Mouth Sores

Chemotherapy and radiation therapy cause inflammation of the tongue, lips, mouth, throat, and gastrointestinal tract. This often leads to mouth sores and discomfort when eating, drinking, and sleeping.

Some cancer treatments lower the body's ability to fight infection. This makes it important to take good care of the mouth to avoid infection. Swelling in the mouth and tongue may also make it difficult to swallow and breathe.

Call the clinic or hospital right away if any of these symptoms occur:

  • Blood in the mouth
  • Difficulty swallowing
  • Mouth dryness
  • Uncontrolled pain
  • White patches or sores on the lips, gums, tongue, or mouth

What patients can do:

  • Avoid alcoholic drinks.
  • Avoid mouthwashes that contain alcohol or peroxide.
  • Avoid spicy, sour, or crunchy foods.
  • Keep flossing at least once a day, but avoid areas that are bleeding or sore.
  • Rinse the mouth with warm salt water every hour or as desired (do not swallow).
  • Suck on hard candy or chew sugar-free gum to stimulate saliva production.
  • Take pain medication as instructed by the doctor.
  • Eat foods that are soft and easy to swallow. A registered dietitian in the Linda B. and Robert B. Wiggins Wellness and Integrative Health Center can suggest some good choices.
  • Try moisturizing mouth rinses such as Biotene (found at local stores).
  • Use a toothbrush with soft bristles.
  • Use lip balm.


  • Drink plenty of liquids. Using a straw may help.
  • Choose soft, moist foods.
  • Cook food until soft and tender.
  • Use cold foods to soothe a sore mouth or throat.
  • Avoid foods such as citrus fruits and juices, spicy or salty foods, and rough, coarse, or dry foods.
  • Rinse your mouth often to remove food and bacteria. Ask your dentist about cleaning products for the teeth and gums.
  • Ask your health care provider if any medicine(s) can help.