Recently, several herbal formulas and probiotics have been simultaneously administered to IBS patients for relieving abdominal symptoms19. In addition to lack of clinical evidence for the use of GJS or DUO, the efficacy of their combined treatment for IBS has not been elucidated. Thus, there is a need to evaluate the safety and efficacy of administration of GJS, DUO, or a combination therapy as a frequently used treatment for IBS. In the current trial, we identified the safety and efficacy of GJS, DUO, or a combination therapy on D-IBS by evaluating IBS symptoms and quality of life. To investigate their mechanisms in humans, intestinal permeability and composition of intestinal microbiota were assessed.