Allergic rash is not a single disease, which includes eczema, hives, and drug rash. Since eczema and allergic rashes are in an encompassing relationship, they cannot be completely differentiated from each other. Allergic rash is a generalized term that covers a wide range of diseases, and different types of diseases will present different clinical manifestations in different people. For allergy-induced skin diseases, they can be roughly categorized as allergic rashes, but according to the differences in the causes and clinical manifestations of the disease, a clear diagnosis can be made. Eczema is a skin disease caused by a variety of internal and external factors, easy to recur and accompanied by intense itching is the main feature of eczema, blisters, oozing can occur in the acute stage, and the chronic stage will appear hypertrophy, mossy, scaly and so on. In order to better distinguish the type of allergic rash, it is necessary to consult a doctor and analyze the case based on medical history.