Enhancing Social Skills in Schizophrenia Spectrum Disorders - Oxytocin as add-on to Psychosocial Treatment

Inclusion Criteria: 1. Age 18 to 64 years 2. Written informed consent (must be available before enrolment in the clinical trial) 3. ICD-11 diagnosis of schizophrenia or other primary psychotic disorders (6A20-6A25) confirmed by the MINI-DIPS-OA Interview 4. At least one symptom of moderate severity or worse in the PANSS negative subscale (a score ≥ 4 for one or more symptoms from N1-N7 at baseline). 5. In- or outpatient psychosocial treatment on a regular basis at least twice a week during the study 6. Male participants and female participants who are not capable of bearing children or female patients of childbearing potential who use a highly effective birth control method that is medically approved by the health authority at screening. 1\. Age 18 to 64 years 2. Written informed consent (must be available before enrolment in the clinical trial) 3. ICD-11 diagnosis of schizophrenia or other primary psychotic disorders (6A20-6A25) confirmed by the MINI-DIPS-OA Interview 4. At least one symptom of moderate severity or worse in the PANSS negative subscale (a score ≥ 4 for one or more symptoms from N1-N7 at baseline). 5. In- or outpatient psychosocial treatment on a regular basis at least twice a week during the study 6. Male participants and female participants who are not capable of bearing children or female patients of childbearing potential who use a highly effective birth control method that is medically approved by the health authority at screening. Exclusion Criteria: 1. Patients who are not suitable for the study in the opinion of the investigator (including acutely suicidal patients) 2. Coercive treatment at the time of study inclusion 3. Diagnosis of primary substance dependency other than nicotine: exclusion alcohol dependency via AUDIT-screening (Bohn, Babor et al. 1995; Babor et al. 2001) and ICD- 11 criteria (MINI-DIPS-OA); exclusion of other drug dependencies other than alcohol and nicotine: drug screening of urine and ICD-11 criteria (MINI-interview: patient fulfilling early (\> 3 months) or sustained (\>12 months) remission criteria and/or with low severity of substance use disorder according to MINI (ICD-11) are eligible for the study). 4. Documented intolerance to the study drug or any of its ingredients. 5. Pregnancy (incl. positive urine or blood pregnancy test) / breastfeeding (female patients) or lactating individuals 6. Severe endocrinological disorder besides diabetes 7. Endometriosis 8. Concurrent participation