Pruritus is a skin disease with only pruritus without primary skin lesions. The etiology of the disease is complex. A variety of internal and external factors can cause generalized pruritus. Internal factors include individual skin traits (e.g., aging, hydration, etc.), neuropsychiatric factors (e.g., various neurological dysfunctions or organic lesions as well as emotional stress, trauma, anxiety, fear, agitation, and depression), systemic diseases (e.g., liver and kidney diseases, hematologic diseases, endocrine and metabolic diseases, malignant tumors, infectious diseases such as parasites, and certain chronic lesions), pregnancy, medications or food Allergies, etc. External factors include environmental factors (such as season, temperature, humidity, light, work and living environment, etc.), lifestyle habits (such as soap, clean skin care cosmetics, wearing clothes, etc.). Certain primary skin diseases can still cause limited pruritus, such as pruritus of the female genitalia and pruritus of the scrotum caused by infection (fungus, trichomonas, pubic lice, etc.), clothing stimulation, drug stimulation, etc., and pruritus of the perianal area caused by hemorrhoids, anal fissure, pinworm infection, etc. Clinical manifestations Generally no primary skin lesions appear and pruritus is the characteristic manifestation of the disease. Generalized pruritus, non-localized, often paroxysmal and aggravated at night; limited pruritus manifests as localized paroxysmal severe itching, mostly in the female pubic, scrotum, perianal, calf and scalp areas. Mood swings, temperature changes, clothing friction, and other stimuli can cause pruritus to flare up or worsen. Itching can cause secondary lesions, including striated scratches, epidermal erosions, blood crusts, hyperpigmentation or hypopigmentation, eczema-like or moss-like changes over time, and various skin infections such as folliculitis, boils, and lymphadenitis. In addition, it can also manifest as burning and insect crawling sensations. Special types of generalized pruritus include: (1) senile pruritus (2) seasonal pruritus (3) water pruritus Diagnosis is made based on the medical history and clinical manifestations, and possible causes are actively sought. In addition to detailed history and physical examination, it is necessary to perform chest X-ray, blood, urine, stool routine, liver and kidney function, blood sugar and patch test. The presence of systemic diseases needs to be clarified and treated promptly. Avoid local irritation, including scratching, washing and scalding and improper treatment, and avoid eating irritating foods.