How to Manage Chemo Mouth Sores

Medically Reviewed by Arefa Cassoobhoy, MD, MPH on July 23, 2023
3 min read

Chemotherapy is a group of powerful medicines that can help slow or stop some cancers. But chemo can affect healthy cells in your body, too, like those that line the inside of your mouth and the kind that make saliva. The result may be dryness, tenderness, and sores inside your mouth that make it hard to eat or even talk.

They’re usually at their worst about 7 days into your treatment and typically go away around 10 to 14 days after your treatment ends. But there are some things you can do to help prevent the sores and manage them when you get them:

Use a soft-bristle toothbrush: It’s important to be gentle with the delicate tissue of your gums. You can make the bristles even softer by running them under hot water. Or you can go a step further and clean your teeth with simple cotton swabs or sponges made specially for your mouth.

Brush often, but lightly: Brush or clean your teeth after each meal and at bedtime. Whether you use a soft toothbrush or something else, take care to do it gently so you don’t damage the delicate tissue inside.

Floss every day: It helps keep your mouth clean and prevents the buildup of bacteria that can lead to infection. As with brushing your teeth, do it gently so you don’t damage your gums or cause bleeding. It's best to avoid areas that bleed or hurt, but it’s still important to floss the other areas.

Rinse your mouth: There are different solutions that may help. Ask your doctor what to use if you’re unsure. You can mix ¼ teaspoon of baking soda and ⅛ teaspoon of salt in 1 cup of warm water. Or use equal parts hydrogen peroxide and water. Rinse several times a day to help keep your mouth clean and cut down on sores. It’s a good idea to rinse with plain water afterward.

Get to the dentist before chemo: It’s a good idea to visit your dentist before you start treatment to fix any problems like gum disease or cavities. Tell your dentist about your cancer treatment, including radiation, which can also cause mouth sores, and whether you’ve had the sores before. They may be able to prescribe medication to help.

Keep your mouth moist: Drink plenty of water. You can suck on ice chips to stay hydrated, and the cold might help relieve some of the pain of mouth sores. It can also help to suck on sugar-free candies or chew sugarless gum.

Try a straw: For some people, drinking liquids through a straw helps keep liquids away from the lining of your mouth where it could irritate mouth sores. You can use it for soups as well as drinks.

Protect your lips: Use petroleum jelly, cocoa butter, or other mild lip balm to keep your lips moist. Consider something with sunscreen if you’ll be spending time in the sun.

Eat the right foods:

  • Cold foods like ice pops, frozen yogurt, and ice cream are easier on your mouth and may even soothe sore gums.
  • Soft, bland foods like mashed potatoes, oatmeal, and scrambled eggs are less likely to hurt your mouth.
  • Room temperature, or just slightly warm foods, rather than hot, are better for your tender mouth during chemo.



Avoid other foods:

  • Hard, crusty, dry items, like toast, potato chips, and pretzels
  • Sugary, spicy, or salty options like candy bars, salsa, or processed cheese
  • Acidic foods like fruits and juices (grapefruit, orange, tomato)

Use medication: There are several over-the-counter and prescription drugs that help numb the sores in your mouth. Other medications come in the form of a rinse that coats and protects the inside of your mouth before you eat or drink. You can even ask your doctor if a drug like palifermin (Kepivance), which helps grow cells inside your mouth, might be a good option for you.