Psoriasis vulgaris is a common, chronic inflammatory skin disease with a prevalence of 1.5-2% in Western industrialized countries. A relevant percentage of patients suffer from moderate-to-severe psoriasis and experience a significant reduction in quality of life. The choice of an adequate therapy could help to prevent disease and exacerbation of comorbidity, which could increase quality of life, avoid hospitalization and avoid reduction of working days. The present guidelines are focused on the initiation and management of systemic therapies in cases of moderate-to-severe plaque-type psoriasis in adults to optimize treatment response, adherence and quality of life. This first version of the Swiss S1 guidelines presents therapeutic recommendations which are based on a systematic literature search as well as an informal expert consensus of dermatologists in Switzerland.