Transfusion medicine
Transfusion reaction
Allergic and anaphylactic transfusion reaction

Topic Completed: 1 September 2011

Revised: 5 April 2019

Copyright: 2002-2019,, Inc.

PubMed Search: Allergic and anaphylactic transfusion reaction

Huy Phu Pham, M.D., M.P.H.
Page views in 2018: 2,166
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Cite this page: Pham HP Allergic and anaphylactic transfusion reaction. website. Accessed June 25th, 2019.
Definition / general
  • Allergic transfusion is most common transfusion reaction - occurs in all types of product but less common with pRBCs
  • Most reactions are mild; occur in 0.03 - 0.61% of pRBC transfusions, 0.3 - 6% of platelet transfusions, 1 - 3% of plasma transfusion
  • Anaphylactic reactions occur in 1:20,000 to 1:47,000 components transfused
  • May also occur in autologous transfusions (Arch Pathol Lab Med 2003;127:316)
  • Anaphylactic reactions associated with IgA deficiency or haptoglobin deficiency, especially in Asian patients; incidence 1:1,000 recipients
  • Much of the pathophysiology is still unknown
  • Type I hypersensitivity reaction
    • Allegen (usually a protein in the plasma of the transfused product) binds to cell-associated IgE → activation of mast cells → release of mediators (cytokines, histamines, leukotrienes, Curr Opin Hematol 2003;10:419)
  • Anti-IgA
    • Patients with congenital IgA deficiency may develop anti-IgA antibodies; exposure to IgA can lead to anaphylactic reaction
    • 1:500 blood donors are IgA deficient, and 1:1,200 blood donors have anti-IgA antibodies but most are not at risk of an anaphylactic transfusion reaction (Immunohematol 2004;20:226)
  • Antibodies to other normal plasma proteins
    • Patients with antibodies to other plasma proteins, such as haptoglobin, C3 / C4, alpha-1-antitrypsin, can also have anaphylactic transfusion reactions
  • Components within blood products
    • Transfusion of the allergen which the patient has an antibody against or the antibody which the patient has an allergen for can lead to anaphylactic transfusion reactions
Clinical features
  • The sooner the onset of symptoms from transfusion, the more severe the reaction (in general)
  • Anaphylactic reactions tend to happen from within seconds to 45 minutes after the start of the transfusion
  • Other allergic reactions can occur up to 2 - 3 hours after completion of the transfusion
  • Mild allergic reaction:
    • No fever
    • Pruritis, uticaria, erythema, cutaneous flushing, angioedema, nausea, vomiting, diarrhea, abdominal pain
    • 10% have only pulmonary symptoms
  • Anaphylactic reaction:
    • Symptoms of allergic reactions plus hypotension, tachycardia, chest pain, loss of consciousness, arrhythmia, shock, cardiac arrest, wheezing
    • No fever
    • Patient can have upper and lower airway obstruction → hoarseness, stridor, dypsnea
  • Mostly a clinical diagnosis
  • In patients with severe allergic or anaphylactic transfusion reaction, test for IgA deficiency and anti-IgA antibody; test for haptoglobin deficiency and antibody in Asian patients
Case reports
  • Mild allergic reaction:
    • Temporarily stop the transfusion
    • Maintain IV access
    • Give diphenhydramine 20 - 50 mg PO or IV (depending on the severity)
    • If the symptoms resolve, restart the transfusion slowly
    • If the symptoms do NOT resolve, stop the transfusion
    • Always report the reaction to the transfusion medicine service even when the transfusion continues
  • Severe allergic or anaphylactic reaction:
    • Stop the transfusion
    • Maintain IV access with normal saline
    • Administer oxygen
    • Intubation may be needed
    • Epinephrine is most effective medication for treatment of anaphylaxis
    • Steroid and H1 receptor antagonists have been used
    • Observe the patient closely
    • Report the reaction to the transfusion medicine service
  • In patients without prior history of allergic reaction:
  • In patients with prior history of allergic reaction:
    • Predmedication with diphenhydramine or steroids may be helpful, depending on the severity of the previous reaction
    • Allergic reactions tend to be more severe with repeated plasma / platelet transfusions
    • In patients with severe reaction, use of washed or plasma reduced pRBCs or platelets might be considered
      • Transfuse slowly
      • Observe patient closely
      • Appropriate medications and equipment should be available
  • In patients with IgA deficiency:
    • It is NOT necessary to restrict patients with IgA deficiency or anti-IgA antibodies to washed or IgA deficient products, WITHOUT a trial of unmodified products
    • Transfuse slowly
    • Observe closely for severe reaction
    • Appropriate medications and equipment should be available to treat if severe reaction occurs
  • In patients with IgA deficiency AND history of anaphylactic reaction:
    • May need to receive IgA deficient products (from IgA deficient donors) or washed products
    • Resuspending platelets in a nonprotein storage solution instead of fresh frozen plasma may be helpful (Transfusion 2002;42:556)
    • Autologous donation can be considered
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