Mouth sores are areas that might look like little cuts or ulcers in the mouth (also known as mucositis or stomatitis). This is because certain kinds of cancer treatment can damage the cells that line the mouth, throat, and gastrointestinal (GI) tract. This causes sores or ulcers to develop in the affected areas. In some cases, the soreness and sores may extend into the throat and farther down into the gastrointestinal (GI) tract, making eating and swallowing painful. Mouth sores can appear 1 to 2 weeks after treatment starts and may come and go if treatment is given in cycles. Some treatments are more likely to cause mouth sores than others.
The treatments and other factors that most commonly cause mouth sores include:
Healing may take 2 to 4 weeks when treatment completely ends. Mouth sores can be very painful and lead to dehydration, poor eating, and weight loss. They can also be costly to treat if they cause serious problems.
Dental checkups before treatment, and especially before head and neck radiation therapy, can help prevent and minimize mouth sores. Dentists can help show you how to care for your mouth and can treat cavities or oral infections before cancer treatment starts. It's important to talk to your cancer care team about the best treatment for your situation. Although more research is needed to find the best treatment plan to manage mouth sores and pain, some options might include good mouth care and mouth rinses, reducing treatment doses, cryotherapy, or laser therapy.
Good mouth care is key to help reduce the risk or severity of mouth sores. Using a soft toothbrush or foam swab can help keep the mouth clean and reduce the risk of injuring your gums and lining of the mouth. If you use dental floss, ask your doctor if you should stop or if you can continue to floss.
Certain types of rinses can help to keep your mouth clean and can help soothe discomfort. Ask your doctor which type of rinse may be best for your situation. For example, baking soda, salt water, or saline rinses might be recommended. Mouth rinses with antibiotic agents or steroids might be recommended, depending on how severe the mouth sores are.
Benzydamine (an anti-inflammatory drug) may help prevent mouth sores in people getting radiation treatment to the mouth or throat. Morphine rinses may help relieve pain from mouth sores in this same group of people. Dexamethasone (a steroid) has been used in mouth rinses to help with cleansing and discomfort.
Another type of mouth rinse, often referred to as "magic mouthwash" might be recommended by your doctor. Magic mouthwash is a mixed medication mouthwash that combines a few different medicines. But, there is not one single combination that's used by all doctors, and some experts don't recommend a combination. Some common ingredients of magic mouthwash include diphenhydramine, viscous lidocaine, aluminum hydroxide, nystatin, and corticosteroids.
Because some mouth rinses and home remedies might be harmful or make mouth sores worse, talk to your cancer care team before using or making any rinses at home, to be sure it's right for your situation.
Certain vitamins or supplements may be helpful for mouth sores, but it's important to talk to your doctor before using any.
Prescribed medication for mouth sores might include:
When cryotherapy is used, the patient sucks on ice chips before, during, and after short infusions of certain chemotherapy treatments. Some studies have shown this to help prevent mouth sores by decreasing tissue blood flow and limiting high chemical exposure from treatment.
Research shows that using low-level laser therapy (LLLT) may help prevent mouth sores that can result from stem cell transplant and radiation to the head and neck. More studies are being done to find out if low-level laser therapy can be used in other types of treatment.
Check your mouth twice a day using a small flashlight, mirror, and a padded Popsicle stick. If you wear dentures, take them out before you check your mouth. Tell your health care team if your mouth looks or feels different or if you notice changes in how things taste.
Talk to your cancer care team about a plan for mouth care that is right for you.
For example, your cancer care team might recommend doing mouth care 30 minutes after eating and every 4 hours while you’re awake by using a soft toothbrush, non-abrasive toothpaste, and certain kind of alcohol-free mouthwash or special mouth rinse. Ask about whether you should floss or not. If you have dentures, you may be instructed to remove and clean your dentures between meals on a regular time schedule, and to store them in cleansing soak.
Other tips that might help include:
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.
Brown C. Mucositis. In Brown CG, ed. A guide to oncology symptom management. 2nd ed. Pittsburgh, PA: Oncology Nursing Society; 2015: 469-482.
Elad S, Cheng KKF, Lalla RV et al. MASCC/ISOO clinical practice guidelines for the management of mucositis secondary to cancer therapy. Cancer. 2020;4423-4431.
Fall-Dickenson J, Cordes S, Berger AM. Oral complications. In DeVita VT, Lawrence TS, Rosenberg SA, eds. DeVita, Hellman, and Rosenberg’s Cancer: Principles and Practice of Oncology. 11th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2019:-2094-2108.
Majithia N, Hallemeier CL, Loprinzi, CL. Oral complications. In Niederhuber JE, Armitage JO, Kastan MB, Doroshow JH, Tepper JE, eds. Abeloff’s Clinical Oncology. 6th ed. Philadelphia, PA: Elsevier; 2020:607-620.
Oncology Nursing Society (ONS). Symptom interventions: Mucositis. Accessed at https://www.ons.org/pep/mucositis on January 3, 2020.
Last Revised: September 24, 2021
American Cancer Society medical information is copyrighted material. For reprint requests, please see our Content Usage Policy.