It is not recommended to use vitamin C directly on the topical application of mouth ulcers because vitamin C is an acidic substance and topical application may cause relatively large stimulation and local pain and discomfort. Mouth ulcers are caused by a variety of reasons, related to mechanical injury, underlying diseases, immune dysfunction, neurological and mental factors. Of course some of them may be related to vitamin deficiency, such as lack of B vitamins, vitamin C, trace elements of zinc, etc. Vitamin C is in principle helpful for the healing of mouth ulcers and can promote local collagen, connective tissue and blood vessel repair. In some mouth ulcer treatment drugs, such as topical mouth ulcer patches actually contain vitamin C ingredients, but it is generally not recommended to take vitamin C tablets or injectable products directly and apply directly to mouth ulcers because the higher concentration may lead to local irritation. Vitamin C is an acidic substance of ascorbic acid and is not suitable for use directly on the ulcer surface, so it is recommended to use adult medicines, commonly used for the treatment of Italian can paste or mouth ulcer paste, but also oral supplementation of vitamin C, which may be relatively more effective and safer.