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by Dr. C.H. Weaver M.D. 10/2022

Each year in the United States, an estimated five million people receive a blood transfusion.1 Transfusion may be necessary for patients who experience blood loss as a result of surgery or injury, or who have low blood counts as a result of certain medical conditions or treatments.

Blood consists of four main components: red blood cells, white blood cells, platelets, and plasma. These components may be transfused individually or together as whole blood.

Before transfusing blood or a blood component, it is important to ensure that the blood type is compatible with the blood type of the recipient. Blood type is categorized as A, B, AB, or O, and as Rh-positive or Rh-negative. Giving a patient the wrong blood type can lead to potentially fatal complications.

The focus of this review is red blood cell transfusion. Red blood cells carry oxygen to all parts of the body. An inadequate supply of red blood cells (anemia), decreases the oxygen-carrying capacity of blood, and can result in symptoms such as fatigue, shortness of breath, and dizziness. Anemia may develop in cancer patients either as a direct result of the cancer or as a side effect of cancer treatment. The condition is often diagnosed through a test known as a complete blood count (CBC).

In some cases, anemia requires treatment with a red blood cell transfusion. Although blood transfusions are usually safe and can be life-saving, there are potential risks. Understanding these risks is an important part of making informed decisions about blood transfusion.

Potential Risks

Donated blood is screened for infectious agents, and the U.S. blood supply is safer than ever before. It is not possible, however, to completely eliminate all risks. Blood transfusions carry a small risk of transmitting infectious diseases. The risk of infection with hepatitis B from donor blood, for example, is roughly 1 in 205,000. The risk of HIV is even lower, at roughly 1 in 2 million.2

Blood transfusions can sometimes cause allergic reactions. These reactions may be mild or severe, and can occur even when the correct blood type is given.

If the blood transfusion that you receive doesn’t work with your blood type, you may develop a rare but serious condition known as an acute immune hemolytic reaction. In patients with this condition, the body attacks the transfused red blood cells. The red blood cells then release substances which damage the kidneys.

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Other potential risks of blood transfusion include fever, lung injury, and graft-versus-host disease.2

In light of these and other potential transfusion risks, the American Red Cross Practice Guidelines for Blood Transfusion note that red blood cells should not be used to treat anemia that can be corrected with a non-transfusion therapy such as iron therapy.3

Other Ways to Treat Anemia

Blood transfusions are often used when a patient has severe anemia and/or requires a rapid increase in red blood cell levels. Some patients, however, may be able to manage their anemia through other approaches.

Erythropoietin: Erythropoietin is a blood cell growth factor that selectively increases production of red blood cells. Erythropoietin is FDA-approved for the treatment of anemia in selected patients with nonmyeloid cancers whose anemia is a result of chemotherapy. Treatment with erythropoietin causes a gradual increase in red blood cell production. The two commercially available forms of erythropoietin are darbepoetin alfa (Aranesp®) and epoetin alfa (Procrit®, Epogen®). Although erythropoietin has been shown to reduce the need for blood transfusions in patients with chemotherapy-induced anemia, some studies have reported serious adverse effects of erythropoietin in certain groups of patients. Patients who are considering erythropoietin therapy may wish to discuss the range of potential risks and benefits with their physician.

Dietary changes: Low levels of iron and certain vitamins can contribute to anemia. Your doctor may therefore recommend dietary changes or use of certain dietary supplements to help manage your anemia.4 Because not all dietary supplements are safe, be sure to talk with your doctor about what’s right for you.

Make an Informed Decision

If you need a blood transfusion, be aware that most transfusions go smoothly and that the procedure is life-saving for some patients. Like most medical procedures, however, there are some risks. By taking the time to learn about the potential risks and benefits, you’ll be able to make a fully informed decision about the procedure.


  1. National Heart Lung and Blood Institute. What is a blood transfusion? Available at:
  2. National Heart Lung and Blood Institute. What are the risks of a blood transfusion? Available at: Accessed February 11, 2010.
  3. American Red Cross. Practice Guidelines for Blood Transfusion, Second Edition. Available at: f
  4. National Heart Lung and Blood Institute. How is anemia treated? Available at: