The causes of eczema are relatively complex, often resulting from the interaction of internal and external factors. Internal causes mainly include certain gastrointestinal diseases, insomnia, fatigue, emotional stress, and also include infections, metabolic disorders, and endocrine imbalances. External causes, for example, include food, living environment, and climate changes, all of which can lead to eczema. Additionally, external stimuli such as cold, heat, hot water scalding, cosmetics, and synthetic fibers can also trigger eczema.