Cancer: How to Prevent and Treat Mouth Sores

Certain cancer treatments can cause mouth sores called stomatitis. These painful ulcers appear on the tongue, inside the cheeks or lips, or in the throat.

These cancer treatments also cause your mouth to be very dry, which may make the sores bleed and make them heal more slowly. Mouth sores can get infected easily, especially when your body is already weak.

Signs of stomatitis

Mouth sores usually develop 1 or 2 weeks after certain cancer treatments. The sores are caused by these treatments. They are very painful.

The first sign is a pale, dry mouth. Then your mouth, gums, and throat may feel sore and get red and swollen. You also may have:

  • Bleeding from the sores.
  • White or yellow film on your mouth or tongue.
  • Pus or white patches in your mouth.
  • Increased mucus in your mouth.

Managing stomatitis

There are things you can do at home to help mouth sores feel better.

  • Drink plenty of fluids, and suck on ice chips or flavored ice pops. Some people find that it helps to drink through a straw.
  • Use lip balm to keep your lips moist.
  • Use a soft toothbrush.
  • Do not use mouthwash that has alcohol in it.
  • Gargle with warm water.
  • Eat soft foods such as ice cream, soft fruits, scrambled eggs, or pudding.
  • Soften food with butter, gravy, or broth.
  • Eat foods at room temperature or colder.
  • Stay away from spicy or acidic foods.

If these home treatments are not enough, your doctor can give you medicine to put on the sores. A mild mouthwash with antibiotics may prevent mouth infections. Ask your doctor about pain relief, medicine to put on the sores, or antibiotic mouthwash if you have mouth sores.

Preventing stomatitis

Start with a healthy mouth and teeth. Brush your teeth and gums with a soft toothbrush after every meal. Floss every day.

Before you start cancer treatment, have a dental checkup. If you wear dentures, ask your dentist to be sure they fit right. Take care of any cavities or other dental work.

Eat a healthy diet before, during, and after cancer treatment. A good diet will help your body cope with treatment and fight infection.

Radiation treatment for the mouth also can cause stomatitis. Sometimes daily radiation treatments may have to be delayed if the sores are severe.

When to call your doctor

If you get any of these symptoms of stomatitis, call your doctor:

  • You have small sores or ulcers in your mouth.
  • You have bleeding gums.
  • You have white patches in your mouth.
  • You have red or shiny areas in your mouth that last longer than 48 hours.

When is stomatitis an emergency?

  • You have severe pain.
  • You cannot eat, drink, or sleep.
  • You have a fever.