There are many reasons for itchy skin, which is usually caused by skin diseases, mental psychology, systemic diseases and other factors. 1. Skin diseases: mainly including psoriasis, eczema, scabies, urticaria, etc., which will produce different degrees of itching. 2. Mental psychology: when the patient has adverse emotions such as anxiety, tension, depression, or lack of sleep, itchy skin symptoms may occur. As well as parasite paranoia, patients may think they are infected with parasites and feel itchy skin. 3. Systemic diseases: such as diabetes, uremia, liver disease and other systemic diseases, there will be different degrees of itchy skin. Because of the more causes of itchy skin, so when the patient appears to be uncomfortable, should promptly seek medical treatment for formal, systematic examination to confirm the cause of the disease and then targeted treatment.