Blood Transfusion

A blood transfusion is a common, safe medical procedure in which healthy blood is given to you through an intravenous (IV) line that has been inserted in one of your blood vessels.

Your blood carries oxygen and nutrients to all parts of your body. Blood transfusions replace blood that is lost through surgery or injury or provide it if your body is not making blood properly. You may need a blood transfusion if you have anemia, sickle cell disease, a bleeding disorder such as hemophilia, or cancer. For people in critical condition, blood transfusions can be lifesaving.

Four types of blood products may be given through blood transfusions: whole blood, red blood cells, platelets, and plasma. Most of the blood used for transfusions comes from whole blood donations given by volunteer blood donors. A person can also have his or her own blood collected and stored a few weeks before surgery in case it is needed.

After a doctor determines that you need a blood transfusion, he or she will test your blood to make sure that the blood you are given matches your blood type. A small needle is used to insert an IV line in one of your blood vessels. Through this line, you receive healthy blood. Blood transfusions usually take 1 to 4 hours to complete. You will be monitored during and after the procedure.

Blood transfusions are usually very safe, because donated blood is carefully tested, handled, and stored. However, there is a small chance that your body may have a mild to severe reaction to the donor blood. Other complications may include fever, heart or lung complications, alloimmunization, and rare but serious reactions in which donated white blood cells attack your body’s healthy tissues. Some people have health problems from getting too much iron from frequent transfusions. There is also a very small chance of getting an infectious disease such as hepatitis B or C or HIV through a blood transfusion. For HIV, that risk is less than one in 1 million. Scientific research and careful medical controls make the supply of donated blood very safe. Blood transfusions are among the most common medical procedures in the nation.

Research for Your Health

The NHLBI is part of the U.S. Department of Health and Human Services’ National Institutes of Health (NIH)—the Nation’s biomedical research agency that makes important scientific discovery to improve health and save lives. We are committed to advancing science and translating discoveries into clinical practice to promote the prevention and treatment of heart, lung, blood, and sleep disorders including the improvement of blood transfusion. Learn about current and future NHLBI efforts to improve health through research and scientific discovery.

Improving health with current research
- Blood Transfusion

Learn about the following ways the NHLBI continues to translate current research into improved health for people who give the gift of life, and for people across the lifespan who need a blood transfusion. Research on this topic is part of the NHLBI’s broader commitment to advancing blood disorders and blood safety scientific discovery.

  • The REDS-IV-Pediatric (REDS-IV-P) Program That Helps Protect Blood Donors And Blood Transfusion Recipients. The NHLBI started the Recipient Epidemiology and Donor Evaluation Study (REDS) program in 1989 to protect the Nation’s blood supply from threats, improve the benefits of transfusions, and reduce the risks of transfusions. Now in its fourth phase, called REDS-IV-Pediatric, this program supports research in the United States and around the world to evaluate and improve the health of blood donors and the safety and effectiveness of transfusion therapies in children and adults. REDS-IV-P also includes research to evaluate and prevent the transmission of infection through blood transfusions.
  • An NHLBI Workshop to Guide Research Goals for Red Blood Cell Products. We held a workshop in 2018 where researchers and experts made recommendations to guide future research on new technologies and biomarkers that could be developed and used to assess tissue oxygenation before and after transfusions of red blood cells.
  • NHLBI-funded Research That Supported Changes in Blood Transfusion Guidelines. Clinical trials funded by the NHLBI helped determine that the previous blood transfusion guidelines sometimes led to unnecessary transfusions. The current guidelines will limit unnecessary transfusions and help reduce the risks and complications linked to blood transfusions.
  • Identifying Transfusion Strategies for Severely Injured Patients. An NHLBI-funded study compared two transfusion methods designed to better deliver blood transfusions to critically injured patients. The study found that the two methods were equally effective at helping patients survive their injuries. These results will help increase the treatment options available to patients. View No difference in long-term mortality found when investigators tested two blood transfusion methods in severely injured trauma patients for more information.
  • Using Blood Transfusions to Treat Complications of Sickle Cell Disease. The NHLBI leads or sponsors many studies on the use of blood transfusions for the treatment of sickle cell disease. These studies have led to advances in the use of blood transfusions to manage anemia, prevent organ failure, and reduce the risk of stroke in patients who have sickle cell disease. View Evidence-Based Management of Sickle Cell Disease and Blood transfusions may mean fewer strokes in kids with sickle cell disease for more information.

Advancing research for improved health
- Blood Transfusion

In support of our mission, we are committed to advancing blood transfusion research in part through the following ways.

  • We perform research. Our Division of Intramural Research, which includes investigators from the Hematology and Sickle Cell branches, perform research on conditions that require a blood transfusion.
  • We fund research. The research we fund today will help improve our future health. Our Division of Blood Diseases and Resources, which includes the Blood Epidemiology and Clinical Therapeutics Branch and Translational Blood Science and Resources Branch, oversees much of the research on blood transfusion medicine we fund. This helps us to improve upon the safety of blood and blood products and their use in the treatment and management of conditions such as anemia, sickle cell disease, and bleeding disorders. Search the NIH RePORTer to learn about research the NHLBI is funding on blood transfusion.
  • We stimulate high-impact research. The NHLBI Strategic Vision highlights ways we may support research over the next decade.

Learn about exciting research areas the NHLBI is exploring to improve blood transfusion.

Participate in NHLBI Clinical Trials

We lead or sponsor many studies on blood transfusion. See whether you or someone you know is eligible to participate in our clinical trials.

Have you had a heart attack, and do you want to help improve strategies for blood transfusion?

The study is comparing two strategies for blood transfusions in heart attack patients who have anemia—whether to give a blood transfusion when the hemoglobin level is less than 10 g/dL, or to give blood only when the blood count is below 8 g/dL. To participate in this study, you must be at least 18 years old, have anemia, and be hospitalized for a heart attack. The study is located in New Brunswick, New Jersey.

Did you recently give birth to a very low birth weight infant?

The study is investigating how anemia and red blood cell transfusions affect oxygen levels in the digestive tract of very low birth weight infants. To participate in this study, your newborn must have had a very low birth weight and be within seven days of birth. The study is taking place in Atlanta, Georgia.

More Information

After reading our Blood Transfusion Health Topic, you may be interested in additional information found in the following resources.

Other resources
- Blood Transfusion