Mouth ulcers all the time may be a sign of diseases such as leukoaraiosis, recurrent aphthous ulcers and oral cancer. 1. Leukoaraiosis: Leukoaraiosis is one of the causes of recurrent mouth ulcers. Leukoaraiosis is a chronic disease of the whole body, which not only leads to mouth ulcers that do not heal for a long time, but also leads to genital ulcers, and also leads to some abnormal lesions of the eyes and skin. 2. Recurrent Aphthous ulcers: recurrent Aphthous ulcers, also known as recurrent oral ulcers, recurrent Aphthous stomatitis, etc., is a kind of isolated, round or oval superficial ulcers, recurring periodically, and there is a certain degree of self-limitation, which is a relatively common oral mucosal disease. 3. Oral cancer: if long-term oral ulcers do not heal, the ulcer surface gradually expands, and conventional treatment is ineffective. In serious cases, there are lumps, nodules, repeated bleeding without obvious reasons, etc., then it is necessary to consider whether there is oral cancer. It is suggested that patients who have been suffering from mouth ulcers should consult doctor for diagnosis in time, find out the specific cause of the disease and deal with it actively, so as to avoid delaying the condition.