PurposeRikkunshito, a traditional Japanese herbal medicine, is used to improve gastrointestinal (GI) function. However, its mechanisms of action in irritable bowel syndrome (IBS) remain unclear. This study aimed to investigate the effects of Rikkunshito on colonic pacemaker activity, inflammation, GI hormones, pain-related behaviors, and transient receptor potential (TRP) channel activity in a zymosan-induced IBS mouse model.MethodsRikkunshito composition was analyzed by UPLC. Pacemaker potentia