Fluid‐Restricted Intermittent Fasting Improves Disease Control and Activity in Chronic Spontaneous Urticaria

Background Dietary strategies in chronic spontaneous urticaria (CSU) have primarily focused on restriction‐based interventions. The potential role of fluid‐restricted intermittent fasting (IF), which may exert immunomodulatory effects, remains underexplored in CSU. This study investigates the efficacy of IF as an adjunctive approach in patients with CSU. Methods In this prospective observational study, 100 patients with CSU on stable guideline‐directed treatment were allocated based on patient preference to a fasting group ( n = 50, following daily fluid‐restricted IF, median 15.5 h) or a nonfasting control group ( n = 50) for one month. Disease control and activity were assessed using the urticaria control test (UCT) and urticaria activity score (UAS). Results The fasting group achieved significantly higher UCT scores at one month compared to controls (13 vs. 12, p = 0.001). The change in UCT (ΔUCT) was significantly greater in the fasting group ( p < 0.001). While UAS decreased within the fasting group ( p < 0.001), the between‐group difference in ΔUAS was not significant. Multivariable regression confirmed fasting status as an independent predictor of improved control. Notably, significant improvements were observed even in patients with features of refractory disease, such as elevated CRP and eosinopenia. ROC analysis identified a 16‐h daily fasting threshold for optimal clinical improvement. Conclusions A structured, prolonged daily fasting regimen is associated with significant improvements in CSU disease control, including in patients with refractory profiles. IF may serve as a practical adjunct to standard therapies.