Blood transfusion is a common procedure that usually goes without complications. But there are some risks. Some transfusion reactions happen during the transfusion, while others may take several weeks to develop or become noticeable.

Allergic reaction and hives

Even though you'll be given blood that matches your blood type, it's still possible that you could have an allergic reaction to parts of the transfused blood. Signs and symptoms are usually limited to hives and itching. These types of transfusion reactions are usually treated with antihistamines and are seldom serious. Rarely, a more serious allergic reaction may occur and signs and symptoms may include difficulty breathing, low blood pressure, anxiety, rapid heartbeat and nausea.


When a fever develops quickly during the transfusion or soon after, it may be what's called a febrile reaction. Fever usually isn't serious. But because fevers can be a sign of a serious reaction, if you develop one during a transfusion your doctor will stop the transfusion to do further tests before deciding whether to continue. Fever may be accompanied by chills and shaking.

Acute immune hemolytic reaction

This is a very rare but serious transfusion reaction in which your body attacks the transfused red blood cells because the donor blood type is not a proper match. In response to the attack, the transfused red blood cells release a substance into your blood that harms your kidneys. This usually occurs during or right after a transfusion. Signs and symptoms include fever, nausea, chills, lower back or chest pain, and dark urine.

Lung injury

Transfusion-related acute lung injury (TRALI) is thought to occur due to antibodies or other biologic substances in the blood components. With TRALI, the lungs become damaged, making it difficult to breathe. Usually, TRALI occurs within one to six hours of the transfusion. People usually recover, especially when treated quickly. Most people who die after TRALI were very sick before the transfusion.

Bloodborne infections

Blood banks screen donors for risk factors and test donated blood to reduce the risk of transfusion-related infections, but they occasionally still occur. It can take weeks or months after a blood transfusion to determine that you've been infected with a virus, bacterium or parasite.

Estimated risks of contracting these diseases after you receive a blood transfusion:

  • HIV — 1 in 2.3 million transfusions.
  • Human T-lymphotropic virus — 1 of every 2 million transfusions.
  • Hepatitis B — 1 in 350,000 transfusions.
  • Hepatitis C affects — 1 in 2 million transfusions.
  • West Nile virus — 1 of every 350,000 units of blood in the United States.
  • Sepsis (bacterial infection of the blood) — 1 in 1 million transfusions.

Delayed hemolytic reaction

This is similar to acute immune hemolytic reaction, but it occurs much more slowly. Your body attacks the donor red blood cells, but at such a slow rate that it can take a while — often one to four weeks — to notice a decrease in red blood cell levels.

Iron overload

Multiple blood transfusions may lead to too much iron in your blood. This can damage parts of your body, including the liver and heart. People with iron overload (hemochromatosis) may be treated with iron chelation therapy, which uses medication to remove excess iron.

Graft-versus-host disease

When white blood cells in the donor blood attack the cells in your body, it's called transfusion-associated graft-versus-host disease. This disease is often fatal. It's also a very rare condition that's more likely to affect people with severely weakened immune systems, such as those being treated for leukemia or lymphoma. Signs and symptoms include fever, rash, diarrhea and abnormal liver function test results.

Apr. 26, 2012