Infection and Neutropenia During Cancer Treatment
A plain-language explanation of infection and neutropenia during cancer treatment—why the risk goes up, the signs to watch for, and ways to prevent infection—based on National Cancer Institute resources.
Source: National Cancer Institute · NCI reviewed 2020-01-23 · Verified 2026-07-02
The 30-second version
An infection is the invasion and growth of germs in the body. Some cancers and treatments like chemotherapy lower your white blood cells, which fight infection, raising your risk. When the neutrophil count is very low, this is called neutropenia. Infections during cancer treatment can be life threatening, so call your healthcare team right away if you notice signs of infection.
Key takeaways
- An infection is the invasion and growth of germs—like bacteria, viruses, yeast, or other fungi—in the body.
- Some cancers and treatments such as chemotherapy lower white blood cells, which help fight infection, raising your risk.
- Neutropenia is a condition in which there is a low number of neutrophils, a type of white blood cell.
- Signs of infection include a fever of 100.5 degrees F (38 degrees C) or higher, chills, cough or sore throat, and more.
- Infections during cancer treatment can be life threatening and need urgent medical attention.
- Washing your hands often, staying extra clean, and avoiding germs can help prevent infection.
Choose how you want to understand this
The full explanation.
What infection and neutropenia are
An infection is the invasion and growth of germs in the body, such as bacteria, viruses, yeast, or other fungi. An infection can begin anywhere in the body, may spread throughout the body, and can cause a range of signs.
Some types of cancer and treatments such as chemotherapy may increase your risk of infection. This is because they lower the number of white blood cells, the cells that help your body fight infection. During chemotherapy, there are times in your treatment cycle when the number of a type of white blood cell called neutrophils is particularly low and you are at increased risk of infection. Stress, poor nutrition, and not enough sleep can also weaken the immune system.
You will have blood tests to check for neutropenia—a condition in which there is a low number of neutrophils. Medicine may sometimes be given to help prevent infection or to increase the number of white blood cells.
When your infection-fighting cells are low, everyday germs can be more dangerous—so prevention matters.
Signs of infection
Call your healthcare team if you have signs of an infection, which can include:
- fever of 100.5 degrees F (38 degrees C) or higher
- chills
- cough or sore throat
- diarrhea
- ear pain, headache or sinus pain, or a stiff or sore neck
- skin rash
- sores or white coating in your mouth or on your tongue
- swelling or redness, especially where a catheter enters your body
- urine that is bloody or cloudy, or pain when you urinate
Infections during cancer treatment can be life threatening and require urgent medical attention. Be sure to talk with your doctor or nurse before taking any medicine—even aspirin, acetaminophen (such as Tylenol), or ibuprofen (such as Advil)—for a fever. These medicines can lower a fever but may also mask or hide signs of a more serious problem.
Ways to prevent infection
Your healthcare team will talk with you about these and other ways to prevent infection:
- Wash your hands often and well. Use soap and warm water to wash your hands well, especially before eating. Have people around you wash their hands well too.
- Stay extra clean. If you have a catheter, keep the area around it clean and dry. Clean your teeth well and check your mouth for sores each day. Clean any scrape or cut well. Let your doctor or nurse know if your bottom is sore or bleeds, as this could raise your risk of infection.
- Avoid germs. Stay away from people who are sick or have a cold. Avoid crowds and people who have just had a live vaccine, such as one for chicken pox, polio, or measles. Follow food safety guidelines—make sure meat, fish, and eggs are well cooked, keep hot foods hot and cold foods cold, and wash or peel raw fruits and vegetables as advised.
Food safety
Some cancer treatments make it easier to get sick from contaminated food. Handling and preparing food safely can help reduce your risk of foodborne illness. Your healthcare team can point you to food safety tips that fit your situation.
Watch instead
Animated lessons are in production. Here’s the planned video slate for this topic — each one will be based on the same NCI-sourced explanation you’re reading.
Infection and Neutropenia During Cancer Treatment: the quick overview
A one-breath explanation you can watch before an appointment.
Coming soonInfection and Neutropenia During Cancer Treatment, explained simply
The core ideas with friendly animation and plain language.
Coming soonUnderstanding infection and neutropenia during cancer treatment — full lesson
A deeper walkthrough covering the key takeaways and common questions.
Coming soonVideo transcript▾
A full, readable transcript will appear here when the video is published — so the lesson is accessible whether you prefer to watch, listen, or read. For now, the article above is the complete text version.
Suggested animation storyboard▾
- 1Open on a calm title card: "Infection and Neutropenia During Cancer Treatment" with the Cancer Explained mark.
- 2Narrator reads the 30-second summary while a soft animated diagram builds on screen: "An infection is the invasion and growth of germs in the body. Some cancers and treatments like chemotherapy lower your white blood cells, which fight infection, raising your risk. When the neutrophil count is very low, this is called neutropenia. Infections during cancer treatment can be life threatening, so call your healthcare team right away if you notice signs of infection."
- 3Scene 2: illustrate the idea — "An infection is the invasion and growth of germs—like bacteria, viruses, yeast, or other fungi—in the body."
- 4Scene 3: illustrate the idea — "Some cancers and treatments such as chemotherapy lower white blood cells, which help fight infection, raising your risk."
- 5Scene 4: illustrate the idea — "Neutropenia is a condition in which there is a low number of neutrophils, a type of white blood cell."
- 6Close on a reminder card: this is educational only; talk with your healthcare team, and a link to the NCI source.
Words to know
Tap any term to see what it means.
Quick knowledge check
According to this article, what is neutropenia?
Frequently asked questions
▸What is neutropenia?
Neutropenia is a condition in which there is a low number of neutrophils, a type of white blood cell that helps your body fight infection. During chemotherapy there are times in your treatment cycle when neutrophils are especially low and your risk of infection is higher. Blood tests check for neutropenia.
▸Why does cancer treatment raise the risk of infection?
Some cancers and treatments such as chemotherapy lower the number of white blood cells, the cells that help your body fight infection. Stress, poor nutrition, and not enough sleep can also weaken the immune system, making infection more likely.
▸What are the signs of infection I should watch for?
Signs can include a fever of 100.5 degrees F (38 degrees C) or higher, chills, a cough or sore throat, diarrhea, ear or sinus pain, a stiff or sore neck, skin rash, mouth sores, swelling or redness (especially where a catheter enters the body), and bloody or cloudy urine or pain when you urinate.
▸Should I take medicine for a fever on my own?
Talk with your doctor or nurse before taking any medicine—even aspirin, acetaminophen, or ibuprofen—for a fever. These medicines can lower a fever but may also mask or hide signs of a more serious problem.
▸How can I lower my risk of infection?
Wash your hands often and well, stay extra clean (including caring for any catheter site and your mouth), and avoid germs by staying away from people who are sick, avoiding crowds, and following food safety guidelines. Your healthcare team can share steps that fit your situation.
Test your understanding
A few quick questions to check what you took away. Not a test of anything medical — just a way to review.
0 of 4 answered
This quiz checks understanding of educational content only. It is not medical advice. Open this quiz on its own page.
Review key terms
Study 10 flashcards built from this topic’s key terms and common questions — flip each card to reveal a plain-language explanation.
Questions to ask your healthcare team
Consider bringing these questions to your next appointment.
- Am I at increased risk of infection during treatment? When am I at increased risk?
- What steps should I take to prevent infection?
- What signs of infection should I look for?
- Which signs mean I need urgent care at the emergency room, and which should I call you about?
- Should medicine be given to help prevent infection or increase my white blood cells?
Related learning map
How this explanation connects to 16 other things you can explore — related topics, terms, questions, practice, and its NCI source.
Topic area
Related explanations
Questions this answers