anaphylactoid reaction

Introduction

Clinically similar to anaphylaxis, but due to non-immunologic (i.e. not IgE-mediated) mast cell degranulation.

Etiology

• complement-mediated mast cell degranulation
• reactions to radiographic dyes (contrast agents)
• reactions to aspirin
• pharmaceutical agents with direct effect on mast cells resulting in degranulation
  • polymixin, opiates, tubocurarine, thiamine, pentamidine, hydralazine, daunorubicin

Clinical manifestations

• anaphylactoid reaction due to aspirin or NSAIDs
  • triad of rhinosinusitis, nasal polyps, asthma

Diagnostic procedures

• skin testing not available

Management

• see anaphylaxis
• for reactions to radiographic contrast agents
  • low osmolarity contrast agents
  • pretreatment with
    • prednisone
    • histamine-H1-receptor antagonist

More general terms

• sign/symptom

Additional terms

• adverse drug reaction (ADR)
• anaphylaxis