BACKGROUND: The pathogenesis of chronic spontaneous urticaria involves metabolic, immunological, and psychological factors. The thiol-disulfide exchange reactions could be a mechanism to counteract oxidative stress in patients with chronic spontaneous urticaria. OBJECTIVE: The assessment of thiol-disulfide homeostasis parameters (TDHPs) according to disease severity and the influence of H1-antihistamine therapy in patients with chronic spontaneous urticaria. MATERIAL AND METHOD: We have included 30 patients with chronic spontaneous urticaria in the study and we have determined the levels of native thiol, total thiol, disulfides as well as the disulfide/native thiol ratio, disulfide/total thiol ratio and the native thiol/total thiol ratio, before and after therapy with H1-antihistamines. RESULTS: The results of the study showed altered levels of TDHPs and their normalization after treatment with H1-antihistamines in patients with chronic spontaneous urticaria. We determined a statistically significant increase in the serum levels of total thiol, native thiol, and native thiol/total thiol ratio and a significant reduction in the levels of disulfides, disulfide/native thiol ratio and disulfide/total thiol ratio after treatment with H1-antihistamines. The normalization of the serum levels of TDHPs has been associated with the relief of symptoms and reduction or resolution of pruritus and urticarial plaques. CONCLUSION: These results suggest the involvement of thiol-disulfide homeostasis in the defense against the harmful effects of reactive oxygen species in patients with chronic spontaneous urticaria and the potential role of TDHPs in monitoring H1-antihistamine therapy. To the best of our knowledge, this is the first study investigating TDHPs in patients with chronic spontaneous urticaria before and after treatment.