Aphthous Ulcers: Causes, Symptoms, and Treatment Aphthous ulcers, also known as canker sores, are a common type of oral lesion that affects millions of people around the world. These painful, shallow sores can appear on the inside of the lips, cheeks, and tongue, and they can make eating, drinking, and talking uncomfortable. While they're not contagious or dangerous, they can be a nuisance and can affect the quality of life for those who suffer from them. In this article, we'll take a closer look at aphthous ulcers, their causes, symptoms, treatment, and prevention.What are Aphthous Ulcers?Aphthous ulcers are small, painful sores that appear on the inside of the mouth, including the lips, cheeks, and tongue. They can range in size from a few millimeters to several centimeters in diameter and are typically white or yellowish in color with a red border. They are not contagious and usually resolve on their own within one to two weeks, but they can be