Mouth ulcers can be red and darker than the surrounding normal mucosa when they are about to heal, or white, unhealed scar formation, as follows. 1. red: light oral ulcers do not form scarring when healing, about to heal in red, darker than the surrounding normal mucosa, with the complete healing of oral ulcers, the color of the lesion area is consistent with the surrounding mucosa. 2. white: heavy oral ulcers in the healing may form white scar, hard texture, can gradually become soft and disappear, the mucous membrane to return to normal color, or may not disappear. If the mouth ulcers do not improve, or other symptoms appear, it is recommended to go to the hospital in time to receive professional treatment.