Mucositis During Cancer Treatment

Mucositis means painful sores and swelling in the lining of the mouth or throat during cancer treatment. This page is for patients and caregivers who want to know why it happens, how long it lasts, how it is treated, and when to call for help.

The National Cancer Institute defines it precisely: "Oral mucositis is an inflammation of mucous membranes in the mouth. It usually appears as red, burn-like sores or as ulcer-like sores in the mouth."

You will also hear the word stomatitis. NCI says the two terms "are often used in place of each other, but they are different." Stomatitis is broader. It covers inflammation of the mucous membranes "and other tissues in the mouth." That means the gums, the tongue, the roof and floor of the mouth, and the inside of the lips and cheeks.

This page covers the clinical picture. Why does mucositis happen? How long does it last? How is it treated? For daily mouth care, dental visits, and eating, see the companion page on mouth sores and dental problems.

Chemotherapy and radiation therapy work by slowing or stopping the growth of fast-growing cells. NCI explains the consequence: "Normal cells in the lining of the mouth also grow quickly, so anticancer treatment can stop them from growing, too. This slows down the ability of oral tissue to repair itself by making new cells."

NCI states that "mucositis may be caused by either radiation therapy or chemotherapy." Radiation can also directly damage oral tissue, salivary glands, and bone. NCI's side-effect page adds that "some types of chemotherapy and immunotherapy can also harm cells in your mouth, throat, and lips." Both treatments also upset the normal balance of bacteria in the mouth.

How long mucositis lasts depends on what caused it. NCI gives three patterns:

• Chemotherapy. "Mucositis caused by chemotherapy will heal by itself, usually in 2 to 4 weeks if there is no infection."
• Radiation therapy. It "usually lasts 6 to 8 weeks, depending on how long the treatment was."
• High-dose chemotherapy or chemoradiation for stem cell transplant. "Mucositis usually begins 7 to 10 days after treatment begins, and lasts for about 2 weeks after treatment ends."

The American Cancer Society describes a similar arc. Mouth sores "can appear 1 to 2 weeks after treatment starts and may come and go during treatment."

NCI lists four problems mucositis may lead to: pain, infection, bleeding, and "trouble breathing and eating." On bleeding it draws a distinction worth knowing. Bleeding occurs "in patients receiving chemotherapy." But "patients receiving radiation therapy usually do not have bleeding."

Infection is the reason the care team watches this closely. NCI explains how it happens: "oral mucositis breaks down the lining of the mouth, which lets bacteria and viruses get into the blood. When the immune system is weakened by chemotherapy, even good bacteria in the mouth can cause infections." And crucially: "As the white blood cell count gets lower, infections may occur more often and become more serious. Patients who have low white blood cell counts for a long time have a higher risk of serious infections."

Mucositis can also change your treatment. NCI notes that "sometimes treatment doses need to be decreased or treatment stopped because of oral complications."

Because mucositis can affect your treatment, your team will keep track of how bad it is. NCI's patient summary does not publish a severity grading scale. So this page will not invent one. What NCI does say is that treatment "depends on your white blood cell count and how severe the mucositis is." Ask your team how they are tracking it, and what would change the plan.

Prevention. NCI reports that "swishing ice chips in the mouth for 30 minutes, beginning 5 minutes before patients receive fluorouracil, may help prevent mucositis." Patients receiving high-dose chemotherapy and stem cell transplant "may be given medicine to help prevent mucositis or keep it from lasting as long."

Cleaning the mouth. NCI advises cleaning teeth and mouth "every 4 hours and at bedtime." Clean more often if mucositis gets worse. Use a soft-bristle toothbrush and replace it often. Use mild rinses or plain water. Frequent rinsing "removes pieces of food and bacteria from the mouth, prevents crusting of sores, and moistens and soothes sore gums and the lining of the mouth."

Do the sores begin to crust over? NCI describes a rinse of three percent hydrogen peroxide mixed with an equal amount of water or saltwater. There is a firm limit on it: "This should not be used for more than 2 days because it will keep mucositis from healing."

Pain. Topical medicines come first. Rinse your mouth before applying them. NCI carries an important warning about painkillers: "Nonsteroidal anti-inflammatory drugs (NSAIDS, aspirin-type painkillers) should not be used by patients receiving chemotherapy because they increase the risk of bleeding." NCI notes two further options. First, "zinc supplements taken during radiation therapy may help treat pain caused by mucositis." Second, alcohol-free povidone-iodine mouthwash "may help delay or decrease mucositis caused by radiation therapy."

Call 911 or go to the nearest emergency department if you have trouble breathing, or if you vomit blood or coffee-ground material.

If you are on chemotherapy, a stem cell transplant, CAR T, or have low white blood cells, call your care team right away, day or night, for:

• Mouth sores or mouth pain that makes it hard to eat, drink or sleep.
• A temperature of 100.4 °F (38 °C) or higher.
• Chills or a sore throat.
• Burning when you urinate.
• Redness at a catheter site.
• Any other sign of infection.

A normal temperature is not permission to wait. CDC says fever may be the only sign of infection, and that you should call your doctor immediately at 100.4 °F (38 °C) or higher. NCI lists a slightly higher number, 100.5 °F, on its mouth and throat page. This page uses the lower number to be safe. Use the number your own team gave you if it is lower.

Also tell your care team about:

• Bleeding from the gums.
• White patches in the mouth.
• Redness or shininess in the mouth that lasts more than 48 hours.
• Trouble taking your medicines because of sores.
• Not being able to eat or drink for two days.

ACS asks people to report these. If your team gave you an after-hours number, use it. Do not wait for your next appointment.

• National Cancer Institute — Oral Complications of Cancer Therapies (PDQ), Patient Version: https://www.cancer.gov/about-cancer/treatment/side-effects/mouth-throat/oral-complications-pdq
• National Cancer Institute — Mouth and Throat Problems: https://www.cancer.gov/about-cancer/treatment/side-effects/mouth-throat
• CDC — Watch Out for Fever: https://www.cdc.gov/cancer-preventing-infections/patients/fever.html
• American Cancer Society — Mouth Sores and Pain: https://www.cancer.org/cancer/managing-cancer/side-effects/eating-problems/mouth-sores.html

Helpful next pages include Mouth Sores & Oral Care During Cancer Treatment, Side Effects of Cancer Treatment, Low White Blood Cells During Chemotherapy, and Supportive Care.