Mouth sores may be symptoms of a disease or disorder. A dentist should examine any mouth sore that lasts a week or longer.

Canker sores

Small ulcers with a white or gray base and a red border. Unlike cold sores, canker sores appear inside the mouth. And, they are not contagious. There may be only one canker sore or several and they often return. Their exact cause is uncertain but some experts believe that immune system problems, bacteria or viruses may be involved.

Fatigue, stress or allergies can increase the likelihood of a canker sore. A cut caused by biting the cheek or tongue, or reactions from hot foods or beverages may contribute to canker sore development. Intestinal problems, such as ulcerative colitis and Crohn’s disease, also seem to make some people more susceptible.

Treating Canker Sores. They usually heal on their own after a week or two, but an outbreak may occur. Over-the-counter topical anesthetics and antimicrobial mouthrinses may provide temporary relief. Stay away from hot, spicy or acidic foods that can irritate the sore. Antibiotics and some oral bandages can reduce secondary infection.

Cold sores

Annoying and definitely unsightly, cold sores, also called fever blisters or Herpes simplex, are groups of painful, fluid-filled blisters. They often erupt around the lips and sometimes under the nose or around the chin. Cold sores caused by herpes virus type 1 are very contagious. The initial infection (primary herpes), which often occurs before adulthood, may be confused with a cold or flu and can cause painful lesions to erupt throughout the mouth.

Once a person is infected with primary herpes, the virus stays in the body and causes occasional attacks. For some people, the virus remains inactive. Recurring herpes lesions look like multiple tiny fluid-filled blisters (cold sores) that most commonly appear around the edge of the lips. An attack may follow a fever, sunburn, skin abrasions or emotional upset.

Treating cold sores. Cold sore blisters usually heal in a week by themselves. Over-the-counter topical anesthetics can provide some relief. Prescription antiviral drugs may reduce these kinds of viral infections.