Often fall off a layer of white mucous membrane in the mouth may be physiological factors, may also be oral candidiasis, oral leukoplakia, oral ulcers and other pathological factors. 1. There are many reasons why the mucous membrane falls off in the mouth, if there are no other uncomfortable symptoms, it may be a normal phenomenon of oral metabolism, or it may be caused by physiological factors such as drinking less water and eating irritating foods. 2. If the combination of dry mouth, burning sensation of the oral mucosa, pain and other symptoms, white mucous membrane can be seen after wiping away the congested basal mucosa, it is most often considered as oral candidiasis. 3. If the white mucous membrane is rough and woody, and the surface of the lesion is rough and uneven like crumpled paper, oral leukoplakia is mostly considered. 4. If the shedding of white mucous membrane is more limited, visible ulcerated surface, accompanied by pain, it is mostly considered as oral ulcers. The above are some of the possible causes, it is recommended to consult a doctor in time for diagnosis by a professional doctor.