Itchy skin after applying mask may be caused by allergy, or it may be caused by long time dehydration of the skin. 1. Allergy: itchy skin after applying masks may be caused by allergies, some masks contain allergenic ingredients or skin itself is sensitive, after applying masks can lead to skin allergic reactions, resulting in itchy skin, redness, etc., at this time, you should stop using the mask, and rinse the face with water, if necessary, can be hospitalized. 2. Skin dehydration: If the skin is in a situation of extreme dehydration, when applying masks can appear itchy skin, there can be a tingling sensation, which is a normal physiological phenomenon, this time there is no need to worry about, generally in a few minutes after the disappearance. If the mask when the skin itchy, in a few minutes can not be relieved, it is recommended to go to the hospital in a timely manner, under the guidance of the doctor to carry out active treatment, do not unauthorized use of drugs to avoid adverse reactions.