Mouth ulcers are related to vitamin deficiencies, such as vitamin B1, B2, B6, and B12 deficiencies, all of which can cause mouth ulcers, and oral vitamin B12 has a role in mouth ulcers. However, oral ulcers are also related to other causes, only taking oral vitamin B12 may not be able to effectively treat, but also can choose local medicine and systemic medicine. 1. Local medication: choose ice boron powder or watermelon cream spray on the ulcer surface, you can also choose 0.1% ~ 0.2% chlorhexidine gluconate solution, 0.5% povidone-iodine solution or compound boric acid solution gargling, cedirizine and so on. 2. Systemic medication: you can choose oral transfer factor, levamisole and so on to enhance the body’s immunity, can also reduce the recurrence of mouth ulcers. In order to reduce the occurrence of mouth ulcers, eat more fresh fruits and vegetables, more outdoor exercise, enhance immunity. If the symptoms of mouth ulcers are serious, you need to consult a doctor in time and use medication under the guidance of a physician.