In the planned efficacy study, a prospective randomized controlled trial will be conducted to investigate the extent to which a multimodal stress reduction and lifestyle modification program can be reflected in patients with irritable bowel syndrome (IBS) within the framework of a clinical study. For this purpose, 118 patients with IBS will be enrolled in a clinical study. The intervention group will participate in a partial outpatient multimodal stress reduction and lifestyle modification program over 10 weeks, while the waitlist control group will only receive an educational session and written information on treatment and self-help options. The primary research question encompasses the examination of the program's impact on the severity of symptoms associated with irritable bowel syndrome (measured with the IBS-Symptom Severity Scale \[IBS-SSS\]) and additionally its influence on quality of life, stress, and mental well-being. Another aspect of the study is the utilization of medical services (e.g., comparing the number of doctor visits; intake of prescribed and over-the-counter medications). Additionally, a comparison of days of work disability will be conducted.