Clinical Effects of Adjunctive Shoseiryuto Therapy in Refractory Eosinophilic Chronic Rhinosinusitis: A Pilot Retrospective Case Series Focusing on Mucus‐Related Symptoms

ABSTRACT Aim To evaluate the efficacy and safety of adjunctive shoseiryuto, a traditional Japanese Kampo medicine, in patients with refractory eosinophilic chronic rhinosinusitis (ECRS), with particular attention to mucus‐related symptoms. Methods This retrospective pilot case series was conducted at Osaka Medical and Pharmaceutical University Hospital and included patients with recurrent histologically confirmed ECRS who received adjunctive shoseiryuto between April 2022 and April 2024. Shoseiryuto (TJ‐19, 9 g/day) was administered for approximately 2 months in addition to ongoing standard medical therapy. Treatment outcomes were evaluated using VAS scores, SNOT‐22, nasal endoscopic findings, and safety assessments. Results Six patients met the eligibility criteria and were included in the analysis. VAS scores showed significant improvement in postnasal drip ( p = 0.03), while nasal obstruction and runny nose showed trends toward improvement ( p = 0.06 each). In the SNOT‐22 analysis, “thick nasal discharge” significantly improved ( p = 0.03), and the Nasal domain showed a trend toward improvement ( p = 0.06). Endoscopic evaluation demonstrated improvement in viscous nasal discharge in all six patients (100%), while nasal polyp size improved in one patient (16.7%). No patient developed hypokalemia or liver function abnormalities, and no clinically documented adverse events requiring discontinuation of shoseiryuto were identified during the observation period. Conclusion Adjunctive shoseiryuto may improve mucus‐related symptoms in some patients with refractory ECRS. Given the small sample size and retrospective single‐center design, these findings are exploratory and hypothesis‐generating.