Seborrheic dermatitis, also known as seborrheic eczema, is a chronic papulosquamous inflammatory skin disease that occurs in areas rich in sebaceous glands. The disease is most common in adults and newborns and occurs in areas rich in sebaceous glands such as the head, face and trunk. The cause of this disease is not fully understood. The development of seborrheic dermatitis may be related to seborrhea, microorganisms, neurotransmitter abnormalities, physical and climatic factors, nutritional deficiencies, and the action of drugs. In recent years, the relationship between oval spores of furfur and seborrheic dermatitis has gained attention and is believed to play an important role in the pathogenesis of seborrheic dermatitis. In addition, psychological factors, dietary habits, B-vitamin deficiency and alcoholism may also have an influence on the development of the disease. Generalized and persistent seborrheic dermatitis can be an important skin symptom of HIV infection. Symptom performance 1. Occurrence site site: it occurs in fatty, sweaty, hairy areas, such as the head and face, ears, neck, trunk. The forehead, arch of the eyebrows, nasolabial folds, and beard are the main parts of the face; the middle of the chest and back, as well as the axillae, groin, umbilicus and other folds are the main parts of the trunk. The lesions often start from the scalp and spread downward, and in severe cases, they spread all over the body. 2, skin lesion performance: there are dry and wet. The dry ones are light red or slightly red patches covered with white furfuraceous scales. Wet is yellow-red patches, covered with yellowish greasy scabs, serious cases have vesicles, oozing, crust dirty thick with odor. The head damage early oil, or dandruff, itching, followed by thin and soft hair, shedding, baldness. 3.Self-perceived symptoms: itching of different degrees. 4.Course of disease: the course of the disease is chronic, often with acute attacks. 5.Population: Infantile seborrheic dermatitis often occurs in the first month after delivery, the lesions are mostly on the scalp, forehead, between the eyebrows and cheeks, as exudative red patches with yellow greasy scabs.