Mouth Sores

Oral lesions (mouth sores) make it painful to eat and talk. Two of the most common recurrent oral lesions are fever blisters (also known as cold sores) and canker sores. Though similar, fever blisters and canker sores have important differences.

Fever blisters are fluid-filled blisters that commonly occur on the lips. They also can occur on the gums and roof of the mouth (hard palate), but this is rare. Fever blisters are usually painful; pain may precede the appearance of the lesion by a few days (prodromal phase).  The blisters rupture within hours, then crust over. They last about seven to ten days.  Fever blisters result from a herpes simplex virus type I that becomes active. This virus is latent (dormant) in afflicted people, but can be activated by conditions such as stress, fever, trauma, hormonal changes, and exposure to sunlight. When lesions reappear, they tend to form in the same location.  It is felt that treatment with antiviral should be started during the prodromal phase to hasten healing and reduce viral shedding (the source of contagion).  Cold sores are most contagious when oozing blisters are present.  The virus can also be spread in the absence blisters by sharing eating utensils, razors and towels, as well as kissing.  Note that this is not the same as the herpes virus associated with genital herpes.

Canker sores (also called aphthous ulcers) are different than fever blisters. They are small, red or white, shallow ulcers occurring on the tongue, soft palate, or inside the lips and cheeks; they do not occur in the roof of the mouth or the gums. They are quite painful, and usually last 5-10 days.

Eighty percent of the U.S. population between the ages of 10 to 20, most often women, get canker sores. The best available evidence suggests that canker sores result from an altered local immune response associated with stress, trauma, or irritation. Acidic foods (e.g., tomatoes, citrus fruits, and some nuts) are known to cause irritation in some patients.  Unlike cold sores, canker sores pose no risk to others.  There is no definitive treatment other than time.  Some studies have suggested that warm salt water rinses may be the most valuable treatment although a large range of medications, some of which have significant side effects, have been used, especially in more refractory and frequent attacks.  When a sore is enlarging or failing to heal after two weeks or occurs on a bony surface, see your doctor.

Other findings in the mouth include the following:

  • Thrush is a yeast infection that can be seen as white plaques on moist surfaces in the oral cavity and throat, common among diabetics, users of oral and/or inhaled steroids, or during or after courses of antibiotics.  It is also seen in patients with immune compromise.  Although it is usually fairly simple to diagnose and can often be treated topically with rinses or lozenges, sometimes it requires longer treatment with antifungal medication.
  • Leukoplakia, meaning white plaque in Greek is a whitish patch that forms on the inside of the cheeks, gums, or tongue. These patches are caused by excess cell growth and vary from thin to relatively thick.  Not all white patches are as concerning as others, however, a history of tobacco and/or alcohol should raise red flags. They can result from irritations such as ill-fitting dentures or the habit of chewing on the inside of the cheek. Some are lacy appearing patches, termed lichen planus, on the inside of the cheeks associated with a poorly understood immune response.  While these are not necessarily as concerning, they should still be monitored.  Leukoplakia, and more concerningly erythroplakia (red patches) can progress to cancer.
  • Torus palatinus (or mandibularis) is a hard bony growth, sometimes with multiple lobules, in the center of the roof of the mouth (or inside the lower gums, usually bilaterally). These are very common and rarely needs treatment unless it interferes with the fitting of a denture.
  • Oral cancer – It may appear as a white or red patch of tissue in the mouth, or a small ulcer that looks like a common canker sore. Other than the lips, the most common areas for oral cancer to develop are on the tongue and the floor of the mouth. Other symptoms include a lump or mass that can be felt inside the mouth or neck; pain or difficulty in swallowing, speaking, or chewing; any wart-like mass; hoarseness that lasts for more than two weeks; or any numbness in the oral/facial region.

If you or your dentist have any question about a lesion in your mouth that fails to go away in a few weeks, seek the attention of an otolaryngologist.