Psoriasis is a common dermatological disorder characterized by an immune-mediated chronic inflammation which is associated with a variety of other diseases commonly referred to as comorbidities. The treatments for these diseases may interfere with the course and the treatment of psoriasis. Little is known on the general drug intake of patients with psoriasis. To gain more insight into the general drug intake of patients with severe psoriasis. A correlation of comedication to respective diseases could lead to a better knowledge of comorbidities. Data on demographics, comedication and comorbidities from 1203 patients with severe psoriasis in Germany were analysed. As a control group data from 7099 subjects from the German National Health Survey 1998 were used. Patients with severe psoriasis are receiving significantly more different systemic drugs on average than the general population, with the most prominent difference in multidrug treatment. Drugs used in the treatment of arterial hypertension, diabetes mellitus and other diseases of the metabolic syndrome as well as oral anticoagulants and anticonvulsant agents showed the greatest differences. Special characteristics of antihypertensive drug treatments could be determined. The data obtained in this study provide the basis for an improved management of patients with psoriasis. Knowledge of existing comedication and comorbidities may lead to the ability to treat psoriasis and comorbidities at the same time more safely and to use possible synergistic effects.