The meta-analysis revealed that, compared to antihistamines alone, the combination of probiotics and antihistamines significantly improved the urticaria relief rate (URR) (odds ratio [OR] 2.90, 95% confidence interval [CI] 1.97 to 4.28, p < 0.00001) and interferon-gamma (IFN-γ) levels (mean difference [MD] 8.12, 95% CI 6.95 to 9.30, p < 0.00001). The gene discussed is IFNG; the disease is urticaria.