The symptoms of mucositis depend on whether your mouth or digestive system is affected.

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.

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.