The pathogenesis of eczema is still unclear, and may be caused by a combination of internal and external factors, internal factors mainly include chronic infectious lesions, endocrine changes, etc., and external factors are mainly environmental factors. 1. Internal factors: including chronic infectious lesions (such as chronic cholecystitis, etc.), endocrine and metabolic changes (such as menstrual disorders, pregnancy, etc.), blood circulation disorders, mental stress, insomnia, over-fatigue, immune function abnormalities, nutritional deficiencies, tumors and so on. 2. External factors: including the surrounding environment stimulation, such as sun exposure, ultraviolet radiation, cold stimulation, excessive dryness, etc., as well as contact with a variety of animal fur, plant pollen, chemical dust, cosmetics, synthetic fibers and other substances, skin stimulation, can induce the formation of eczema. When eczema occurs, patients should consult a doctor in time to identify the cause of the disease under the guidance of the doctor, and follow the doctor’s instructions for appropriate treatment.