The tongue is rotten, that is, the tongue mucosa appears erosion, may be flat moss, herpes simplex, pemphigus and other diseases, specific as follows. 1. lichen planus: its etiology and pathogenesis are not clear, may be related to immune factors, psychiatric factors, endocrine factors, etc. Lichen planus vesiculobullous manifestation of irregular vesiculobullous surface covered with yellowish pseudomembrane, and the edge of the congested red, can be accompanied by congestive erythema, white reticulation lesions. 2. Herpes simplex: caused by herpes simplex virus infection, herpes simplex virus can form clusters of small blisters on the tongue, the blisters can form irregular vesicles after bursting, and if there is secondary infection, ulcers can be formed. 3. Pemphigus: it is an autoimmune disease, may be related to genetic and environmental factors, the tongue can appear blisters, after the ulceration of irregular vesicles, the edge is clear, the surface is clean and the pseudomembrane is less. There may be other reasons for the tongue to rot, it is recommended to go to the hospital in time, clear causes for targeted treatment.