Cancer Treatment Side Effect: Anemia

What it is and why it occurs

Red blood cells carry oxygen throughout your body. Anemia is when you have too few red blood cells to carry the oxygen your body needs. Your heart works harder when your body does not get enough oxygen. This can make it feel like your heart is pounding or beating very fast. Anemia can also make you feel short of breath, weak, dizzy, faint, or very tired.

Some types of chemotherapy cause anemia because they make it harder for bone marrow to produce new red blood cells.

Ways to manage

  • Get plenty of rest. Try to sleep at least 8 hours each night. You might also want to take 1 to 2 short naps (1 hour or less) during the day.

  • Limit your activities. This means doing only the activities that are most important to you. For example, you might go to work but not clean the house. Or you might order take-out food instead of cooking dinner.

  • Accept help. When your family or friends offer to help, let them. They can help care for your children, pick up groceries, run errands, drive you to doctor's visits, or do other chores you feel too tired to do.

  • Eat a well-balanced diet. Choose a diet that contains all the calories and protein your body needs. Calories will help keep your weight up, and extra protein can help repair tissues that have been harmed by cancer treatment. Talk to your doctor, nurse, or dietitian about the diet that is right for you.

  • Stand up slowly. You may feel dizzy if you stand up too fast.

When you get up from lying down, sit for a minute before you stand.

Your doctor or nurse will check your blood cell count throughout your chemotherapy. You may need a blood transfusion if your red blood cell count falls too low. Your doctor may also prescribe a medicine to boost (speed up) the growth of red blood cells or suggest that you take iron or other vitamins.

Call your doctor or nurse if:

  • Your level of fatigue changes or you are not able to do your usual activities

  • You feel dizzy or like you are going to faint

  • You feel short of breath

  • It feels like your heart is pounding or beating very fast


National Cancer Institute, U.S. National Institutes of Health (

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Last Editorial Review: 12/16/2009