Anaphylaxis is triggered by a single allergen in 80% of cases, but in 20% cases, the primary allergen may not be so clear. Certain factors promote anaphylaxis occurring and make reactions more intense.

These trigger factors include: 

  • Exercise (as in food-dependent exercise-induced anaphylaxis (FDEIA) as occurs with exercising shortly      after meals containing  wheat, shellfish, meat, spinach and pistachio.
  • Intake of non-steroidal anti-inflammatory drugs (such as aspirin and ibuprofen)
  • Other drugs such as iodinated radio-contrast,  anaesthetic muscle relaxants, morphine-related opiates and DNA gyrase inhibitor antibiotics (called quinolones).
  • Drugs for heartburn and reflux such as the H2 blocker Ranitidine and Proton Pump Inhibitor PPIs (omeprazole & lanzoprazole), reduce gastric acid and allow allergens to penetrate the GI more deeply and intact, making an allergic response more likely.
  • Alcohol non-specifically increases anaphylaxis risk by speeding metabolism.
  • Infectious diseases such as non-specific viral and bacterial infections can act as anaphylactogenic cofactors.

Reference: Wolbing F, Fischer J, Kaesler S. About the role and underlying mechanisms of cofactors in anaphylaxis. Allergy; 2 August 2013