Pruritus is usually thought to be caused by skin disorders. The most common cause is geriatric winter pruritus, which is caused by atrophy of sebaceous and sweat glands due to endocrine decompensation, resulting in excessive dryness of the skin and aging metamorphosis of the nerve endings receptors distributed in the wrinkled skin, which sends an unusual stimulus signal to the center, causing itchy skin, especially in severe winter. There are also some particularly obvious, persistent or recurrent itching of the skin, without any primary rash, is mostly a signal of certain diseases, should be promptly to the hospital, early treatment, so as not to become a serious disease. Digestive system diseases: the first see hepatobiliary diseases, including obstructive jaundice jaundice, hemolytic jaundice, etc., because of the increased concentration of bile salts in the serum and skin, stimulating the nerve endings and cause generalized itching of the skin. Endocrine system diseases: about 10% of patients with “hyperthyroidism” and “hypothyroidism” have pruritus, but there is a difference between the two. The itching of “hyperthyroidism” appears earlier, because the skin of “hyperthyroidism” is more humid, so it is mostly aggravated in summer; while the itching of “hypothyroidism” appears later and develops slowly, and the skin is drier and rougher, so it is more likely to induce itching in winter. Diabetic patients because of elevated blood sugar, the body’s immunity and resistance to disease significantly reduced, more susceptible to bacterial, viral infections and induced itchy skin. Pregnant women due to endocrine disorders during pregnancy can lead to “pregnancy itch”, due to the rise in estrogen and progesterone during pregnancy, will automatically disappear after delivery. Genitourinary system diseases: Patients with chronic nephritis, especially in the late stage (uremic phase), are unable to excrete metabolic wastes such as urotoxins and urea from the blood, and retain a large amount of them in the body and excrete them with sweat, thus causing generalized intractable itching, which is unbearable. In middle-aged and elderly women, vulvar itching often occurs due to irregular menstruation, increased leucorrhea, unclean vulva, ovarian lesions, or vulvar inflammation due to vaginal trichomonas and fungal infections. Hematologic disorders: True erythrocytosis is mostly associated with generalized pruritus, some manifesting as burning and stinging pain, aggravated in summer, worse after a hot bath, relieved after half an hour, and aspirin can slow down such itching. About 15-20% of patients with iron deficiency anemia have generalized or localized pruritus, which can be relieved after iron supplementation and correction of anemia. Central nervous system diseases: neurasthenia, cerebral arteriosclerosis, cerebral edema and brain tumors can lower the itch threshold of central receptors, leading to itchy skin. Miraculously, brain tumors that infiltrate the base of the fourth ventricle cause intense and persistent itching of the skin near the nostrils of the face, which then progresses to the entire face and neck. Malignant tumors: Most tumors can cause generalized itching of the skin due to irritation of nerve endings by cancer cells and metabolites. Stomach and liver cancers often have mild itching all over the body in the early stage, and the itching increases as the cancer progresses. Lymphatic system cancers such as mycosis fungoides and Hodgkin’s disease are associated with generalized pruritus. Rectal and colon cancers often manifest as anal itching; various leukemias, lung and esophageal cancers are associated with generalized pruritus. Other pharmacogenic pruritus: Mostly seen in old patients who are frail and sickly, cross-use of multiple drugs, many oral and injectable about substances can cause pruritus in those with skin allergies, and it is more likely to occur when drugs are combined. Infectious itch: rural mountainous areas and other areas with poor sanitary conditions often have scabies mite infection causing itch, confined to the fingers, toes and ankles, severe cases throughout the body, more difficult to cure. 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 all the above-mentioned diseases should be considered. You should go to a major hospital as soon as possible to find out the root cause of the disease and treat it symptomatically to eliminate future problems.