There is no such thing as “what fruits are the worst for mouth ulcers”. Fruits can only provide vitamins and other nutrients, and cannot treat mouth ulcers. The ulcers are most likely due to xerostomia. Keratitis is related to genetics, immunity, mental factors, and nutrition. Studies have shown that deficiencies of iron, zinc, B vitamins, and vitamin C may trigger xerostomia. The most important thing to treat mouth ulcers is to localize anti-inflammatory, relieve oral pain and promote ulcer healing. Generally, you can eat more fruits and vegetables, add water appropriately, keep the bowel fluids flushing, ensure sufficient sleep, avoid excessive fatigue. You can use lidocaine gel to apply to the surface of the affected area, and at the same time use chlorhexidine gargle local anti-inflammatory. Watermelon cream powder is applied to the surface of the ulcer, which is conducive to the healing of the ulcer. Rehabilitation of new liquid can also be used externally to treat ulcers. At the same time can be appropriate oral vitamin C tablets and vitamin B tablets and so on. Once the mouth ulcers are diagnosed, it is recommended to consult a doctor in time to find out the cause and treat the cause.