Mouth ulcers, as the most common mucosal disease in stomatology, are self-limiting, and most mouth ulcers will resolve significantly within 1 week. The most common mouth ulcers are called aphthous mouth ulcers, also known as recurrent mouth ulcers, which are usually around 2-3mm in diameter and heal within 1-2 weeks. Relatively more serious mouth ulcers are generally called peritonsillar canker sores, and may reach a diameter of 1cm or even more Healing time is relatively long, but within 1 month there will be significant improvement. If the mouth ulcers continue to increase in size for more than 1 month, it is important to be alert to the occurrence of oral cancer.