Pruritus is a skin disease in which the skin itches spontaneously without primary damage. It is manifested as itchy skin without a primary rash, and the more it is scratched, the more itchy it becomes, with striated scratches, blood scabs, desquamation, keratinization, pigmentation, and secondary dermatitis-like changes over time. The pruritus site can be perianal, vulva, calves and other limited areas, but also can be generalized pruritus. The top ten causes of pruritus: 1, seasonal factors: cold and dry climate, sebaceous glands and sweat glands secretion reduction, skin loss of moist. 2, age factors: the elderly skin atrophy, sebaceous glands atrophy, sebum secretion reduction, skin blood circulation disorders. In the cold season of autumn and winter, the symptoms will be significantly aggravated. 3, chronic kidney disease: especially uremic patients, because the metabolites in the body can not be excreted from the urine, and turn to the skin sweat gland row, stimulating the skin appears dry skin, flaking, itching. 4, diabetic patients: due to reduced insulin secretion, sugar, fat and protein metabolism disorders, so that pyruvate and lactate accumulation in the nerve tissue and induce neuritis, appear skin 5, chronic hepatobiliary disease: can cause bile stasis, bile salts into the subcutaneous stimulation of peripheral nerves, can cause very persistent local or generalized itching. 6, chronic thyroid disease: such as hyperthyroidism due to increased basal metabolism, sweating, tension can cause itching; hypothyroidism can cause subcutaneous mucous edema and cause skin itching. 7, intestinal parasitic disease: can cause generalized or perianal itching. 8, itching is also closely related to certain The reason is not completely clear, probably because the tumor tissue cells will produce histamine and some bioactive substances, stimulating the sensory nerve endings of the skin caused. 9, drinking alcohol or over-eating spicy stimulating food can induce itching. 10, bathing too often, bath, soap stimulation: can cause sebum loss, dry skin, itching. Contact with chemical fibers, wool, off-color clothing can sometimes appear itchy skin. Only to identify the causes of itching can be targeted prevention and treatment.