Preventing and Healing Mouth Sores During Cancer Treatment

Mouth sores are a common side effect of chemotherapy and radiation to the head or neck. These painful ulcers can make eating, drinking, and talking uncomfortable. They may appear a few days into treatment and usually heal within two to three weeks after treatment ends. Fortunately, there are steps you can take to prevent them and ease the pain.

Why Cancer Treatment Causes Mouth Sores

Cancer medications damage the lining of your mouth, making it more vulnerable to sores and infection. The damage can happen quickly, sometimes within days of treatment starting.

Prevention Starts Before Treatment

Talk to your oncology team before treatment begins:

• Schedule a dental checkup and cleaning

• Have your dentist fix any cavities or damaged teeth

• Ask about fluoride treatments

• Ask about a special mouthwash your team recommends

Taking care of your teeth before treatment starts reduces the risk of mouth sores.

Daily Oral Care

During treatment, be gentle with your mouth:

• Use a soft-bristled toothbrush

• Brush gently twice daily with fluoride toothpaste

• Rinse with salt water or baking soda rinse several times daily

• Floss gently once a day

• Avoid mouthwash with alcohol (it can dry out your mouth)

• Don't use toothpicks or hard dental floss

Foods and Drinks to Avoid

Certain foods irritate mouth sores:

• Hot foods and beverages

• Spicy foods

• Citrus fruits and juices

• Tomato-based foods

• Hard or crunchy foods

• Alcohol

• Tobacco products

Foods That Are Gentle on Your Mouth

Try these instead:

• Soft fruits like bananas and applesauce

• Yogurt and smoothies

• Mashed potatoes or sweet potatoes

• Scrambled eggs

• Soups and broths (lukewarm)

• Pudding and ice cream

• Soft cooked vegetables

• Protein shakes

Eat smaller meals more often if swallowing is painful.

Pain Relief Options

If mouth sores develop:

• Rinse with salt water or a baking soda rinse several times daily

• Ask your doctor about numbing gels or rinses

• Use ice chips or ice pops to soothe pain

• Drink through a straw to avoid contact with sores

• Eat cold foods when possible

• Take pain medication if prescribed

Never use over-the-counter products without asking your care team first, as some can interfere with treatment.

When to Call Your Doctor

Contact your care team if:

• Sores are severe or spreading

• You have difficulty eating or drinking

• You develop a fever

• Sores don't improve after treatment ends

• You notice signs of infection (increased redness, pus, or swelling)

Your doctor may recommend special medications or rinses to speed healing or reduce pain.

Take Care of Your Mouth

Mouth sores are temporary, but they need attention during treatment. Being proactive with oral care and gentle with your mouth helps prevent severe sores. Keep your care team informed about any mouth problems so they can help you manage them.

 Written By: Carolyn Vandenbroek, MSDM

Reviewed By: Srilata Gundala, MD

Disclaimer: This blog provides general educational information and is not a substitute for medical or psychological advice. Always speak with your healthcare provider and mental health professionals for guidance specific to your situation.