Mouth sores due to cancer treatment

What is mucositis (mouth sores)?

Mucositis is the painful inflammation and ulceration of the mucous membranes lining the digestive tract, usually as an adverse effect of chemotherapy and radiotherapy treatment for cancer.

Symptoms of mouth sores

Signs of mouth ulcers include pain and redness at the site of the lesion. Diagnosis is usually performed by examination of the appearance of the lesion or further tests, such as a blood test or biopsy. Treatment involves oral hygiene, topical preparations, and avoidance of irritating substances on or near the lesion.

Causes of mouth sores

There are several possible causes of mouth sores related to cancer and cancer treatment.

  • Chemotherapy. Up to 40% of people receiving chemotherapy experience mouth sores.
  • Head or neck radiation therapy.
  • Bone marrow or stem cell transplant. Mouth sores are a possible sign of graft-versus-host disease, which is a side-effect of these procedures.

Managing mouth sores

The best way to manage mouth sores is to prevent them or treat them early. Here are some suggestions and options for preventing and treating mouth sores:

  • Suck on ice chips immediately before and during each chemotherapy treatment. This may prevent mucositis caused by certain types of chemotherapy.
  • Your doctor may recommend specific pain-relief strategies if you develop mouth sores. Options include the following:

– A mouthwash solution that contains lidocaine, sometimes called magic mud, magic mouthwash, or triple mix.

– Over-the-counter drugs, such as acetaminophen (Panado). However, it is important to avoid taking aspirin during cancer treatment unless your doctor tells you otherwise.

– Prescription pain medicine.

  • Brush your teeth gently with fluoride toothpaste several times a day. If the mouth sores are severe, use a toothette instead of a toothbrush. A toothette is a sponge on a stick. Floss gently with unwaxed floss. It is also wise to take special care of your mouth during cancer treatment. The following suggestions below may help. 
  • Visit an oncologic dentist before starting treatment if you will be receiving radiation therapy to the head and neck. An oncologic dentist is experienced in treating people with head and neck cancer.
  • Lessen the time that you wear your dentures. Avoid wearing them at night, and consider removing them between meals to help reduce mouth irritation.
  • Choose foods that require little or no chewing.
  • Avoid acidic, spicy, salty, coarse, and dry foods.

If you feel your chemo, radiation, or other cancer treatments have resulted in bad mouth sores or other oral issues, talk with your healthcare professional about your specific medical condition and treatments.


  • American Cancer Society. Accessed January 6, 2016.
  • American Society of Clinical Oncology (ASCO). Mouth Sores or Mucositis. Accessed January 6, 2016.
  • Aziz L, Ebenfelt A. Mucosal secretion changes during radiotherapy in the oral cavity. Clin Oral Investig. 2007 Sep;11(3):293-6. Epub 2007 May 24. 
  • Mayo Clinic. Accessed January 5, 2016.
  • National Cancer Institute. Accessed January 5, 2016.
  • Natural Standard: The Authority on Integrative Medicine. Copyright 2011. Accessed January 5, 2016.

Written by Elsje Smit.