Key Facts Mouth ulcers are sores that develop in the mouth and can be painful They can appear on the inside of the lips, cheeks, or under the tongue Most mouth ulcers are harmless and heal on their own Recurrent mouth ulcers can be a sign of an underlying health issue Avoiding certain foods and maintaining oral hygiene can help prevent mouth ulcers What are Mouth Ulcers? Mouth ulcers, also known as oral ulcers, are small, painful sores that develop on the inside of the mouth. These ulcers can appear on the tongue, inside the cheeks, lips, or at the base of the gums. They are typically round or oval…