Febrile non-haemolytic reaction

Definition

Febrile reactions are characterised by a rise in temperature and/or other inflammatory symptoms such as rigors, myalgia or nausea. In some cases, they may require medical intervention.

The cause is not fully understood but is thought to be due to residual white cells in the unit or cytokines built up during storage.

Usually a reaction to a specific unit of blood component, it is difficult to mitigate against and often unpredictable.

Frequency

Mild: Common (≥1 in 100 to <1 in 10).

Moderate and severe: Rare (≥1 in 10,000 to <1 in 1,000).

Reducing the risk

Since the introduction of leucodepleted blood components, febrile reactions have become less common. Transfusing over a longer period or temporarily stopping the transfusion and/or giving paracetamol may help.

Only a small proportion of patients will experience recurrent febrile reactions. In such cases, giving prophylactic paracetamol may reduce the incidence.

Further information and resources

Serious Hazards of Transfusion (SHOT) resources:

• SHOT Bite No.5a: Febrile, Allergic and Hypotensive Reactions (FAHR) - Getting the diagnosis right (2021)
• Febrile, Allergic and Hypotensive Reactions (FAHR) cumulative data
• Febrile, Allergic and Hypotensive Reactions (FAHR) video

NHS Blood and Transplant (NHSBT) resources:

• Histocompatibility and Immunogenetics (H&I) diagnostic services user guide (PDF 1.1MB)

British Society for Haematology (BSH) guidelines:

• Guideline on the investigation and management of acute transfusion reactions (2023)