Both allergic dermatitis and urticaria are allergic diseases, but they have their differences, including the following: a. In terms of etiology, allergic dermatitis is mainly due to allergic reactions caused by contact with cosmetics, facial cleansers, and inhaled substances such as cat hair and dog hair. In addition to the above-mentioned allergic factors, infections, medical diseases and psychiatric factors can also cause hives. The rash form, allergic dermatitis can appear erythema, papules, papules, blisters and other polymorphic rashes, urticaria can appear in different sizes and shapes of windbags or edematous erythema.