Allergic swelling on the face may be caused by eczema, urticaria, contact dermatitis and other diseases. 1. Eczema: it is a chronic inflammatory itchy skin disease, the cause of which is mainly related to genetics, immune abnormalities and other factors. Eczema may be induced by improper diet or contact with allergens such as pollen and animal dander, which may cause red spots, pimples and even swelling on the face. 2. Urticaria: It is a kind of edematous mass confined to the skin and mucous membranes, the cause of which is mainly related to food allergies, infections, autoimmunity and other factors. The patient mainly manifested as a wind, may be accompanied by angioedema, will lead to localized swelling. 3. Contact dermatitis: an inflammatory skin disease triggered by skin contact with external substances. If the patient’s face comes into contact with hair dyes, cosmetics and other allergy-sensitive substances, it may lead to redness and swelling on the face. There are many reasons for the allergic swelling of the face, it is recommended that patients go to the hospital to clarify the cause of the disease, and follow the doctor’s instructions for treatment.