia is often the side effect that limits the amount of chemotherapy doctors can administer.

A doctor may recommend delaying your next round of chemotherapy or lowering your dose if you develop neutropenia. Adjusting treatment may make chemotherapy less effective, so a doctor can help you weigh the pros and cons.

A doctor may also recommend taking antibiotics to prevent infection if your neutrophil count stays suppressed (below healthy levels) for an extended time.

They may prescribe you medications called granulocyte colony-stimulating factors. These medications help your body produce more white blood cells. They’re not given to everybody with neutropenia because they can cause side effects such as bone pain and fever.

According to the Centers for Disease Control and Prevention (CDC), there’s little you can do to prevent neutropenia, but you can take steps to lower your risk of infection.

Some of the ways you can protect yourself include:

  • washing your hands carefully and frequently
  • staying away from people who are sick
  • avoiding crowded areas such as shopping malls
  • avoiding dental work unless a doctor says it’s OK
  • avoiding foods with a high risk of bacterial contamination such as raw or undercooked eggs, seafood, or meat
  • washing raw fruit and vegetables thoroughly
  • getting a flu shot as soon as it’s available
  • keeping your living space as clean as possible
  • using gloves when gardening
  • wearing gloves when contacting pet urine or feces
  • using a soft toothbrush for your teeth and a mouthwash if recommended by your cancer team

Does chemotherapy-induced neutropenia affect the outlook for people with cancer?

Chemotherapy-induced neutropenia is associated with an improved outlook for those with some types of cancers, possibly because it’s a marker of effective chemotherapy. For example, in a 2021 review, researchers found neutropenia was associated with longer overall survival in people with advanced non-small cell lung cancer.

When does neutropenia usually occur following chemotherapy?

Your neutrophil count generally starts to drop a week after receiving a round of chemotherapy and reaches its lowest point 7 to 12 days after treatment. Your neutrophil levels might not return to healthy levels for 3 to 4 weeks.

Do all people receiving chemo get neutropenia?

Not everybody who receives chemotherapy develops neutropenia. However, it’s one of the most common side effects.

Does chemotherapy-induced neutropenia occur more frequently with certain kinds of chemo medications?

The risk of neutropenia varies based on the type of chemotherapy you receive. Types of chemotherapy drugs associated with neutropenia include:

  • vinblastine
  • taxanes
  • mitomycin C
  • hydroxyurea
  • epipodophyllotoxins
  • camptothecins
  • antimetabolites
  • anthracyclines
  • alkylating agents

Is neutropenia life threatening?

Neutropenia weakens your immune system and makes you more prone to infections. Even infections that are usually mild can become life threatening if your body can’t adequately defend them.

Chemotherapy-induced neutropenia is a common risk of chemotherapy. It develops when the number of neutrophils in your blood drops under a healthy range.

People with neutropenia are at an increased risk of developing infections.

If a doctor diagnoses you with neutropenia, they may recommend delaying or reducing your next round of chemotherapy. They may also give you drugs to help stimulate the production of new white blood cells. These drugs aren’t given to everybody because they can cause side effects.