Mouth sores or ulcers are common. Most are benign. Recurring solitary ulcers are usually aphthous ulcers. These are benign ulcers the cause of which is unknown. Although they can be very painful, they usually heal spontaneously in a week or two and tend to recur throughout the year. In more severe cases, they can be treated with steroids either used topically or taken orally.
Multiple occurring ulcers are usually viral and the most common virus that causes them is the herpes simplex virus. They may be associated with fever blisters of the lips or herpetic ulcers elsewhere such as the nostrils. These can also be treated with topical medication and in more severe cases; antiviral drugs can be taken to prevent recurrences.
Mouth sores or ulcers as well as white patches that do not heal within a few weeks should be examined by a physician. In most cases a biopsy will be needed to properly diagnose the problem. If oral tumors are detected early, they are very manageable by surgical excision.