[Rational diagnostics in pruritus].

Pruritus (itch) is the most frequent skin symptom. It can be attributed to a skin disease in many cases. Furthermore pruritus may also be a precursing symptom or principal complaint of an internal, neurological or psychiatric disease. It has been observed that elderly patients are increasingly affected. In many cases pruritus has multifactorial causes. This requires careful diagnostics, including a detailed medical history and medical examination of the patient. Previous diseases and comorbidities need to be considered as possible causes, as well as current and previous drug intake. By this important information can be obtained at an early time, which may lead to further investigation. Aim of rational diagnostics is to evaluate especially internal diseases which need to be assessed by laboratory testing and more specific diagnostics. Due to the multitude of possible causing diseases, diagnosis and therapy of chronic itch need an interdisciplinary approach.