The Role of Diet in the Management of Chronic Idiopathic Urticaria: A Scoping Review.

Chronic idiopathic urticaria (CIU) is a dermatologic condition characterized by recurrent wheals, angioedema, or both for more than six weeks in the absence of an identifiable trigger. It is driven by spontaneous mast cell activation and the release of inflammatory mediators in the skin. Given its poorly understood pathogenesis, significant morbidity, and limitations of available treatment modalities, studies have suggested a link between diet and CIU. The primary objective of this study was to evaluate the literature published from 2015 to 2025 on this link, with an emphasis on dietary interventions, patient-reported outcomes, and gaps in the existing knowledge base. We conducted a scoping review following PRISMA guidelines, utilizing databases such as EMBASE, OVID Medline, and Web of Science. Search terms related to urticaria included "chronic idiopathic urticaria," "chronic spontaneous urticaria," "chronic idiopathic/spontaneous urticaria," "CIU/CSU," "CSU/CIU," "spontaneous chronic urticaria," and "idiopathic chronic urticaria," combined with terms related to diet, including "diet," "diet influence," "diet regimen," and "dietary effect." The initial database search identified 121 records, of which nine met the eligibility criteria and eight were included after critical appraisal. The eight included studies examined the Mediterranean diet, a low-pseudoallergen diet, a pseudoallergen-free diet, a histamine-free, low-pseudoallergen diet, and a low-histamine diet, as well as micronutrient levels and inflammatory markers. The dietary interventions lasted from seven to slightly more than 39 days. The studies evaluated the effects of these diets on CIU disease activity, disease control, and quality of life using measures such as the Urticarial Activity Score, Urticarial Control Test, and Chronic Urticaria Quality of Life score. Outcomes tended to improve in the short term following the implementation of these diets, particularly in studies of diets limiting histamine and pseudoallergen intake. Additional findings included an association between CIU and a higher BMI. One study also reported higher vitamin D levels and lower vitamin B12 levels in patients with CIU than in the general population. The current body of literature is limited by small sample sizes, short intervention durations, and limited immunologic exploration. However, the consistency of patient-reported improvements across diverse geographic and dietary contexts underscores the potential role of diet as an adjunctive approach to CIU management. Future research should prioritize larger sample sizes, more balanced representation of the sexes, longer-term trials, and better control of participant-level confounding variables.