The number of allergic substances is increasing. There are many types of antigens that can cause allergic reactions in humans: 1, diet and drugs Mainly high-protein foods, food additives and drugs. 2, toiletries including a variety of detergents and disinfectants, cosmetics, paints and other products. 3, environmental pollutants mainly refers to chemical particles floating in the air (there are at least 10,000 kinds of allergenic substances that can cause allergic reactions in humans). Skin allergies are medically known as allergic reactions. When the body is stimulated by antigenic substances inside and outside the body, the body produces the corresponding antibodies or sensitizing lymphocytes, which sensitize the body; when the body is exposed to the same antigen again, an antigen-antibody reaction occurs, that is, an immune response. This is a good phenomenon, which is the normal immune defense function of the body, but when the immune response is excessive, hypersensitivity reactions, such as allergic dermatitis, can occur. Don’t treat yourself after an allergy The incidence of allergic skin diseases is increasing because of the many substances that can cause allergies. Most allergies can be cured quickly if the exact allergen can be found, re-exposure is avoided, and glucocorticoids and antihistamines are applied appropriately. However, most allergic dermatitis are difficult to find the exact allergen and are constantly exposed to it in daily life, as a result of which patients are prone to remission when medication is used and aggravation when it is discontinued. This not only makes the patient suffer from the disease and undergo great psychological stress, but also becomes a difficult problem in treatment. It is especially important to remind some young women that when facial allergic dermatitis occurs, they should not go to pharmacies without permission to buy glucocorticoids (such as: dexamethasone acetate cream, also known as dermatoprost) for topical application or to beauty salons for desensitization treatment, otherwise it will easily lead to facial epidermal thinning and capillary dilation and hormone-dependent dermatitis.