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Haematology & Oncology

Transfusion Reactions

Blood components injure recipients four separate ways, immune destruction of red cells, plasma-protein allergy, bacterial contamination and sheer transfused volume, and at onset they look alike.

In a nutshell

A transfusion reaction is any adverse event during a transfusion or within 24 hours of it. Stop the transfusion, keep the vein open with 0.9% sodium chloride, check the patient against the compatibility label, and grade the reaction on the temperature rise.

Classic presentation

Fifteen minutes into a red cell transfusion, a patient develops rigors, loin pain, hypotension and dark urine: recheck the wristband for an ABO-incompatible transfusion, the wrong blood group.

Key points

  • Most reactions begin within the first 15 minutes, which is why observations are repeated at 15 minutes as well as before and after each unit.
  • Give intramuscular adrenaline even if the patient is thrombocytopenic or anticoagulated. The bleeding risk does not outweigh untreated anaphylaxis.
  • Skin-only reactions need no repeat compatibility testing. The laboratory work-up for a febrile reaction and for an allergic one are not the same.
  • Transfusion-associated graft-versus-host disease appears within 30 days, when viable donor lymphocytes engraft and expand in the recipient.
  • A hypotensive reaction is an isolated systolic fall of 30 mmHg or more to 80 mmHg or less; stop an angiotensin-converting enzyme (ACE) inhibitor before the next transfusion.
  • Immunoglobulin A (IgA) below 0.07 g/L after anaphylaxis means washed components for elective transfusion, but never delay a life-saving transfusion to obtain them.

First-line investigation

Bedside identity check of patient, wristband and compatibility label, plus temperature, pulse, blood pressure and respiratory rate compared with the pre-transfusion baseline.

Management

Stop, check, grade

  • Stop the transfusion. Keep the cannula open with 0.9% sodium chloride through a new giving set, and assess airway, breathing, circulation, disability and exposure (ABCDE).1
  • Check patient, wristband and compatibility label against each other and inspect the unit. Telephone the transfusion laboratory at once if an ABO mismatch is possible.1
  • Grade on the thermometer: above 38°C with a 1 to 2°C rise and nothing else, or rash alone, is mild. Fever 39°C or over, a 2°C rise or rigors is not.1,2
  • Repeat full observations. Baseline is taken within 60 minutes before starting, then again within the first 15 minutes, then within 60 minutes of finishing each unit.5

Treat the reaction you have graded

  • Mild fever: paracetamol 500 mg to 1 g orally, every 4 to 6 hours, maximum 4 g in 24 hours. Restart the unit under direct observation.1,10
  • Mild allergy: slow the transfusion and give chlorphenamine 10 mg intramuscularly or by slow intravenous injection, or 4 mg orally every 4 to 6 hours.1,11
  • Anaphylaxis: adrenaline 500 micrograms IM (0.5 mL of 1 in 1000) into the anterolateral middle third of the thigh, repeated every 5 minutes until improvement.1,7,12
  • Then lie flat with legs raised, high-flow oxygen, rapid crystalloid 500 to 1000 mL, and nebulised salbutamol 5 mg for wheeze. Corticosteroids are not routine.1,7,13,14

Haemolysis, contamination and the lungs

  • Fever 39°C or over with rigors or shock: take blood cultures. Start source-appropriate broad-spectrum IV antibiotics within 1 hour, following local sepsis and microbiology guidance.1,15
  • Isotonic crystalloid, Hartmann's or 0.9% sodium chloride, in 250 mL boluses over 10 to 15 minutes, up to 1000 mL total, reassessing after each bolus.15
  • TACO, oedema within 12 hours with fluid overload: sit up, oxygen, furosemide 20 to 50 mg by slow IV injection, maximum 4 mg per minute. No guideline gives a TACO-specific dose.2,16,1
  • TRALI, hypoxia within 6 hours without overload: oxygen and ventilatory support. A loop diuretic can worsen it. Discuss with the blood service so donors can be investigated.1,2,4

Investigate the reaction

  • Return the unit and giving set. Send FBC, renal and liver enzymes, repeat compatibility testing, direct antiglobulin test on pre- and post-transfusion samples, haptoglobin, lactate dehydrogenase and coagulation.1
  • Send urine for haemoglobin and blood cultures if fever is sustained. Chest radiograph for any respiratory symptom not explained by allergy.1
  • After anaphylaxis: mast cell tryptase as soon as feasible, at 1 to 2 hours and at 24 hours, plus immunoglobulin A. No result changes what you do now.1,7,9

Report, then plan the next transfusion

  • Report moderate and severe reactions to the Medicines and Healthcare products Regulatory Agency (MHRA) through Serious Adverse Blood Reactions and Events (SABRE). This is a legal duty.1,2
  • Reporting to Serious Hazards of Transfusion (SHOT), the UK haemovigilance scheme, is professionally mandated. Mild febrile and mild allergic reactions are not SHOT-reportable.1,2
  • Record any new red cell antibody permanently and use antigen-negative units afterwards. Recurrent febrile reactions: oral paracetamol 60 minutes before the expected reaction, then washed components.1,8,10
  • Delayed haemolysis is fever, jaundice or a falling haemoglobin beyond 24 hours. Post-transfusion purpura at 5 to 12 days is treated with intravenous immunoglobulin.2,17

Exam traps

  • Transfusion-associated circulatory overload (TACO), plain fluid overload, causes more UK transfusion deaths than haemolysis. Exams favour ABO errors; the mortality data do not.
  • The 6-hour window belongs to transfusion-related acute lung injury (TRALI). TACO runs to 12 hours, and transfusion-associated dyspnoea to 24 hours.
  • A loop diuretic helps TACO and can worsen TRALI, so decide which you are treating before you prescribe it.
  • Corticosteroids act on the late-phase response and do not treat the acute reaction. Chlorphenamine treats skin, never airway or circulation.
  • A mild reaction can be treated and the same unit restarted under direct observation. Stopping every reaction permanently is not what the guideline says.
  • Hypotension during a transfusion for major haemorrhage may be the bleeding, not the blood. Stopping the transfusion there can be the fatal move.

Illustrations

Transfusion-related acute lung injury on chest radiographyPaired chest radiographs showing diffuse bilateral air-space opacity during transfusion-related acute lung injury and subsequent clearing after recovery.Altaf Gauhar Haji, Shekhar Sharma, DK Vijaykumar and Jerry Paul, Wikimedia Commons · CC-BY-2.0

Key sources

  1. British Society for Haematology, Guideline on the investigation and management of acute transfusion reactions (Soutar R et al, Br J Haematol 2023, doi 10.1111/bjh.18789. States the mild/moderate severity thresholds, maintaining venous access with physiological saline, paracetamol 500 to 1000 mg for mild febrile reactions, chlorphenamine 10 mg, adrenaline 500 micrograms intramuscularly into the anterolateral middle third of the thigh, the 500 to 1000 mL crystalloid challenge, the loop diuretic caution in TRALI, and the MHRA and SHOT reporting duties. For suspected bacterial contamination it advises the antibiotic regimen a unit would use for neutropenic sepsis, without naming a drug. The full text sits behind the publisher and cannot be opened by an automated checker; this landing page is the guideline's official home. Published 26 April 2023, last reviewed 12 July 2023)Published 26 Apr 2023 | Updated 12 Jul 2023
  2. Serious Hazards of Transfusion (SHOT), Definitions of current SHOT reporting categories and what to report, January 2026 (Page 15: febrile, allergic and hypotensive reactions occur at any time up to 24 hours after transfusion. Page 16: the mild, moderate and severe grading table, including the hypotensive reaction definition. Page 17: acute versus delayed haemolytic reaction at 24 hours. Page 18: post-transfusion purpura at 5 to 12 days. Page 19: graft-versus-host disease less than 30 days after transfusion. Page 20: TACO during or up to 12 hours, requiring criterion A and/or B plus at least three of the five criteria in total, with NT-proBNP above 1.5 times the pre-transfusion value as supportive criterion E. Page 21: transfusion-associated dyspnoea within 24 hours, TRALI during or within 6 hours)Published 1 Jan 2026 | Updated 1 Feb 2026
  3. SHOT, Chapter 21a, Transfusion-associated circulatory overload, Annual SHOT Report 2025 (214 TACO cases in 2025, the highest to date; TACO mortality accounted for 44.4% of all transfusion-related deaths reported; pre-transfusion TACO risk assessment is not consistently used)Updated 10 Jul 2026
  4. SHOT, Chapter 21, Pulmonary complications of transfusion, Annual SHOT Report 2025 (Pulmonary complications remain the largest category of transfusion-associated mortality; TRALI remains rare, with 5 cases in 2025 and none associated with leucocyte antibodies)Updated 10 Jul 2026
  5. NHS Blood and Transplant, Blood Essentials, version 2.0 (Section 5.10: baseline observations within the 60 minutes before transfusion, further observations within the first 15 minutes of starting, and post-transfusion observations within 60 minutes of completing, for every unit. Section 6.1: the risk of serious harm from a blood component is about 1 in 15,450 units transfused and the risk of death about 1 in 63,537 units. Section 6.5.3: most reactions occur within the first 15 minutes)Published 1 Jun 2025 | Updated 1 Jun 2025
  6. NICE NG24, Blood transfusion (Section 1.7, Patient safety, recommendations 1.7.1 and 1.7.2: monitor the patient's condition and vital signs before, during and after blood transfusions, to detect acute transfusion reactions that may need immediate investigation and treatment; and observe patients who are having or have had a blood transfusion in a suitable environment with staff who are able to monitor and manage acute reactions. NG24 states no observation schedule and no bedside identity check. Last updated 26 February 2026)Published 18 Nov 2015 | Updated 26 Feb 2026
  7. Resuscitation Council UK, Emergency treatment of anaphylaxis: guidelines for healthcare providers (Resuscitation Council UK guideline, May 2021: adrenaline 500 micrograms intramuscularly, 0.5 mL of 1 mg/mL (1 in 1000), into the anterolateral aspect of the middle third of the thigh, repeated after 5 minutes if there is no improvement; the patient kept flat with the legs raised; a rapid intravenous crystalloid bolus of 500 to 1000 mL in an adult; salbutamol as a further bronchodilator; corticosteroids no longer advised routinely. Section 7.2, sample timing: three timed mast cell tryptase samples, an initial sample as soon as feasible, a second 1 to 2 hours after the onset of symptoms, and a third at least 24 hours after complete resolution or in convalescence)Published 1 May 2021
  8. SHOT, Chapter 20, Febrile, allergic and hypotensive reactions, Annual SHOT Report 2025 (Table 20.3, targeted treatment: paracetamol for a febrile reaction, and paracetamol 60 minutes before the anticipated time of the reaction to prevent recurrent febrile reactions. Of 7 reactions in patients later found to have severe IgA deficiency, 5 were febrile or inflammatory and 3 began within the first 15 minutes. Table 20.1 reproduces the IHN/SHOT/BSH severity classification)Updated 10 Jul 2026
  9. NHS Blood and Transplant, Investigation and clinical management of suspected reactions to immunoglobulin A (IgA), INF486/1.6 (Selective IgA deficiency is defined by the European Society for Immunodeficiencies as a serum IgA level below 0.07 g/L with normal serum IgG and IgM, once other causes of hypogammaglobulinaemia are excluded. IgA screening is indicated when investigating an acute allergic or anaphylactic transfusion reaction. Washed components require NHSBT consultant authorisation, and urgent treatment must not be denied or delayed because IgA deficient components are not immediately available. Effective 23 January 2023)Published 23 Jan 2023
  10. BNF, Paracetamol (BNF monograph: adult 0.5 to 1 g by mouth every 4 to 6 hours, maximum 4 g per day)
  11. BNF, Chlorphenamine maleate (BNF monograph: adult 10 mg by intramuscular or intravenous injection, repeated if necessary to a maximum of 4 doses per day, given intravenously over 1 minute; adult 4 mg by mouth every 4 to 6 hours)
  12. BNF, Adrenaline (BNF monograph, emergency treatment of acute anaphylaxis: adult 500 micrograms by intramuscular injection using adrenaline 1 in 1000 (1 mg/mL), repeat after 5 minutes if no response, injected preferably into the anterolateral aspect of the middle third of the thigh)
  13. BNF, Salbutamol (BNF monograph: adult 2.5 to 5 mg by inhalation of nebulised solution, given via an oxygen-driven nebuliser where available)
  14. BNF, Hydrocortisone (BNF monograph: adult 100 to 300 mg by intravenous injection as sodium succinate, as an adjunct to adrenaline in acute hypersensitivity reactions. Retained in the BNF but not advised routinely by the British Society for Haematology)
  15. NICE NG253, Suspected sepsis in people aged 16 or over: recognition, assessment and early management (Section on managing suspected sepsis: broad-spectrum intravenous antibiotics within 1 hour for people at high risk; an intravenous fluid bolus within 1 hour, using an isotonic crystalloid (a balanced solution such as Hartmann's, or 0.9% saline), an initial 250 mL bolus over 10 to 15 minutes, further 250 mL boluses up to 1000 mL total, reassessing after each)Published 19 Nov 2025 | Updated 5 Dec 2025
  16. BNF, Furosemide (BNF monograph, oedema: adult initially 20 to 50 mg for one dose by slow intravenous injection, then increased in steps of 20 mg every 2 hours if required; doses above 50 mg by intravenous infusion only; intravenous administration rate should not usually exceed 4 mg per minute)
  17. British Society for Haematology, Guidelines for the use of platelet transfusions (Estcourt L et al, Br J Haematol 2017. Recommendation: in post-transfusion purpura, intravenous immunoglobulin is the treatment of choice (1C), given without waiting for laboratory confirmation, with random donor platelets reserved for severe bleeding. Published 23 December 2016, last reviewed 14 January 2022)Published 23 Dec 2016 | Updated 14 Jan 2022

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.