Classification and incidence of adverse events

Classification of transfusion-related adverse reactions and estimated incidence

Immunological acute (<24 hours)

Adverse event	Incidence*
Acute haemolytic transfusion reaction (AHTR)	1:76,000
Fatal acute haemolytic reaction	1:1.8 million
Febrile non-haemolytic transfusion reaction (FNHTR)	0.1%–1% (with universal leucocyte depletion)
Mild allergic reactions (urticarial/pruritis)	1%–3% of plasma containing components
Severe allergic reactions (anaphylaxis)	1:20,000–1:50,000
Transfusion-related acute lung injury (TRALI)	1:1,200–1:190,000
Transfusion-associated dyspnoea	0.4%–3.4%

Non-immunological acute (<24 hours)

Adverse event	Incidence*
Complications of massive transfusion	Variable
Non-immune mediated haemolysis (physical or chemical destruction of blood)	Rare
Transfusion transmitted bacterial infection (for clinically apparent reactions) due to platelets	Approximately 1:250,000 (in Australia)**
Transfusion transmitted bacterial infection (for clinically apparent reactions) due to red cells	Approximately 1:2.5 million (in Australia)**
Transfusion-associated circulatory overload (TACO)	1–2.7%

Immunological delayed (>24hours)

Adverse event	Incidence*
Delayed haemolytic transfusion reaction (DHTR)	1:500–1:10,000
Post-transfusion purpura (PTP)	Rare
Transfusion-associated graft versus host disease (TA-GVHD)	Rare
Alloimmunisation - RBC antigens	1%
Alloimmunisation - HLA antigens	10%
Transfusion-related immune modulation (TRIM)	Not known

Non-immunological delayed (>24hours)

Adverse event	Incidence*
Iron overload	Increased morbidity and mortality associated with cumulative doses of 20 or more units
Transfusion-transmissible infections	For incidence refer to risk estimates for transfusion-transmissible infections

* May be based on overseas data.

** Based on Lifeblood data.

Updated August 2025