Wrinkles on the inside of the mouth may be caused by physiological factors such as low water intake and a dry environment, or they may be caused by diseases such as mouth ulcers and sebaceous gland ectasia. 1. Physiological factors: If you drink too little water and the environment is dry, it may lead to dryness of the mouth and wrinkles on the inside of the mouth. If not accompanied by other uncomfortable symptoms, are normal phenomena, do not need to worry too much. 2. Mouth ulcers: the cause of mouth ulcers is not yet clear, may be genetic, low immunity, mental stress, improper diet, trauma and other factors. Patients may have round or oval ulcer surfaces on the oral mucosa, and as the disease develops, the ulcers become large and deep, manifesting as wrinkles on the inside of the mouth. 3. Sebaceous gland ectasia: Sebaceous gland ectasia may be caused by hormone levels, local irritation, smoking and other factors. The clinical symptoms of patients with skin, mucous membrane damage, can appear pimples, when the number of pimples is too much, can be fused, forming a clear border, irregular shape of the yellowish-white plaque, some patients manifested as the inner wall of the mouth wrinkles. There are many reasons for the wrinkling of the inner wall of the mouth, and it is recommended that patients go to a regular hospital so as to find out the cause of the disease.