Ulcers are generally referred to as mouth ulcers. Mouth ulcers are associated with vitamin B₁, vitamin B₂, vitamin B₁₂, and folic acid deficiencies. In addition to nutritional deficiencies causing mouth ulcers, infections, endocrine changes, and dietary factors may cause mouth ulcers. Mouth ulcers are associated with nutritional deficiencies of vitamin B₁, vitamin B₂, vitamin B₁₂, and folic acid, which are components of coenzymes and play an important role in metabolism. It can also be caused by deficiencies of trace elements such as zinc, iron and selenium. Inadequate intake of vitamins and deficiencies of trace elements tend to cause recurrent mouth ulcers. In addition to nutritional deficiencies leading to mouth ulcers, they may also be caused by infections, endocrine changes, damage to the oral mucosa, and dietary factors. It can be treated with medications such as 0.05% chlorhexidine gargle, compound chlorhexidine solution, cediriodine tablets, and diazepam chloride. If you need to use drugs, you need to use under the guidance of a doctor. If the ulcer is difficult to heal for a long time, or other discomforts occur, you should consult a doctor in time.