Mucositis is a condition characterised by pain and inflammation of the body's mucous membrane.

The mucous membrane is the soft layer of tissue lining the digestive system from the mouth to the anus.

Mucositis is a relatively common side effect of chemotherapy. It's also sometimes caused by radiotherapy, especially if it involves the head or neck.

It's often divided into two main types, including:

  • oral mucositis – which can cause mouth ulcers (sores) and pain or difficulty swallowing
  • gastrointestinal mucositis – which occurs inside the digestive system and often causes diarrhoea

It's also possible for mucositis to affect the lining of the anus – a condition known as proctitis.

What are the symptoms or oral mucositis?

The symptoms of oral mucositis usually begin five to 10 days after starting chemotherapy, or 14 days after starting radiotherapy.

The tissue inside your mouth will start to feel sore, as if you have been burnt by eating hot food. It's also likely you will develop white patches or ulcers on the lining of your mouth and, in some cases, on your tongue and around your lips.

These ulcers may become very painful and may make it difficult for you to eat, drink or talk. You may also have a dry mouth and a reduced sense of taste. These changes in your mouth can make it more difficult to speak. Relatives and friends may notice your breath smells bad (halitosis).

Milder symptoms of oral mucositis should ease three to four weeks after your course of chemotherapy or radiotherapy has finished. More severe cases will usually require hospital treatment for monitoring and nutritional support.

What are the symptoms of gastrointestinal mucositis?

The symptoms of gastrointestinal mucositis are more common in people receiving chemotherapy, although they may also occur if you've had radiotherapy to treat cancer in your abdominal (tummy) or pelvic area.

The symptoms of gastrointestinal mucositis usually begin 14 days after you start your chemotherapy or radiotherapy. They can include:

  • diarrhoea
  • ulcers in your anus and rectum
  • rectal bleeding, which can cause blood in your stools
  • passing mucus from your anus (back passage)
  • abdominal pain
  • difficulty swallowing (dysphagia)
  • nausea (feeling sick)
  • bloating

Most of these symptoms will stop a few weeks after your treatment has finished, although occasionally the symptoms of diarrhoea can persist for several months after radiotherapy has finished.

Why does mucositis happen?

The digestive tract is more prone to the harmful effects of chemotherapy or radiotherapy, which can damage the delicate lining.

If you're undergoing cancer treatment that could potentially cause mucositis, you'll be checked regularly for the condition. Mucositis can usually be diagnosed after an examination or a description of your symptoms.

Read more about the causes of mucositis and diagnosing mucositis.

Who is affected?

It's estimated that around 40% of people receiving chemotherapy as part of their cancer treatment will develop some degree of mucositis. It can be more severe in some people, depending on the treatment used.

Mucositis is more common among certain types of cancer. For example, it's estimated that up to 97% of people who have radiotherapy for head or neck cancer will develop some form of mucositis.

About 70% of people receiving high doses of chemotherapy because they are undergoing a stem cell transplant (bone marrow transplant) will develop mucositis.

How is mucositis treated?

The main aim of treatment for oral mucositis is to prevent infection and reduce any pain. This is done by using painkillers and practising good oral hygiene.

Treatments are also available to reduce the symptoms of oral mucositis, such as low-level laser therapy (LLLT) and a medication called palifermin.

Treatment for gastrointestinal mucositis aims to reduce the main symptoms of the condition, such as diarrhoea and inflammation. Treatment includes a combination of medicines and self-care measures.

The symptoms of mucositis should begin to improve a few weeks after chemotherapy or radiotherapy has finished, although it can sometimes take longer.

Read more about treating mucositis.


The most serious cases of mucositis can lead to a number of associated health complications.

Many people with mucositis find it painful to swallow food and require alternative feeding methods, such as a feeding tube.

Also, mouth ulcers can become infected with bacteria. The infection can spread to the blood, then on to other organs. This is known as sepsis and can be life-threatening.

Can mucositis be prevented?

It's not always possible to prevent mucositis, but some treatments can be taken during radiotherapy or chemotherapy to try to reduce the severity of mucositis or how long it lasts. 

Treatments include medications such as palifermin, benzydamine, sulfasalazine and amifostine.

Read more about preventing mucositis.

Page last reviewed: 19/12/2014

Next review due: 19/12/2017