There are some painful itchy skin, such as particularly obvious persistent or recurrent itching, but without any prior or concurrent rash, is mostly a signal of a variety of diseases, should be promptly to the hospital, early treatment, so as not to become a major disease. First, digestive system diseases Common hepatobiliary diseases, including obstructive jaundice, hemolytic jaundice, etc., due to increased concentrations of bile salts in the serum and skin, stimulating the nerve endings and causing generalized itching of the skin. Pregnant women due to endocrine disorders during pregnancy can lead to “pregnancy itch” because of the rise in estrogen and progesterone during pregnancy, which will automatically disappear after delivery. Endocrine system diseases “hyperthyroidism” and “hypothyroidism” occur in about 19% of patients with pruritus, but there is a difference between the two, “hyperthyroidism The itching in “hyperthyroidism” appears earlier and is mostly aggravated in summer because the skin of “hyperthyroidism” is more humid, while the itching in “hypothyroidism” appears later and develops slowly, with drier and rougher skin, which is more likely to Itching is more likely to be induced in winter. Diabetic patients because of elevated blood sugar, so that the body’s immunity and resistance to disease significantly decreased, more susceptible to bacterial, viral infections and induced itchy skin. Third, the blood system diseases true erythrocytosis is mostly accompanied by generalized itchy skin, some manifestations of burning and stinging, aggravated in summer, more so after a hot bath, half an hour later to relieve, the wonderful aspirin can slow down such itching. Iron deficiency anemia 15%-20% of patients with generalized or localized itching, after iron supplementation and correction of anemia, the itching can be relieved. IV. Central nervous system diseases Diseases such as neurasthenia, cerebral arteriosclerosis, cerebral edema and brain tumors can lower the itch threshold of central receptors and lead to itchy skin. In addition, when brain tumor infiltrates to the bottom of the fourth ventricle, it will cause intense and persistent itching of the skin near the nostrils of the face, and then develop to the whole cheek. V. Malignant tumors Most tumors can cause generalized itchy skin due to stimulation of nerve endings by cancer cells and metabolites. Gastric cancer and liver cancer usually have mild itching in the early stage, but itchiness will increase as the cancer progresses. Lymphatic system cancers such as mycosis fungoides and Hodgkin’s disease are associated with generalized pruritus. Rectal and colorectal cancers often manifest as anal itching; various leukemia lung cancers and esophageal cancers are accompanied by generalized pruritus. Six, other causes of pruritus 1, pharmacogenic pruritus: mostly seen in frail, multi-drug cross-use of older patients, many oral and injectable drugs can cause pruritus in people with skin allergies, and more likely to occur when combined with drugs. 2, infectious itch: rural mountainous areas and other areas with poor sanitary conditions, often caused by scabies mite infection and itch, mostly confined to the fingers, toes and ankles, severe cases throughout the body, more difficult to cure. 3, drug addiction itch: drug addiction are suffering from “delusional skin parasitosis”, that is, hallucinations of the feeling of worms crawling under the skin, manifested as itchy skin uncomfortable, which is the skin of drug addiction hallucinations. Therefore, where suffering from persistent, recurrent and persistent pruritus, and can not be satisfactorily explained by dermatological disease, the possibility of the above-mentioned diseases should be considered. It is important to go to the hospital as early as possible to find out the cause of the disease and treat it symptomatically in order to eliminate future problems.