Aphthous ulcer refers to the common mouth ulcer, also known as recurrent mouth ulcer, Aphthous is a foreign pronunciation. The typical symptoms are often a yellow indurated pseudomembrane in the middle of the ulcer, surrounded by a slight redness and swelling. However, this ulcer is typically painful and can be very intense. It is self-limiting and will heal spontaneously in about a week to two weeks, but it is also clinically difficult to cure because of its strong recurrence. For the cause of this ulcer, there is no definite cause, but it is generally believed to be related to immune factors, genetic factors, nutritional deficiencies and hormonal regulation, endocrine factors, etc. For its treatment, it also requires comprehensive treatment based on the cause.