Dry skin is also known as desiccation of the skin, clinical manifestations mainly include dry skin, roughness, flaking, etc., and some patients may also be accompanied by erythema, cracks, and itching and other uncomfortable symptoms, which are mainly divided into physiological dry skin and pathologic dry skin. 1. Physiological dry skin: mostly seen in preterm infants and the elderly, belonging to the normal physiological phenomenon. (1) Physiological dry skin of preterm infants is mainly manifested in the fact that after birth, the skin is separated from the amniotic fluid environment, the water balance between the skin and the external environment is interrupted, and the skin is extremely sensitive and fragile, which leads to dryness, roughness, flaking and other uncomfortable symptoms; (2) Physiological dry skin of the elderly, mainly manifested as the aging of the skin of the elderly, the epidermal renewal is also slow, so the tissue repair and sebaceous gland secretion function is reduced, thus the phenomenon of dryness. 2. Pathological dry skin: this type of dry skin is often caused by some diseases, such as psoriasis, atopic dermatitis, ichthyosis, etc., the patient will not only have dry, rough, scaly skin and other symptoms, but also accompanied by skin erythema, cracks and itching. When the skin is dry and accompanied by other uncomfortable symptoms, it is important to pay attention to timely visit the hospital, under the guidance of the doctor for standardized treatment.