In total, 41 patients with psoriasis were assigned to receive hydrogen water bath therapy and 34 patients were assigned to a control group. Treatment groups were well balanced with respect to demographics and baseline characteristics (Table 1). During the course of the study at Week 2, only one control patient withdrew due to lack of improvement and she was counted as a non-responder in the control group. After 8 weeks of bath treatment, the reaction was evident. The mean Psoriasis Area Severity Index (PASI) score and median Visual Analogue Score (VAS) score in the hydrogen water bath group at week 8 were 5.8 and 0, respectively, which were significantly lower than the baseline scores (P =7.08 × 10-6; P  = 2.42 × 10 -5 ).

After 8 weeks of treatment, patients who received the hydrogen water bath showed significantly greater improvement than those in the control group, as assessed by PASI and VAS (Table 2 and Fig. 1). Among the patients who received the hydrogen water bath, 24.4% had at least a 75% improvement in their PASI score compared to 2.9% in the control group (Pc = 0.022, OR = 0.094, 95% CI = [0.011, 0.777)]). Among the patients who received the bath, 56.1% had at least a 50% improvement in PASI compared to only 17.7% in the control group (P = 0.001, OR = 0.168, 95% CI = [0.057, 0.492]). Hydrogen water bath treatment also significantly improved itching as measured by VAS. The median change from baseline to week 8 in the bathing group was -2, while the median change in the control group was 0 ( P   = 3.94 × 10 -4 ).

Clinical improvement in psoriasis treated with 8-week hydrogen water bath therapy. Case 1: A 64-year-old patient with psoriasis at baseline (PASI 16.4, a, b) and after bath therapy (PASI 1.8, c, d). Although he took 30 mg of acitretin capsules daily for more than 4 months, the psoriatic lesions did not improve, only the scaly parts of the plaques decreased. Due to unbearable dryness and chapped mucous membranes, he refused to increase the dose of the drug. Case 2: A 40-year-old patient with psoriasis at baseline (PASI 21.1, a, b) and after last bath treatment (PASI 4.1, c, d). He complained of severe itching and refractory lesions (Acitretin Capsules 40 mg per day for 6+ months) and after the bath treatment he was able to reduce the dose. Case 3: A 43-year-old patient with psoriasis at baseline (PASI 20.2, a, b) and after last bath therapy (PASI 4.8, c, d). The man was treated with 5 mg of methotrexate weekly for more than 10 months and was able to successfully reduce the dose after the bath treatment. Note that patients experienced similar responses in areas not shown.