A blood transfusion is a procedure during which donated blood is added to your own blood in your body.Blood transfusions boost blood levels that are low.You may need a blood transfusion due to surgery, bleeding, injury, cancer, infection, a blood disorder, a liver problem, or another type of health concern.Blood contains components such as red blood cells, white blood cells, plasma, and platelets.A blood transfusion may provide you with whole blood, or with the parts of blood that are most helpful to you.Sometimes a blood transfusion is performed with your own blood that you’ve donated ahead of time.The blood given in a transfusion must be compatible with your blood type. Your blood will be tested to determine if it’s A, B, AB, or O, and if it’s Rh positive or Rh negative.Blood banks carefully screen donated blood to identify blood type.They also test for infectious diseases such as human immunodeficiency virus (HIV), which can be transmitted during a transfusion.More than 4.5 million Americans need a blood transfusion each year.Blood Transfusion ProcedureBlood transfusions are typically performed in a hospital, doctor’s office, or other medical facility.First, an intravenous (IV) line is placed in a vein, typically in an arm. Then blood or blood components that are stored in a plastic bag are delivered through the IV into your bloodstream.The blood transfusion typically takes one to four hours.Tell your doctor or nurse immediately if you experience any of the following symptoms during your transfusion:Shortness of breathFever or chillsPain at the infusion siteUnusual itchingA sense of uneasinessBefore a Blood TransfusionYou won’t need to change your diet or limit any activities before receiving a blood transfusion.Let your doctor know if you’ve had a transfusion in the past that caused an adverse reaction.After a Blood TransfusionAfter the blood transfusion procedure, you may develop bruising where the needle was inserted.You may need more blood testing to check how your body is responding to the transfusion.Blood Transfusion RisksBlood transfusions are considered safe, but certain complications can happen during or after the procedure. These include:Allergic reaction (anaphylaxis)FeverLung injuryAcute immune hemolytic reaction (occurs when the body suddenly attacks donor red blood cells)Delayed hemolytic reaction (occurs when the body gradually attacks donor red blood cells)Bloodborne infections such as HIV, hepatitis B, or hepatitis CIron overload (too much iron in the blood), often the result of repeated blood transfusionsGraft-versus-host disease (occurs when donor white blood cells attack the recipient’s bone marrow); this is very rare, typically occurring in immunocompromised patients