A mouth ulcer, also known as an oral ulcer or canker sore, is a painful lesion that develops inside the mouth. These shallow, round or oval sores often have a white or yellowish center with a red border.
Mouth ulcers can be caused by various factors, including injury, stress, hormonal changes, certain foods, or underlying medical conditions.
They are not contagious and usually heal on their own within a week or two.
Over-the-counter treatments and home remedies can help alleviate discomfort and speed up the healing process.