Facial skin allergic reactions caused by topical masks can normally heal on their own in 5-7 days. Facial allergic reactions caused by facial masks actually belong to type IV hypersensitivity reaction, which is clinically called allergic contact dermatitis. The mask, as a sensitizing factor, is a semi-antigen that is not irritating or toxic in itself but forms a complete antigenic complex after contact with the skin epidermis, thus sensitizing the T cells and producing memory T cells and effector T cells, and upon re-exposure to the allergen, symptoms of allergy will occur, manifesting as localized edematous erythema and itching. When the facial skin is free from the allergen, that is, the mask, the symptoms of facial allergy are gradually reduced until they disappear completely, a process that usually takes about 5-7 days. For some severe contact dermatitis caused by topical masks, clinical advice is still necessary for symptomatic treatment, the routine can use antihistamines, serious cases can be systemic use of glucocorticoids.