Symptoms and Side Effects

Mouth Sores

Woman holds cheek in pain while standing in home living room, indicating a toothache or facial discomfort.

Mouth Sores (Stomatitis)

Cancer treatment—especially chemotherapy or radiation to the head and neck—can sometimes cause mouth sores (also called stomatitis). This condition involves swelling and redness in the lining of your mouth and may lead to painful sores. These can make eating, drinking, or swallowing difficult. Some people also develop a yeast infection in the mouth (called thrush), which is treatable.

The good news: there are effective ways to manage symptoms and care for your mouth at home.

Daily Mouth Care

Good oral hygiene can reduce pain and help prevent infections.

Brush your teeth with a soft nylon-bristle toothbrush

Rinse your toothbrush well in hot water after each use and store it in a cool, dry place.

Use a fluoride toothpaste that’s non-abrasive.

Rinse your mouth 30 minutes after meals and every 4 hours while awake–see the recipe below

Avoid mouthwashes that contain alcohol, which can worsen dryness and pain.

Avoid whitening toothpaste—it may contain hydrogen peroxide, which can irritate sores.

Gentle Mouth Rinse for Soothing Sores

Easy-to-make relief you can use throughout the day. Repeat 4 to 5 times a day, especially after meals and before bed.

What You’ll Need

1 teaspoon of salt or baking soda
1 glass (8 oz) of warm water

What to Do

Mix the salt or baking soda into the water
Swish the rinse gently in your mouth
Spit it out—don’t swallow

Managing Pain

If your mouth pain makes eating difficult, speak with your care team about options:

Ask about medicated rinses. Some can be applied 15–20 minutes before eating to relieve pain.
If your current treatment isn’t relieving pain, let your doctor know—stronger options are available.
Some prescription rinses may be frozen in an ice cube tray; sucking on the frozen cubes can help ease pain (check with your doctor first).

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Eating and Drinking Tips

Choose foods and drinks that are gentle on your mouth. Eat soft, moist foods like:

Mashed potatoes
Cooked vegetables
Noodles
Applesauce
Clear broth soups
Yogurt and cottage cheese

Try cold foods like yogurt or ice cream—they may soothe soreness
Drink plenty of fluids to stay hydrated. Using a straw can help reduce pain while drinking

Person sitting on a couch eating potato chips with coffee and remote control on a table nearby.

Things to Avoid:

High-acid juices (like orange, grapefruit, and cranberry)
Spicy or crunchy foods

If your symptoms get worse, contact your doctor. Also, watch for these signs and reach out to your care team If:

Drinking fluids is no longer possible
Medications can’t be swallowed
You notice white patches in your mouth or on your tongue (which could be thrush)
Pain is worsening or interfering with eating, drinking, or resting
Your temperature rises to 100.4°F or higher