Chinese herbal formula Tongxie Yaofang for diarrhea-predominant irritable bowel syndrome: study protocol for a randomized, multiple-blind, placebo-controlled trial.

Introduction: Diarrhea-predominant irritable bowel syndrome (IBS-D) is a bowel disease with a high incidence. It significantly reduces the quality of life of patients and affects the patient's daily activities and mental health. No specific therapeutic medications for IBS-D have been found.