I. Concept: refers to clinical symptoms of pruritus only without primary skin damage of the skin disease. Second, the etiology: a variety of complex, visceral disorders; local disorders; physical and chemical factors; biological factors Third, clinical manifestations: according to the location and extent of itching, generally can be divided into two categories: generalized and restricted. 1, systemic pruritus: pruritus is paroxysmal, often occurs before bedtime, emotional changes, eating spicy food and after climate change. In severe cases, itching is often unbearable, affecting sleep and work. The skin often develops secondary scratches, blood crusts, mossy lesions, eczema-like lesions, pigmentation, and secondary infections. (1) elderly pruritus: mostly due to sebaceous gland function, resulting in dry skin, prone to generalized generalized pruritus. (2) Winter pruritus: Most often occurs in winter when patients undress before bedtime, and occurs on the femur, posterior calf, anterior shin and hip. The skin is often dry, flaky and mossy. 2, limited pruritus: pruritus occurs in a certain part of the body, called limited pruritus. (1) anal pruritus: pruritus is limited to the anus and surrounding skin, the lesions are grayish-white, macerated, erosion, crepitus, radial chaps, mossy lesions and pigmentation. (2) Scrotal pruritus: limited to the scrotum, may also involve the perineum, paroxysmal episodes, lesions are hypertrophic, eczema-like changes, mossy changes and hyperpigmentation. (3) Pruritus of the female genitalia Most commonly seen in the labia majora and minora, the clitoris and the vaginal opening. Pruritus is paroxysmal, aggravated at night, with local skin hypertrophy and maceration, and the clitoris and clitoral mucosa even appear edema and erosion, often causing depression and other symptoms in patients. (4) Pruritus of the head, pruritus of the lower legs, pruritus of the palmoplantar and pruritus of the external ear canal are also common restricted pruritus. Clinical management principles: Active search for the primary cause and corresponding treatment is the key to prevent this disease. Pay attention to the regularity of life, less alcohol, tobacco and spicy food, quit scratching habits, avoid external stimulation, bathing without alkaline soap and hot water washing.