Mouth Sores

Abramson Cancer Center of the University of Pennsylvania
Last Modified: November 1, 2001

Mouth sores are small cuts or open ulcers that can occur anywhere in the mouth. The sores may be bright red or may have small white patches in the middle, and sometimes may bleed. Patients receiving radiation therapy to the head and neck area may develop mouth sores. Other causes include chemotherapy, infection, dehydration, poor mouth care, oxygen therapy, excessive use of alcohol and/or tobacco, and lack of protein in the diet.

There are a variety of things that you can do to prevent mouth sores, or to minimize pain or discomfort and promote healing should they occur:

  • Check the entire mouth twice a day using a small flashlight and tongue blade. If you wear dentures, remove them and look under the plates. Report any changes in appearance, taste or feeling to your radiation oncologist or nurse.
  • Perform the following mouth care 30 minutes after eating and every 4 hours while awake:
    • Using a soft nylon bristle toothbrush, gently brush the teeth. If the toothbrush causes pain or discomfort, try soaking it in hot water to further soften the bristles. If still painful, use foam toothettes or wrap gauze around a Popsicle(r) stick and gently swab the teeth and gums.
    • Rinse your toothbrush well after each use and store in a cool, dry place.
    • Use a non-abrasive toothpaste or solution of 1 teaspoon baking soda in 2 cups water. Avoid toothpastes that contain additional ingredients such as whiteners.
    • Remove and clean dentures.
    • Keep lips moist with K-Y jelly or Chapstick®. Do not use Vaseline® because the oily base may promote infection.
  • Avoid products that may dry the mouth, irritate the mouth and gums, or cause pain and discomfort.
    • Do not use commercial mouthwashes that may contain alcohol.
    • Do not use dental floss.
    • Do not use lemon or glycerin swabs.
    • Do not use medium or coarse bristle toothbrushes.
  • Gently rinse mouth before and after meals and at bedtime with warm water or a solution suggested to you by your radiation oncologist or nurse. Swish the solution around the mouth, gently gargle, then spit out.
  • Make dietary changes to prevent mouth sores, decrease pain and discomfort, and promote healing.
    • Increase your fluid intake. Try to drink 3 quarts of fluid per day, unless your radiation oncologist or nurse tells you not to do so.
    • Include foods high in protein such as dried beans, poultry, eggs, peanut butter, meat, fish, and dairy products, such as milk, cheese and yogurt.
    • Avoid hot, spicy, greasy or fried foods.
    • Avoid alcohol.
    • Avoid citrus fruits and juices such as oranges, lemons, limes and tomatoes. Try apricots, pears or peaches instead.
    • Avoid hard or coarse foods such as crusty breads, crackers, raw vegetables, potato chips, tortilla chips and pretzels.
    • Avoid carbonated beverages.
    • Eat whenever you are hungry, even if it's not a mealtime.
    • Eat smaller, more frequent meals throughout the day, rather than three large meals. Create a nice environment when eating to stimulate your appetite.
  • Take special precautions with dentures.
    • Remove dentures whenever possible to expose the mouth and gums to air.
    • If weight loss occurs, dentures may become loose and slip. Do not wear loose-fitting dentures that may irritate the mouth and gums.
    • If mouth sores are severe, do not wear dentures.
  • Do not smoke cigarettes, cigars or pipes. Do not using chewing tobacco.

When Should I Call My Doctor?

Mouth sores should not be ignored, since they can cause a decrease intake of food and fluid, can be a source of infection, and can cause pain and discomfort. Call your doctor immediately if you have any one or more of the following:

  • redness or shininess in the mouth that lasts for more than 48 hours.
  • when you first notice any type of cut or sore in the mouth.
  • bleeding gums.
  • oral temperature above 100.5o degrees, chills or sweats.
  • weight loss of 5 pounds or more since the mouth sores began.

How are Mouth Sores Treated?

To promote healing of mouth sores, your radiation oncologist or nurse may recommend that you rinse with special solutions.

If mouth pain is severe or interferes with eating, your radiation oncologist may prescribe a medication which temporarily numbs the mouth. In addition, if weight loss from poor intake of food and fluids is a concern, you may be referred to one of our nutritionists.

If necessary, your radiation oncologist may decide to delay further treatments until the mouth sores have healed.

If you have any questions about mouth sores, or need additional information and direction, ask your doctor or nurse.

From the National Cancer Institute