Classification & incidence of adverse events

Each blood product transfused carries a small risk of an adverse effect.

Fever, chills and urticaria are the most common manifestations of transfusion reactions.

Potentially significant and life-threatening reactions include acute and delayed haemolytic transfusion reactions, transfusion transmitted bacterial infection (TTBI), anaphylaxis and Transfusion-related acute lung injury (TRALI).

It is important to recognise, respond to and report adverse events.

Once you recognise an adverse reaction, follow the steps for managing suspected transfusion reactions.

Classification of Transfusion-related Adverse Reactions and Estimated Incidence

Adverse event Incidence*
Haemolytic acute 1:76 000c
Haemolytic fatal 1:1.8 millionc
Febrile non-haemolytic transfusion reactions 0.1%–1% of transfusions with universal leucocyte depletionc
Mild allergic reactions (urticarial) 1%–3% of transfusionsc
Severe allergic reactions (anaphylaxis) 1:20 000–1:50 000b,c
Transfusion-related acute lung injury (TRALI) 1:1200–1:190 000c
Adverse event Incidence*
Complications of massive transfusion Variablec,d
Non-immune mediated haemolysis (physical or chemical destruction of blood) Rarec
Transfusion transmitted bacterial infection (for clinically apparent reactions) due to platelets At least 1:75 000a
Transfusion transmitted bacterial infection (for clinically apparent reactions) due to red cells At least 1:500 000b
Transfusion-associated circulatory overload (TACO) Less than 1% of patientsc
Adverse event Incidence*
Iron overload requiring chelation therapy May occur after 10–20 RBC unitse
Iron overload with organ dysfunction May occur after 50-100 RBC unitsc
Transfusion-transmissible infections For incidence rates refer to risk estimates for transfusion-transmissible infections

     Note: *Includes overseas data. Risks per unit transfused unless specified.


a. Eder et al. Bacterial screening of apheresis platelets and the residual risk of septic transfusion reactions: the American Red Cross experience (2004-2006). Transfusion 2007;47:1134–1142.

b. Kuenert MJ et al. Transfusion-transmitted bacterial infection in the United States, 1998 through 2000. Transfusion 2001;41:1493–1499.

c. Fung MK (ed). Non-infectious complications of blood transfusion. Chapter 27, AABB Technical Manual. 18th edition. AABB, Bethesda, 2014.

d. Popovsky M (ed). Transfusion reactions, 3rd edition. AABB Press, Bethesda, 2007.

e. Brittenham GM. Iron-chelating therapy for transfusional iron overload. New England Journal of Medicine 2011 Jan 13;364(2):146–156.