Anemia and Cancer Treatment
A plain-language explanation of anemia during cancer treatment—what it is, its signs, why it happens, and ways to manage it—based on National Cancer Institute resources.
Source: National Cancer Institute · NCI reviewed 2021-09-23 · Verified 2026-07-02
The 30-second version
Anemia means the number of red blood cells is below normal. Red blood cells carry oxygen through your body, so anemia can make you feel very tired, short of breath, or lightheaded. Cancer treatments like chemotherapy and radiation therapy, and cancers that affect the bone marrow, can cause it. Blood tests check for anemia, and there are treatments that may help.
Key takeaways
- Anemia is a condition in which the number of red blood cells is below normal.
- Red blood cells carry oxygen from the lungs throughout your body, so anemia can make you feel very tired.
- Signs may include shortness of breath, feeling dizzy or faint, headaches, a fast heartbeat, and pale skin.
- Chemotherapy, radiation therapy, and cancers that affect the bone marrow can cause anemia.
- Blood tests check for anemia, and treatment is based on your symptoms and what is causing it.
- Saving your energy, balancing rest with activity, and eating and drinking well may help.
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The full explanation.
What anemia is
Anemia is a condition in which the number of red blood cells is below normal. Red blood cells are the cells that carry oxygen from the lungs throughout your body to help it work properly. When you are anemic, your body does not have enough red blood cells to move oxygen the way it should.
Because oxygen reaches your body through red blood cells, having too few can leave you feeling drained.
Signs of anemia
Anemia can make you feel very tired, short of breath, and lightheaded. Signs of anemia may also include:
- feeling dizzy or faint
- headaches
- a fast heartbeat
- pale skin
Tell your doctor if you are extremely tired or notice other signs of anemia. There are treatments that may help.
Why it happens during cancer treatment
Cancer treatments such as chemotherapy and radiation therapy can cause anemia. Cancers that affect the bone marrow—the soft tissue inside bones where blood cells are made—can also cause it.
You will have blood tests to check for anemia. Treatment for anemia is based on your symptoms and on what is causing the anemia. Because there can be different causes, your healthcare team looks at the whole picture before deciding what may help.
Ways to manage anemia
If you have fatigue caused by anemia, these steps may help:
- Save your energy and ask for help. Choose the most important things to do each day. When people offer to help, let them—they can take you to the doctor, make meals, or do other things you are too tired to do.
- Balance rest with activity. Take short naps during the day, but keep in mind that too much bed rest can make you feel weak. You may feel better if you take short walks or exercise a little every day.
- Eat and drink well. Talk with your doctor, nurse, or a registered dietitian to learn what foods and drinks are best for you. You may need to eat foods that are high in protein or iron.
Your healthcare team can tell you whether medicine, iron pills, a blood transfusion, or other treatments might help in your situation.
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Anemia and Cancer Treatment: the quick overview
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Suggested animation storyboard▾
- 1Open on a calm title card: "Anemia and Cancer Treatment" with the Cancer Explained mark.
- 2Narrator reads the 30-second summary while a soft animated diagram builds on screen: "Anemia means the number of red blood cells is below normal. Red blood cells carry oxygen through your body, so anemia can make you feel very tired, short of breath, or lightheaded. Cancer treatments like chemotherapy and radiation therapy, and cancers that affect the bone marrow, can cause it. Blood tests check for anemia, and there are treatments that may help."
- 3Scene 2: illustrate the idea — "Anemia is a condition in which the number of red blood cells is below normal."
- 4Scene 3: illustrate the idea — "Red blood cells carry oxygen from the lungs throughout your body, so anemia can make you feel very tired."
- 5Scene 4: illustrate the idea — "Signs may include shortness of breath, feeling dizzy or faint, headaches, a fast heartbeat, and pale skin."
- 6Close on a reminder card: this is educational only; talk with your healthcare team, and a link to the NCI source.
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Quick knowledge check
According to this article, what is anemia?
Frequently asked questions
▸What is anemia?
Anemia is a condition in which the number of red blood cells is below normal. Red blood cells carry oxygen from your lungs throughout your body to help it work properly.
▸What are the signs of anemia?
Anemia can make you feel very tired, short of breath, and lightheaded. Signs may also include feeling dizzy or faint, headaches, a fast heartbeat, and pale skin. Tell your doctor if you notice these signs.
▸Why does cancer treatment cause anemia?
Cancer treatments such as chemotherapy and radiation therapy, as well as cancers that affect the bone marrow, can cause anemia. When you are anemic, your body does not have enough red blood cells.
▸How is anemia found and treated?
You will have blood tests to check for anemia. Treatment is based on your symptoms and on what is causing the anemia. Your healthcare team can explain the options that fit your situation.
▸What can I do to feel better if I have anemia?
NCI suggests saving your energy and asking for help, balancing rest with activity, and eating and drinking well. Talking with your doctor, nurse, or a registered dietitian can help you learn what is best for you.
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Questions to ask your healthcare team
Consider bringing these questions to your next appointment.
- What is causing my anemia?
- What problems should I call you about?
- What steps can I take to feel better?
- Would medicine, iron pills, a blood transfusion, or other treatments help me?
- Could you give me the name of a registered dietitian who could give me advice?
- How will anemia affect my energy and daily activities?
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