Vitamin C is an adjunct to mouth ulcer healing, but should not be used singly as a therapeutic agent. Adverse reactions and contraindications should be noted in its use. Vitamin C is involved in antibody and collagen formation in the body, and has a certain effect on tissue repair. Some studies have pointed out that, compared with the simple topical use of aluminum thioglycollate, acyclovir, metronidazole and other antibacterial, antiviral and disinfectant antiseptic drugs, the addition of vitamin C can effectively shorten the duration of the disease and promote the healing of ulcer wounds. Vitamin C is often used as an adjunctive therapeutic agent for oral ulcers. There is no authoritative literature stating that vitamin C alone can treat mouth ulcers. Vitamin C is currently used primarily for the prevention of scurvy and as an adjunct to the treatment of diseases such as purpura. If symptoms such as diarrhea, headache, frequent urination, or stomach cramps occur while taking the medication, it is recommended that the medication be discontinued and medical attention be sought. The drug must be used in accordance with the doctor’s instructions, long-term use of the drug or a large number of drugs may cause scurvy, urinary stones and other diseases. Caution is advised in cases of pregnancy, lactation, cysteinuria, gout, hyperoxaluria, thalassemia, sickle cell anemia, diabetes mellitus. The appearance of mouth ulcers do not heal for a long time, or repeated mouth ulcers, it is recommended to go to the hospital in time; the above drugs need to be used under the guidance of clinicians.