Abstract
BACKGROUND: Chronic urticaria, characterized by persistent hives and pruritus lasting over six weeks, often presents diagnostic and therapeutic challenges. While its etiology is frequently idiopathic, associations with nutritional deficiencies, such as vitamin B12 deficiency, have been observed. CASE PRESENTATION: A 24-year-old female with no significant medical history presented with chronic, treatment-resistant hives persisting for several years. Comprehensive evaluations, including allergy testing and autoimmune screenings, were unremarkable. Further investigation revealed a significant vitamin B12 deficiency (serum B12 level of 170 pg/mL), attributed to her long-standing vegan diet without supplementation. Initiation of vitamin B12 supplementation led to the gradual resolution of her chronic urticaria. CONCLUSION: This case underscores the importance of considering vitamin B12 deficiency in the differential diagnosis of chronic urticaria, especially in patients adhering to restrictive diets. Addressing nutritional deficiencies can be a straightforward and effective approach in resolving chronic urticaria symptoms.