After quitting smoking causes mouth ulcers, consider the long-term smoking suddenly quit, resulting in plant nerve disorders, the formation of ulcers on fire in the mouth. This situation has a certain self-limiting, can gradually recover, this period of time to eat more vegetables and fruits, supplement vitamin C can accelerate the healing of ulcers. In addition, drink more water, eat less spicy and greasy food, if it affects the normal diet, you can use topical mouth ulcer paste or mouth ulcer spray, with the use of fire-removing drugs such as Niuhuang detoxification tablets, Huang Lian Shangqing tablets. Be sure to work and rest reasonably, avoid excessive strain, especially not stay up late, keep emotional stability, if the ulcer is still relatively large after two weeks, you should recommend a detailed examination at the Department of Stomatology.