The clinical manifestations of recurrent aphthous ulcers include the following: i. The location of the ulcers is not fixed and they occur anywhere in the mouth, mostly small ulcers with a red halo around the ulcer and painful symptoms. Second, the middle of the ulcer is mostly depressed, the pain is severe, most of them affect eating or pain after eating. The ulcers are variable in location, with one ulcer recovering in about half a month or a week, but reappearing in another location. Such recurrent ulcers are aphthous ulcers. Patients who develop such ulcers should pay attention to a balanced diet and vitamin supplementation.