Allergic dermatitis is a type of skin disease caused by allergies, including eczema, urticaria, contact dermatitis, and so on. Due to the different types of diseases, there are some differences in the symptoms and manifestations. Generally manifested as different types of rashes, accompanied by itching, redness and swelling and other symptoms. 1. Eczema: the skin is mainly characterized by pimples, erythema, cracks and other symptoms, accompanied by more obvious itching. 2. Urticaria: mainly giant flaky rash, the skin is usually bright red or light red, accompanied by different degrees of itching. 3. Contact dermatitis: mainly with blisters, edema, erythema and other symptoms. Generally, after removing the allergic substances, the symptoms will gradually subside. It is recommended that patients go to the hospital in time to check the diagnosis, early treatment, early improvement.