What are the common triggers that can cause anaphylaxis?

Common Triggers of Anaphylaxis

Foods are by far the most common triggers of anaphylaxis in the pediatric population, particularly peanuts, tree nuts, milk, eggs, crustacean shellfish, and finned fish. 1

Primary Triggers by Population

Pediatric Patients

• Foods dominate as triggers, specifically: 1
  • Peanuts
  • Tree nuts
  • Milk
  • Eggs
  • Crustacean shellfish
  • Finned fish

All Age Groups

• Medications are the most common cause of drug-induced anaphylaxis: 1, 2

  • Penicillin is the single most common drug trigger 1
  • Antibiotics (particularly beta-lactams and cephalosporins) 1
  • Aspirin and nonsteroidal anti-inflammatory drugs (medication-specific, do not cross-react with structurally unrelated compounds) 1

• Insect stings (particularly hymenoptera venom) 1, 2

• Various other allergens including environmental exposures 1

Anesthesia-Related Triggers

• Neuromuscular blocking agents 1
• Chlorhexidine (used as antiseptic for procedures, catheter coatings) 1
• Latex 1
• Antibiotics administered perioperatively 1
• Protamine, heparins, aprotinin, radiological contrast material 1

Important Cofactors That Lower the Threshold

These cofactors do not cause anaphylaxis alone but significantly increase risk when combined with allergen exposure: 1

• Exercise 1
• Upper respiratory tract infections 1
• Fever 1
• Nonsteroidal anti-inflammatory drug ingestion 1
• Alcohol (ethanol) consumption 1
• Emotional stress 1
• Perimenstrual status 1

Critical Clinical Pitfalls

Vaccinations Rarely Trigger Anaphylaxis

• Despite common concerns, vaccinations to prevent infectious diseases seldom trigger anaphylaxis 1

Idiopathic Anaphylaxis

• Unidentified triggers occur in up to one-fifth of cases 2
• Many cases labeled "idiopathic" may actually represent "summation anaphylaxis" where the allergen alone is insufficient but combined with cofactors (infection, exercise, stress, medications like beta-blockers) triggers the reaction 3

High-Risk Scenarios for Severe or Fatal Reactions

The following patient characteristics and triggers are associated with increased mortality: 1, 2

• Adolescence 1
• Concomitant asthma, especially if severe or poorly controlled 1, 2
• Peanut and tree nut allergy 2
• Drug-induced reactions 2
• Underlying cardiovascular disease 2
• Mast cell disorders 2
• Older age 2
• Failure to inject epinephrine promptly 1

Anesthesia-Specific Considerations

• Asthmatic smokers with multiple prior antibiotic courses are at highest risk for anaphylaxis to amoxicillin and cephalosporins, and symptoms are likely to be initially misinterpreted as expected anesthetic complications 1
• Cutaneous sensitivity to cosmetics or rashes from cough medicines may indicate cross-reactivity with quaternary ammonium groups found in opioids and muscle relaxants 1

Mechanistic Categories

IgE-Mediated (True Anaphylaxis)

• Requires prior sensitization period 1, 4
• Most drugs must combine with carrier proteins to form immunogenic antigens 1
• Represents Type I hypersensitivity reaction 4

Non-IgE-Mediated (Anaphylactoid)

• Direct mast cell degranulation without prior sensitization 1, 5
• Can occur on first exposure 1
• Clinically indistinguishable from IgE-mediated reactions 4
• Alternative activation pathways include toll-like receptors, complement receptors, or Mas-related G-protein-coupled receptors 5