Canker Sores

Canker sores are small, painful, shallow ulcers in the mouth. Canker sores usually recur. A short time or a long period may elapse between outbreaks. Canker sores are not contagious.

Causes

The cause of canker sores is not known. Causative factors may include:
  • Abnormal immune response against the surface tissue of the mouth
  • Genetic predisposition
  • Dietary allergies or sensitivities to certain foods, such as chocolate, nuts, and citrus fruits
  • Injury to mouth tissue (possibly unnoticed)
  • Nutritional deficiencies

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.
  • Family history of canker sores
  • Nutrient malabsorption
  • Prolonged fever
  • HIV infection or AIDS
  • Stress
  • Women's cyclic hormonal changes

Symptoms

Symptoms occur in stages and include:

Prior to the sore:
  • Tingling or burning sensation
  • Red bump or bumps
Once the sore has appeared:
  • One or more small ulcers inside of the lips or cheeks, on the palate or under the tongue
  • Shallow open area
  • White, yellow, or gray coating
  • Raised, red rim
  • Pain, possibly making eating or talking difficult

Diagnosis

The doctor will ask about your symptoms and medical history, and examine the sores. If canker sores recur frequently, the doctor may look for an underlying cause, such as a vitamin or mineral deficiency or immunologic condition. If a sore does not heal, a small sample (called a biopsy) may be taken. The sample tissue will be examined under a microscope to look for cancer cells.

Treatment

Minor, small canker sores usually heal on their own in about 1-2 weeks. Call your doctor if they:
  • Persist for longer than 1-2 weeks; or
  • Are so big that they interfere with eating; or
  • Are associated with a fever
Large sores may take weeks or months to heal and should be checked by a doctor to rule out other conditions that cause similar sores. If an underlying condition is causing frequent sores, the doctor will offer advice to correct the underlying physical or emotional condition.

Treatment includes:

Self-Care
 
Over-the-counter rinses and pain relievers, such as Orabase or Zilactin-B, may help relieve discomfort. Rinsing your mouth for one minute with a mixture of equal parts Milk of Magnesia and Benadryl Allergy liquid may relieve the pain. Do not swallow this mixture. Spit it out. If you have a lot of pain from the sore, try an over-the-counter pain medication taken by mouth.

Take steps to prevent further injury to the mouth. A diet of soft foods may be less irritating while the sore heals. Avoid salty foods, citrus fruits, and foods with sharp surfaces. Do not talk while chewing. Use a toothbrush with soft bristles.

Medication

The doctor may prescribe medication to relieve the discomfort and promote healing. Continue using the medication for as long as the doctor directs, even if the sore feels better. Medications include:
  • Steroid ointments applied to the sore to reduce inflammation
  • Triamcinolone in Orabase Fluocinonide – Put a thin film on the sore three or four times daily.
  • Dexamethasone elixir – Rinse with this liquid then spit it out.
  • Pain relieving drugs to apply to the sore
  • Lidocaine – applied before meals
  • Steroids taken by mouth (rarely needed)
  • Prednisone
  • Mouthwash to decrease the risk of developing a secondary bacterial infection
  • Tetracycline – Hold in your mouth for several minutes then spit out.
  • Chlorhexidine gluconate – Rinse with this product after brushing your teeth then spit it out.
  • Carbamide peroxide gel – Protects against normal bacteria found in the mouth and keeps the sore clean.
Treating the Underlying Condition

Treating an underlying medical condition that causes canker sores may eliminate future outbreaks.

Stress Management

Learn and practice stress-management and relaxation techniques.

Prevention

Canker sores may be more likely to recur in people who have a family or personal history of the aphthous ulcers. Prevention focuses on avoiding injury to the surfaces of the mouth and correcting any underlying conditions. Suggestions include:
  • Avoid foods with sharp surfaces.
  • Avoid foods associated with your outbreaks.
  • Do not talk while chewing.
  • Use a toothbrush with soft bristles.
  • Consider learning and practicing stress-management techniques.