Usually there will be red patches on the contacted area, some will have blisters, more serious will have blisters, broken trauma vesicles, fluid exudation, patients often feel itchy. This disease has a clear history of contact, the removal of the cause of the disease can be self-healing; 2, atopic dermatitis: also known as atopic dermatitis, is a chronic, recurrent skin disease. Patients or their families often have a history of urticaria, asthma, allergic rhinitis and other diseases. Treatment is mainly to restore the skin barrier and remove the triggering factors. Treatment needs to be carried out in a professional hospital, during treatment pay attention to a light, non-stimulating diet, clothing to soft, comfortable; 3, urticaria: the cause of urticaria is more complex, with genetic factors, endocrine factors, infection and other factors. Usually manifested as a wind cluster on the skin, often accompanied by itchy skin. Most patients can heal themselves after a few hours; 4. Eczema: This is an allergic disease. Its triggering factors often vary depending on the individual and the stage of the disease, so it is not easy to determine. Clinically, itching is often significant and symmetrically distributed, with acute papules predominating with a tendency to exude, and chronic often with moss-like changes and recurrent episodes.