Sore mouth

Oral mucositis (sore mouth) is a side effect of some treatments for lymphoma. This page gives general advice to help you manage the symptoms of oral mucositis.

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What is oral mucositis (sore mouth)?
Treatments that can cause it
Reducing the risk of sore mouth
Treating sore mouth
How can I help myself if I have sore mouth?

What is oral mucositis (sore mouth)?

Oral mucositis happens when the mucous membrane (soft tissue that lines the inside of your mouth) becomes inflamed (swollen, red and painful). This can cause symptoms such as pain when swallowing or mouth ulcers (sores).

Sore mouth usually resolves once you finish your treatment for lymphoma and your blood counts return to their pre-treatment levels. This is around 2–3 weeks after chemotherapy, and around 6–8 weeks after radiotherapy.

For some people, sore mouth lasts longer. This can happen if, for example, you have prolonged neutropenia (low neutrophils).

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Which treatments for lymphoma can cause sore mouth?

Sore mouth is a common side effect of treatment for lymphoma. Chemotherapy and radiotherapy destroy lymphoma cells, but they also damage the cells in the mucous membrane. Some biological (targeted) therapies can also cause sore mouth, although it is unclear how they do it.

With chemotherapy, sore mouth generally occurs around 7–10 days after you start treatment. For most people, it resolves between day 14 and 21 of treatment.

Sore mouth is more common when treatment is given over a long time, particularly if it is also given at high doses. Having chemotherapy-related oral mucositis once increases your risk of developing it again after your next chemotherapy treatment.

Radiotherapy to the head and neck, particularly at high doses, can also cause sore mouth. It typically occurs between day 12 and 15 after you begin treatment. The risk of sore mouth increases if you have both radiotherapy and chemotherapy.

Sore mouth can also happen after a stem cell transplant. It is caused by both the treatment for lymphoma and the immunosuppressive drugs. It often occurs around a week after you begin treatment.

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How can I reduce my risk of developing sore mouth?

Women, children and people over 50 are more at risk of developing sore mouth. 

Lifestyle choices can also have an impact. You can reduce your risk of developing sore mouth by not smoking or drinking alcohol. It also helps to avoid spicy foods, acidic fruits, garlic, onions and vinegar.

Your medical team might recommend treatments to help prevent sore mouth, particularly if there is a high likelihood of you developing it.

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How is sore mouth treated?

Your medical team might prescribe treatments to help prevent or treat sore mouth. This is particularly likely if you have low neutrophils (neutropenia), which is a common side effect of chemotherapy. Neutropenia weakens your immune system and increases your susceptibility to developing ulcers that bleed.


If you develop an infection in your mouth you may need treatment with antibiotics. Antibiotics are given to prevent sepsis, which can be life-threatening.

Infection can be especially serious if your immune system is weakened (you are ‘immunosuppressed’). You are immunosuppressed if you are:

Seek medical advice straightaway if you have any signs of infection including, but not limited to:

  • fever (temperature above 38°C)
  • shivering
  • chills and sweating
  • feeling generally unwell, confused or disoriented
  • earache, cough, sore throat or mouth that makes eating and drinking difficult
  • redness and swelling around skin sores, injuries to intravenous lines
  • diarrhoea
  • a burning or stinging sensation when passing urine
  • unusual vaginal discharge or itching
  • unusual stiffness of the neck and discomfort around bright lights.

Keep a thermometer handy so that you can easily check your temperature. Call your medical team if your temperature goes above 38°C. Remember that shivering can be a sign of infection even if you do not have a fever. This is more likely if you are taking steroids.

Cryotherapy (ice chips)

Cryotherapy is the name given to ice chips placed in your mouth around 5 minutes before you have chemotherapy treatment. For some people, cryotherapy prevents sore mouth; however, it is not suitable with all types of chemotherapy.


Palifermin is a type of growth factor. It encourages the growth of new cells in the mucous membrane. As well as treating the symptoms of sore mouth, palifermin can help to prevent mouth ulcers. You have palifermin by injection each day for a few days before you begin chemotherapy or radiotherapy.

Low-level laser therapy (LLLT)

Low-level laser therapy (LLLT) uses low energy beams of light directed at the mucous membrane of your mouth to reduce the severity of sore mouth. It can help speed up wound healing as well as reduce pain and inflammation. LLLT needs specialist equipment and is only available in some specialist cancer centres.

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How can I help myself if I have sore mouth?

Having a sore mouth is painful and can affect how you feel in general. Speak to your medical team for tailored advice on how to manage this side effect. Here is some general advice that you might wish to discuss with your doctor.

Diet and nutrition

Having sore mouth can impact negatively on your diet and nutrition. You might find it easier to eat soft foods, such as mashed potato, scrambled eggs or soup. Hot food can cause further irritation to your mouth, so serve these foods cool or warm. It is also advisable to avoid spicy and citrus foods, which can cause irritation.

Oral hygiene

If you have sore mouth, it is important to take steps to prevent infection:

  • Rinse your mouth with water or mouthwash after eating. Keeping your mouth clean reduces your risk of getting infections. Avoid mouthwashes that contain salt or alcohol as these can cause further irritation. If your mouth is painful, your medical team might prescribe a special mouthwash, eg one containing anaesthetic.
  • Clean your teeth twice a day using a soft-bristled brush. You could try using children’s toothpaste, which is milder than regular toothpaste.
  • Visit your dentist before you start treatment for lymphoma – you may not be able to have any dental work done during or soon after treatment because of increased risk of infection.

Flossing can damage an already sensitive mucous membrane, allowing harmful bacteria into the bloodstream. If you regularly floss, take care to do it gently if you decide continue to do it during your lymphoma treatment. If you do not floss regularly already, it is not recommended that you begin while you are having treatment for lymphoma.

Dry mouth

Dry mouth is very common when your mouth is sore. There are simple things you can try to help moisten your mouth.

  • Sip fluids throughout the day.
  • Eat moist foods (eg sauces, mousses or jellies).
  • Ask your medical team about artificial saliva treatments.
  • Chew gum or suck a boiled sweet which triggers saliva production.
  • Rinse your mouth 5–6 times a day with a bland solution. An example is ½ teaspoon of bicarbonate of soda (baking soda) mixed with a cup of water. Your medical team can advise you on suitable solutions.
  • Use a moisturiser to protect your lips from dryness.

Pain relief

Pain is often one of the most distressing symptoms of sore mouth. To help relieve pain, try sucking an ice lolly or an ice cube. Your medical team may also prescribe medications, such as:

  • topical medicines (applied to the inside of your mouth), which form a protective coating over the mucous membrane.
  • analgesics (pain relief medications) eg benzydamine, codeine or opioids.

If you wear dentures, you may find it more comfortable to leave them out while you have oral mucositis. Keep them clean and moist even when you are not wearing them.

Remember: Sore mouth is a common side effect of some treatments for lymphoma. Although it is not always possible to prevent it, your medical team can help to relieve the pain. Take care to minimise your risk of infection and always check with your medical team if you have any questions or concerns. Call your medical team immediately if your notice signs of infection or if you feel unwell.

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Further reading

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