Expired face masks are usually not recommended for your face anymore. Masks contain many nutrients or moisturizing chemicals. After the expiration date, these nutrients or chemical components may break down into other substances, and other unstable substances may cause irritation and damage to the face or lead to allergic reactions. The stability of any chemical composition and nutrients has a certain period of time, in the shelf life, its nutrients and chemical composition will not change too much, after a long time, these ingredients will be oxidized or decomposed into other substances. Therefore, the expiration date of the mask is not recommended to be used for face again, if the face of discomfort, it is recommended to timely hospital dermatology consultation.