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Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Acute haemolytic and febrile transfusion reactions

Haematology and transfusion · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Suspected acute haemolysis

Fever, rigors, pain, hypotension, dyspnoea, bleeding or dark urine during red-cell transfusion can be the first sign of an ABO error and is treated as life threatening until excluded.

Action: Stop the transfusion immediately, keep intravenous access with 0.9% sodium chloride through new tubing, call for senior help and assess ABCDE. Recheck patient and component identity at the bedside and urgently contact the transfusion laboratory. Return the pack and giving set as directed; send a new correctly labelled EDTA sample, blood cultures when sepsis is possible, urine and haemolysis, renal and coagulation tests. Support blood pressure and urine output, treat hyperkalaemia and DIC and involve critical care and renal teams early.

Synopsis

Recognise fever and haemolysis during transfusion, stop incompatible exposure immediately, exclude bacterial contamination and complete the clinical and laboratory reaction pathway.

  • First-line action for any potentially serious reaction is stop the transfusion; do not discard the component or giving set and do not flush residual blood into the patient.
  • Maintain venous access with 0.9% sodium chloride through new tubing, assess ABCDE and summon senior clinical and transfusion-laboratory help.
  • Acute haemolytic transfusion reaction is haemolysis within 24 hours, classically caused by ABO-incompatible red cells after an identification error.
  • Key symptoms are fever, rigors, infusion-site or loin pain, chest pain, anxiety, dyspnoea, hypotension, dark urine, oliguria and abnormal bleeding.
  • Recheck identity at the bedside immediately: patient wristband, verbal identifiers, prescription, compatibility label, donation number and component group.
  • Send a new post-reaction sample for repeat group, antibody screen, DAT and haemolysis testing; return the component and tubing according to local policy.
  • Investigate renal injury, potassium, coagulation and fibrinogen; severe intravascular haemolysis can cause hyperkalaemia, AKI and DIC.
  • A febrile non-haemolytic transfusion reaction is a diagnosis of exclusion after haemolysis, bacterial contamination and other serious reactions have been assessed.
  • Do not label fever as benign because it is mild at first; severity, associated symptoms and progression determine the investigation and treatment pathway.
  • If bacterial contamination is plausible, take patient blood cultures, culture the implicated component through the transfusion service and start sepsis antibiotics promptly after cultures.
  • Paracetamol may relieve an established uncomplicated febrile reaction after serious causes are excluded; routine premedication is not a substitute for diagnosis and may mask fever.
  • Report and document confirmed serious reactions, preserve antibody and special-requirement records and explain the event and future precautions to the patient.

Key red flags

Pain at the infusion site, chest, abdomen, loin or back with fever, anxiety or flushing can precede overt shock in acute haemolytic transfusion reaction.

Hypotension, tachycardia, dyspnoea, haemoglobinaemia, haemoglobinuria, oliguria or diffuse bleeding suggests severe intravascular haemolysis and DIC.

A temperature rise with severe rigors or shock must be managed for bacterial contamination as well as haemolysis until cultures and investigation clarify the cause.

Any mismatch between the patient identifiers, compatibility tag, prescription or donation number is a never-event signal requiring immediate laboratory and governance escalation.

An anaesthetised patient may show only hypotension, unexplained bleeding, haemoglobinuria or failure to maintain perfusion; absence of reported pain is not reassuring.

Investigation priorities

01
First-line: bedside identity and clerical checkFirst stepFirst line

Detect ABO-incompatible administration and prevent further wrong-patient exposure.

Management branches

Any significant acute reactionStop, support, identify

New fever, rigors, pain, dyspnoea, hypotension or bleeding develops during transfusion.

  1. Stop the component, maintain access with new saline tubing, assess ABCDE and call senior help.
  2. Recheck patient and unit identity and notify the transfusion laboratory, stating symptoms, timing and infused volume.
  3. Send the directed reaction samples and return the component and set; treat the emerging syndrome without waiting for classification.

Key medicines

ParacetamolFor an established uncomplicated febrile reaction after serious causes have been excluded, give 500 mg to 1 g orally or intravenously, repeated no more often than every 4 to 6 hours to a usual maximum of 4 g in 24 hours.Use a lower maximum, commonly 3 g daily or less under local policy, in adults below 50 kg, frailty, chronic alcohol excess, malnutrition or liver disease. Count combination products and do not give routine premedication to conceal recurrent fever.
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Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • British Society for Haematology acute transfusion reactions guidelineCurrent UK recognition, immediate management and laboratory investigation of acute reactions.
  • SHOT haemolytic transfusion reactions cumulative dataUK haemovigilance definitions, mechanisms and learning for acute and delayed haemolysis.
  • SHOT febrile, allergic and hypotensive reactions cumulative dataCurrent UK haemovigilance classification and patient-safety learning for febrile reactions.
  • SHOT pre-transfusion sampling processUK bedside identification controls that prevent ABO-incompatible transfusion.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom