Adult eczema can be caused by internal factors (infection, endocrine and metabolic changes, neuropsychiatric factors, etc.); it can also be triggered by external factors (food, inhalants, environment, etc.). Internal factors leading to adult eczema mainly include chronic infections, such as chronic cholecystitis, tonsillitis, intestinal parasites, etc.; endocrine and metabolic changes, such as menstrual disorders, pregnancy; and other factors, such as neuropsychiatric factors, genetic factors, etc., which can increase the susceptibility of individuals. External factors leading to adult eczema mainly include daily consumption of food, such as fish, shrimp, beef and lamb in the protein content; inhalants such as pollen, dust mites, etc.; life may come into contact with all kinds of chemicals, such as cosmetics, soap, synthetic fibers, etc.; and other special environment, such as heat, dryness and so on. In conclusion, eczema in adults is a complex process with many factors. Once the symptoms of eczema appear, it is necessary to clarify the triggers in time, avoid re-exposure, and follow the doctor’s instructions for standardized treatment of eczema.