The common causes of itchy skin include physiological factors such as dry skin and pathological factors (including cholinergic urticaria, red milia, systemic diseases, etc.). 1. Physiological factors: generally in the dry environment, resulting in the human skin is too dry, skin barrier damage, skin prickling sensation can occur; in addition, if the emotion is too excited, exercise, etc., can lead to the human body blood temperature, sweat secretion exuberant, there can be prickling sensation. 2.Pathologic factors (1) cholinergic urticaria: this disease is mainly caused by exercise, heat, emotional stress, after eating hot drinks, the deep body temperature rises, so that the cholinergic nerve impulse and release acetylcholine, the role of mast cells and the onset of the disease, manifested in the appearance of the skin 1 ~ 3mm round papular eruptions, surrounded by a varying degree of redness, self-awareness of itchy, itchy, burning sensation and other symptoms. (2) red corn rash: this disease is in the hot and stuffy environment, a large amount of sweat is not easy to evaporate, so that the stratum corneum impregnated with swelling, sweat ducts become narrowed and blocked, sweat stagnation in the sweat ducts, the pressure rises, the sweat ducts rupture, sweat infiltration of the surrounding tissues and the onset of the disease, the patient often has a tingling sensation, lesions manifested as a pinpoint-sized papule, papule herpes, surrounded by red halos, and other symptoms. (3) systemic diseases: such as diabetes mellitus, due to the body’s elevated blood glucose concentration, resulting in microcirculation disorders and nerve demyelination lesions, causing peripheral neuropathy, can appear as a generalized pinprick itching symptoms. If you suspect that the disease is caused by the patient is recommended to go to the regular hospital dermatology consultation, follow the doctor’s instructions to clarify the diagnosis and timely treatment.