Sudden allergy, redness, swelling and itching of the face firstly need to avoid contact with allergens, and secondly through physical therapy and medication to improve the disease. 1. Avoid contact with allergens: some people may be allergic to dust, seafood and other foods, and the use of skin care products that are not suitable for their skin type can also lead to allergic reactions on the face, resulting in redness, swelling and itching. Patients should minimize re-exposure to allergens to avoid aggravation of the disease. 2. Physical therapy: patients can use saline to apply cold compresses to the red, swollen and itchy parts of the face to help relieve the discomfort. 3. medication: you can use anti-allergy drugs under the guidance of the doctor for treatment, such as loratadine. Can also be used with the use of topical glucocorticoid cream, such as hydrocortisone butyrate cream. It is recommended that patients with allergic reactions to the face, redness, swelling and itching symptoms, should immediately go to the hospital to seek medical treatment, a doctor for the specific symptoms of symptomatic treatment, so as not to delay the condition.