The causes of eczema in children include: allergic reaction. Allergy is actually a state of immune abnormality. There is a special unitary substance protein in a child's body, which will cause a specific anti-antibody reaction in the body. When this anti-antibody reaction is expressed in the body, skin eczema can occur. Therefore, skin eczema often recurs or a large amount of skin eczema occurs after eating something. When the child's eczema heals without treatment after changing his diet, it means that he has an allergic reaction, which is related to allergic reactions caused by diet.