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Sore mouth and problems with your teeth

You might have problems with your mouth or teeth, such as tooth decay or thrush during or after radiotherapy to your head and neck. Find out about ways to help with a sore mouth. 

The cells lining your mouth are sensitive to radiation. So radiotherapy is likely to make your mouth sore after a week or so.This is called oral mucositis.

The soreness usually only lasts while you are having treatment and for a few weeks afterwards.

Dry mouth

Your treatment might affect the salivary glands so that they produce less, or no, saliva. It can be uncomfortable to chew or swallow. Let your radiographer or doctor know if you're having problems. 

After the treatment ends it can take some time for saliva production to get back to normal. If the radiotherapy treatment area included the salivary glands, you might have a permanently dry mouth afterwards. If this is the case for you, your doctor will explain this before you start treatment.

Some of the following tips might help:

  • Ask your doctor to prescribe medicines that stimulate saliva.
  • Sip drinks often to keep your mouth moist.
  • Moisten your food with sauces, gravy, cream, custard or ice cream.
  • Chewing sugarless gum can make your salivary glands produce more saliva.
  • Clean your tongue with a liquid made from a teaspoonful of bicarbonate of soda in a litre of warm water.
  • Use lip balm to keep your lips moisturised.
  • Use moistened cotton wool or a soft toothbrush to clean your tongue.
  • Ask your doctor to prescribe artificial saliva sprays or gels.

Mouth ulceration

Sometimes the delicate lining inside your mouth can break down during radiotherapy. This is called ulceration. If it happens, your doctor can give you painkillers to help you cope.

You might need to have a fine feeding tube into your nose if your mouth is very sore, because it will be painful to eat or drink. The tube is called a nasogastric tube.

Or you might have a tube put directly into the stomach through the skin and muscle of the abdomen. The tube is called a percutaneous endoscopic gastrostomy tube (PEG tube).

Thrush infection

Radiotherapy can also make it easier for infections of the mouth to develop, such as thrush. 

Let your doctor or nurse know if you have any white patches on the inside of your mouth or on your tongue. They can prescribe medicines to help.

Your radiotherapy staff will check your mouth regularly during your treatment.

Taste changes

Radiotherapy can also affect your taste buds. You might notice changes in the way your food tastes. Some people say their food has a metallic taste. Others say that all foods taste the same.

There are some tips on making food more tasty. You might need to wait to try these until your mouth has recovered from the treatment and is not sore any more.

You could try using more herbs and spices to flavour your food, as well as using strong tasting sauces like sweet and sour. Sharp tasting foods, such as fresh fruit and sharp boiled sweets can be refreshing but only use these after your mouth has healed.

The radiotherapy staff can arrange for you to talk to a hospital dietitian for advice about overcoming taste changes.

Problems with your teeth

Before you start radiotherapy to the head and neck you visit a dentist. They look for any teeth that might be decaying or already decayed and will remove them. This is because radiotherapy makes it more likely that your teeth will decay so it's best to take them out at first to avoid problems. Your mouth will also not heal as quickly after radiotherapy.

You'll also need to go for check ups at the dentist more often. Fluoride treatment might help to protect your teeth. You can have this as a mouthwash to use twice a day. 

Remember to tell your dentist that you have had radiotherapy to your mouth before you have any dental work. Your dentist might need to change the way they treat you. They may also need to talk to your radiotherapy doctor before giving you any treatment.

Things you can do to help

There are some things you can to stop any further irritation to your mouth. These include: 

Eating and drinking

Some foods and drinks can irritate your mouth and might be painful to eat. These include: 

  • spicy foods
  • alcohol - especially spirits
  • dry foods, such as crisps might scratch your mouth
  • very hot food or drinks

Because of this it can be best to eat a bland diet for a while. And soft foods such as potato and porridge.

Mouth care

A dry, sore mouth is more prone to infection. So your doctor or nurse might give you mouthwashes and a mouth care routine to follow. This helps keep your mouth healthy during your treatment. 

It is important to keep your mouth clean and as healthy as possible. It's best to use a small soft toothbrush to clean your teeth. And you might need to clean them more than twice a day.


Smoking might make the soreness worse. You can try to cut down on smoking. Talking to the radiotherapy staff about nicotine replacement treatments can help with this. 


If you wear dentures they may make your mouth more sore during radiotherapy treatment. You might find it more comfortable to take them out for some periods during the day.

Information and help

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