Rhupus Syndrome With Multiple Drug Intolerances Managed by Reduced-dose Rituximab and Adjunctive Molecular Hydrogen Therapy: A Case Report

Background/Aim: Rhupus syndrome, an overlap of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), is a rare condition characterized by heterogeneous clinical manifestations and difficult management. Conventional therapies, including glucocorticoids, disease-modifying anti-rheumatic drugs (DMARDs), immunosuppressants, and biologics, are often limited by drug intolerance and steroid-related complications. Molecular hydrogen (H2) has emerged as a potential adjuvant therapy due to its antioxidant and immunomodulatory properties. This report aimed to evaluate the clinical efficacy of H2 as an adjunct to rituximab in a patient with refractory Rhupus and multiple drug intolerances. Case Report: We report a 47-year-old male with a 27-year history of rheumatoid arthritis, who subsequently developed systemic lupus erythematosus, fulfilling criteria for Rhupus syndrome. His disease course was complicated by multiple drug intolerances, including adverse reactions to methotrexate, sulfasalazine, hydroxychloroquine, azathioprine, leflunomide, and rituximab at standard dosing. Despite reduced-dose rituximab and mycophenolic acid, disease activity persisted and lupus nephritis was confirmed. In October 2023, oral molecular hydrogen capsule therapy was initiated as adjuvant treatment, resulting in significant clinical improvement, which was paralleled by characteristic changes in T- and B-cell subsets, normalization of anti-dsDNA antibody, erythrocyte sedimentation rate (ESR), and complement levels, and successful discontinuation of prednisone. Hydrogen therapy was well tolerated without major adverse effects. The patient developed avascular necrosis from prior corticosteroid use but recovered well after hip arthroplasty in January 2025. Disease control was sustained with mycophenolic acid and continued hydrogen therapy. Conclusion: This case suggests molecular hydrogen therapy as a potential adjuvant for refractory Rhupus with multiple drug intolerances, showing immune modulation, reduced inflammation, steroid withdrawal, and sustained control with low-dose rituximab. Further studies are needed to confirm its efficacy and standardize its use.