The observational study aims to investigate the extent to which a two-week stay in an internal medicine clinic for integrative medicine and naturopathy results in an improvement of complaints, impairments, quality of life, anxiety/depressiveness, stress perception and well-being in chronic gastroenterological patients and chronic rheumatological/pain patients. In addition, previous experiences with complementary naturopathic procedures, expectations of treatment, perceived benefits and implementation of instructed techniques and procedures in everyday life will be investigated. Since May 2021, patients with Post Covid-19 Syndrome have been treated as inpatients during a stay that usually lasts 14 days. Since January 2022 these patients are evaluated in the substudy StaPoCo. Since 2022 Post Covid-19 Syndrome day clinic patients were also evaluated. Sub-Study Intestinal barrier dysfunction - Gastroenterological patients who undergo routine gastroscopy and/or colonoscopy with confocal laser endomicroscopy (cLE) and tissue biopsies at the beginning of their inpatient stay are explicitly examined for the presence of a barrier disorder. Since May 2021 patients can take part in the day clinic programme one day weekly for ten or eleven weeks. In this programme also patients with oncological disorders take part. Starting in the fall of 2022, the integrative medicine/naturopathic day clinics at the Immanuel Hospital in Berlin and the Ev. Kliniken Essen-Mitte will be included in the evaluation.