Background Colonic dysmotility is a hallmark pathophysiology in many functional and organic bowel disorders. Functional constipation is often one of the symptoms in bowel disorders, that by the presence of abdominal pain or discomfort, is responsible for a low quality of life. STW 5 (Iberogast®) is an herbal medicinal product with a proven clinical efficacy in functional gastrointestinal disorders including functional dyspepsia and irritable bowel syndrome.