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Basil Allergy: IgE-Mediated Reactions, Cross-Reactivity, and Management

Basil (Ocimum basilicum) allergy is uncommon but well-documented, typically IgE-mediated with potential for systemic reactions. It falls under Lamiaceae (mint family) sensitization.

Clinical Manifestations

System Symptoms Onset
Cutaneous Urticaria, angioedema, pruritus, contact dermatitis (chefs/gardeners) Minutes–hours
Respiratory Rhinitis, conjunctivitis, wheezing, dyspnea, laryngeal edema Minutes
GI Nausea, vomiting, abdominal pain, diarrhea Minutes–2 hours
Systemic Anaphylaxis (hypotension, collapse, sense of doom) Minutes

Cross-Reactivity (Lamiaceae Family & Pollen-Food Syndrome)

  • Botanical family (Lamiaceae): Mint, oregano, thyme, rosemary, sage, lavender, marjoram, perilla — shared lipid transfer proteins (LTPs), profilins.
  • Pollen-food syndrome (PFAS): Mugwort (Artemisia) sensitization → cross-reactivity to basil, celery, carrot, spices (celery-mugwort-spice syndrome).
  • Profilin (Bet v 2 homolog): Pan-allergen; mild oral allergy syndrome (OAS) predominates.
  • LTP (Oc b 1, Pru p 3 homolog): Stable to heat/digestion; higher systemic risk.

Diagnosis

  • History: Timing, reproducibility, cofactors (exercise, alcohol, NSAIDs).
  • Skin prick test: Commercial extract or prick-prick with fresh basil.
  • Serum sIgE: Basil-specific (limited availability); component-resolved (rOc b 1 LTP, profilin).
  • Oral food challenge: Gold standard; blinded if possible.

Management

  • Avoidance: Read labels (pesto, sauces, dressings, herbal teas, supplements, cosmetics).
  • Antihistamines: Second-gen (cetirizine, fexofenadine) for mild cutaneous.
  • Epinephrine auto-injector: Prescribed if anaphylaxis history or LTP sensitization.
  • Cooking effect: Heat-labile allergens (profilin) destroyed; LTPs resistant — know your sensitizer.
  • Cross-reactive foods: Trial cautiously if mugwort-allergic.

Occupational Considerations

Chefs, gardeners, greenhouse workers: Higher risk for contact urticaria, rhinitis, asthma. Patch testing for contact dermatitis (different mechanism: type IV).

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