ABSTRACT
Introduction: The role of azo dyes in urticaria is not fully understood. Aim: To assess the incidence rate of hypersensitivity reactions to food azo dyes based on a placebo-controlled oral challenge in a group of patients with suspected urticaria exacerbation after consuming food additives. Material and methods: The study included patients over 18 years of age with chronic urticaria, in whom hypersensitivity to food additives was suspected based on a questionnaire and medical history. Patients suspected of urticaria exacerbations after ingestion of azo dyes were enrolled in a placebo-controlled single-blind oral challenge (OC) with a mixture of azo food dyes: tartrazine, Quinoline Yellow, Sunset Yellow, Cochineal Red, Allura Red, and azorubine. Results: Out of 110 patients (76 women and 34 men, mean age 46.1 (20-76 years), 39 patients were qualified for the oral challenge. We observed two subjects (5.1%) with a positive result. Conclusions: Azo dyes ingested in food or medications incidentally cause urticaria but may exacerbate its course. Oral challenge-confirmed hypersensitivity to azo dyes is much less common than reported by patients.
ABSTRACT
Introduction: Carmine, a commonly used natural red dye, can cause immediate and delayed allergic reactions, which are frequently overlooked. Aim: To assess the incidence of carmine allergy and its clinical significance based on the placebo-controlled oral challenge in urticaria patients and suspected hypersensitivity to food additives. Material and methods: Patients' histories were recorded by means of a standardized questionnaire. The subjects underwent skin prick tests and patch tests for carmine, while the level of specific IgE was measured in 52 patients. The patients with at least one positive carmine test or with suspected hypersensitivity to carmine were suggested to undergo a placebo-controlled oral challenge test. Results: One hundred and ten patients were enrolled in the study. Carmine skin testing was positive in 22 patients: skin prick tests were positive in 17% (n = 19), while patch tests were doubtful in 6% (n = 6). In 25/52 patients, the level of specific IgE was min. 0.01 kU/l. Oral challenge was performed in 33 subjects. Allergy to carmine was diagnosed in 9 (8%) patients; all of them suffered from chronic inducible urticaria. Conclusions: Carmine is a potential allergen in patients with chronic inducible urticaria especially with concomitant systemic symptoms. Skin tests and specific IgE level measurement may be helpful tools to diagnose E120 hypersensitivity.
