Clinical Effectiveness of Rikkunshito in Neonates With Radiologically Confirmed Gastroesophageal Reflux Disease and Gastric Volvulus

Aim This study aimed to evaluate the efficacy and safety of rikkunshito for neonatal gastric dysmotility associated with radiologically confirmed gastroesophageal reflux disease (GERD) and/or gastric volvulus (GV) and to explore factors related to treatment response. Methods We conducted a single‐center retrospective observational study in the neonatal intensive care unit of a regional perinatal center from January 2016 to December 2024. We included neonates and infants younger than 2 months at diagnosis who had GERD and/or GV confirmed by contrast upper gastrointestinal radiography and received rikkunshito for persistent vomiting or feeding intolerance. Primary outcomes were changes in daily weight gain, milk intake, and vomiting frequency over the 7 days before and after initiation. Secondary outcomes were correlation analyses with various clinical parameters. Results Nineteen infants met the inclusion criteria. Mean of daily weight gain, milk intake, and vomiting frequency improved significantly ( p < 0.01). Infants whose symptoms began within the first 7 days of life showed greater improvements in weight gain and vomiting than those with later onset. Earlier age at rikkunshito initiation correlated with larger gains in weight, and increases in milk intake correlated with improvements in weight gain. No serious adverse events were observed. Conclusions Rikkunshito administration was associated with marked improvements in weight gain, feeding tolerance, and vomiting in neonates with GERD and/or GV, without observed serious toxicity. Earlier initiation may enhance treatment response. Prospective controlled studies are warranted to confirm these findings and to define optimal dosing strategies in this population. Trial Registration: T2024‐0049.