Case Report: Not all recurrent "idiopathic" anaphylaxis is idiopathic.

Introduction: Anaphylaxis is the most severe manifestation of systemic immediate hypersensitivity, yet the underlying trigger often remains elusive. When routine history and allergy testing fail to identify a cause, the condition is classified as idiopathic anaphylaxis. Food additives, although uncommon culprits, may be overlooked, particularly in atopic individuals. Methods: We report a case of a 39-year-old woman with recurrent anaphylaxis initially diagnosed as idiopathic. Standard allergy testing, including extended skin prick and specific IgE panels, was negative. Due to a temporal association with restaurant-prepared food, an additive hypersensitivity was suspected. A detailed dietary history and targeted skin prick testing were employed using both commercial and in-house preparations of food colorants. Results: SPT was positive for carmine-containing red food colorants, including a commercially available gel and a prepared cochineal extract. Control subjects tested negative. sIgE to carmine was equivocal. The patient was educated about allergen avoidance and has remained symptom-free following elimination of carmine from her diet, cosmetics, and medications. Conclusion: This case underscores the importance of considering food additives, particularly carmine, in patients with unexplained anaphylaxis. Structured re-evaluation, patient-guided dietary review, and custom allergen testing may be essential in identifying hidden allergens. Clinicians should be vigilant about uncommon triggers when routine investigations fail to identify the cause.