If you have mouth ulcers, you should eat more apples, pears, watermelon, dragon fruit, cherry tomatoes, and kiwifruit. These are rich in vitamin C and complex B vitamins, which can effectively promote the healing of ulcers. This is because they can promote the synthesis of collagen, allowing the ulcer surface to heal quickly. Additionally, it is beneficial to consume more fibrous foods, such as green vegetables, leeks, and celery, to supplement dietary fibers and vitamins needed by the oral cavity. This can help in the recovery from mouth ulcers and also prevent frequent occurrences. It is advisable to avoid spicy and stimulating foods, consume fewer tropical fruits like lychee and longan, avoid staying up late, and maintain regular bowel movements.