Food-additive-induced urticaria: a survey of 838 patients with recurrent chronic idiopathic urticaria

<i>Background:</i> Recurrent chronic idiopathic urticaria (RCIU) is a common skin condition that affects 0.1–3% of the population in the USA and Europe and accounts for nearly 75% of all ‘ordinary’ chronic urticaria (CU) cases. <i>Methods:</i> We studied 838 consecutive patients with RCIU referred to hospital between 1998 and 2003. Patients with known causes of CU were excluded. Clinical history, physical examination, and symptom diaries were evaluated during two periods, a diet-free period (1 week) and a food-additive-free diet (FAFD) period (4 weeks), respectively, and two double-blind placebo-controlled (DBPC) challenges of six food additives were administered. Th…