Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at November 19, 2016

Mucositis (also known as oral mucositis, esophagitis, or simply mouth sores) is a painful and occasionally debilitating condition that most commonly affects the mouth, but can also occur in the lining of the gastrointestinal tract. Mucositis develops when the mucous lining becomes inflamed or ulcerated and is characterized by shiny red sores


Definition & Facts

Mucositis can develop anywhere in the gastrointestinal tract; oral mucositis affects the mouth, tongue, and gums. The painful sores and inflammation associated with mucositis can cause difficulty eating, difficulty swallowing (dysphagia), and even difficulty talking.  Doctors have identified five distinct phases of mucositis as it develops, worsens, then heals.

  • Initiation
  • Message generation
  • Amplification and signaling
  • Ulceration
  • Healing

Mucositis is one of the most common side effects of chemotherapy and radiotherapy. However, the individual likelihood of a cancer patient developing oral mucositis depends both on various health factors as well as the type of treatment they receive; the severity of the condition is also determined by these factors. 

Mucositis is especially dangerous for patients with neutropenia (a type of white blood cell deficiency). The combination of these conditions increases their risk of developing septicemia (a toxic illness in which the bloodstream is invaded by bacteria).

Symptoms & Complaints

The most common symptoms of oral mucositis are:

Other complications related to mucositis include:

In chemotherapy patients, signs of mucositis usually develop within the first week of treatment, peaking around the tenth day. Typically these symptoms improve within two to four weeks. 

For patients receiving radiotherapy treatment, mucositis symptoms usually appear during the second week, and last between six and eight weeks.


Cancer treatments cause a breakdown in the epithelial tissue cells that line the gastrointestinal tract. This breakdown leaves tissue vulnerable to infection. The mouth's lining (oral mucosa), is especially sensitive to radiation and chemotherapy; as such, the mouth is the area most commonly affected by mucositis. 

Chemotherapy and radiation treatment cause musocitis in different ways. For patients undergoing chemotherapy, mucositis develops because of a deficiency of white blood cells. Radiation, however, creates an inflammatory, necrotic effect in the mouth's mucous membranes (oral mucosa). This is why mucositis is often more severe and longer-lasting among radiotherapy patients. 

Regardless of the treatment, the initial phase of mucositis occurs when there is damage done to cell DNA. Next, the ulceration phase begins when cell transcription factors cause the body to produce more inflammatory cytokines (small proteins necessary for cell signaling). The healing phase takes place when epithelial cells (tissue that lines the organs and blood vessels) are attracted to the ulceration sites and begin to cover the sores.

Diagnosis & Tests

Oral mucositis is generally diagnosed by visual examination. The presence of ulcers and red sores following radiotherapy or chemotherapy is sufficient evidence for a doctor to diagnose this condition. The most common tests to assess the severity of mucositis are:

  • National Cancer Institute (NCI) Common Toxicity Criteria for Oral Mucositis. The NCI test provides two separate scores, assessing the appearance and severity of ulceration, as well as the patients ability to eat and drink.
  • World Health Organization's Oral Toxicity Score. The WHO test assesses these same elements, but combines the scores into a single number ranging from zero (no presence of mucositis) to four (severe mucositis, rendering the patient unable to eat or drink and therefore in need of supplementary nutrients).
  • Oral Mucositis Assessment Scale. The OMAS is a test that measures the extent of oral ulceration as well as the visual appearance of the sores. It is thought to be a more objective and reproducible test.

Treatment & Therapy

Mucositis treatment is somewhat limited; generally, mouth sores need to heal by themselves. Because of this, most treatments are supportive in nature. Patients are encouraged to perform proper oral care to expedite the healing process. 

For patients with severe oral pain, many oncologists prescribe a medicated rinse or a pain medication to temporarily numb the mouth. Lack of food and fluid intake can lead to dangerous weight loss. In these cases, patients are often referred to nutritionists to secure supplemental nutrition options. In severe cases, oncologists may be forced to delay any further therapy until the ulceration and sores have healed. 

Prevention & Prophylaxis

While it's difficult and, depending on a patient's type of cancer and treatment, unlikely to prevent mucositis entirely, certain measures can greatly alleviate the severity of its symptoms. Some of these include:

  • Finding a dentist who specializes in treating cancer patients; any necessary dental work should be performed over a month before chemotherapy or radiation begins
  • Following an intensive oral care regimen to prevent the risk of infection through mucositis sores
  • Avoiding potential irritants like alcohol, citrus, and spicy foods
  • Quitting smoking or oral tobacco use
  • Increasing the intake of liquids and high-protein foods
  • Avoiding toothpastes with whitening agents