How radiotherapy to the head and neck can affect your mouth

Radiotherapy to the head and neck can cause temporary side effects, including:

  • a sore mouth and throat
  • a dry mouth
  • thick, sticky saliva
  • bad breath
  • problems chewing or swallowing
  • loss of taste
  • a hoarse voice.

Side effects usually develop after about 2 weeks of radiotherapy. They may continue for 7 to 10 days after treatment ends, before slowly improving. Most people notice an improvement in their side effects 6 to 8 weeks after finishing radiotherapy.

Your healthcare team includes specialists who will help you manage side effects. They will give you advice and treatment if needed. Tell them if you have side effects or develop new symptoms.

Sometimes radiotherapy causes side effects that are longer-term or that develop months or years later. The most common are a dry mouth and an increased risk of tooth decay.

Your specialist can explain your risk of long-term or late effects. They will also explain things you can do to help reduce your risk. This will include following a regular mouthcare routine during and after radiotherapy.

Side effects of radiotherapy to the head and neck

Radiotherapy to the head and neck can cause temporary side effects, such as a sore mouth or throat and difficulty swallowing. Side effects can be mild or more severe, depending on the size of the area being treated and the length of your treatment. They are usually more severe if you have radiotherapy combined with chemotherapy.

Side effects usually start to develop after about 2 weeks of radiotherapy. They may continue for 7 to 10 days after treatment ends, before slowly improving. Most people notice an improvement in their side effects 6 to 8 weeks after radiotherapy has finished.

Sometimes radiotherapy can cause long-lasting side effects, or new side effects that develop months or even years later. These are called long-term effects and late effects. The most common late effects are a dry mouth and an increased risk of tooth decay. It is very important to follow a regular mouthcare routine during and after radiotherapy.

Your specialist can tell you whether your treatment may cause any late effects. You will also be told about things you can do to help reduce the risk of having problems.

I finished my radiotherapy in May and couldn’t get anything down my throat until November. It’s a long struggle so don’t give up. I set myself targets of six sips of water a day and often didn’t reach that. The first food I managed was chicken noodle soup with all the noodles strained out.


Who can help

There are several specialists who can give you advice and treatments about side effects. You may meet some of them before you start radiotherapy. Others you may meet during or after treatment. Your team may include the following professionals:

  • Doctors – experts in treating cancers of the head and neck areas.
  • Radiographers – experts in radiotherapy and trained in giving you your treatment, support, advice and information.
  • Dietitian – someone who advises you on how to get all the nutrients your body needs.
  • Speech and language therapist (SLT) – a therapist who specialises in helping with communication and swallowing problems.
  • Dentists and dental hygienists – specialists who check your mouth and dental health and give advice about preventing mouth problems.
  • Clinical nurse specialist – a nurse who gives support and information about any aspect of your illness or treatment.
  • Psychologist or counsellors – someone who can help you cope with any emotional difficulties.

Temporary side effects

Sore mouth and throat (mucositis)

Your mouth and throat are likely to become sore after 2 weeks of treatment. You may develop mouth ulcers. Your doctor will give you painkillers to take regularly. Tell them if your mouth is still sore. You may need stronger painkillers or have an infection in your mouth that needs treatment.

We have more about coping if you have a sore or dry mouth.

Dry mouth

Radiotherapy can affect the salivary glands, so you may not make as much saliva as before. Your mouth and throat may become dry. This can make eating and speaking more difficult.

Sipping water regularly helps reduce the dry feeling, so carry a bottle of water with you. Eating soft, moist foods with gravy and sauces is easier than dry or chewy foods.

You may be prescribed artificial saliva to help your mouth feel more comfortable. It comes in different forms, such as sprays, gels, lozenges and pastilles. You may have to try different types to find one that works for you.

Some people find that using a humidifier in their home helps, as it makes the atmosphere less dry.

Your lips can also feel dry and chapped. You can keep your lips comfortable by using a lip balm regularly. But during radiotherapy, you should avoid products that are coloured, perfumed or flavoured.

After a few months, you may begin to make saliva again, but there may not be as much as before. Sometimes the salivary glands do not recover, which leaves the mouth permanently dry.

We have more information about coping with a dry mouth that you may find helpful.

Thick, sticky saliva (mucus)

Radiotherapy can change the consistency of your saliva. It may become thicker, stringy and sticky, like mucus. The mucus does not flow as well as normal saliva, so it may build up in the mouth and throat.

You may feel the need to spit frequently to get rid of the mucus build-up, so it is a good idea to keep tissues with you. Rinsing your mouth regularly can help. Using a sodium bicarbonate mouthwash every 3 to 4 hours may help clear thick saliva. To make the mouthwash, add 1 tablespoon of sodium bicarbonate to 900ml of cooled, boiled water. Rinse the mouthwash around your mouth and then spit it out. You should make a fresh mouthwash each day.

Alternatively, your specialist nurse can give you advice on the type of mouth rinse that might be best for you.

Sometimes a build-up of mucus can cause coughing, especially at night. Your nurse or doctor may prescribe nebuliser. This is a small machine that changes liquid medicine into a fine mist or spray, to help to loosen the mucus. If your sleep is disturbed by coughing, using a nebuliser before bed may help.

Changes in your saliva may get better within about 8 weeks of radiotherapy ending. But sometimes it continues for several months or longer. If the mucus continues, tell your cancer specialist or nurse. They may be able to prescribe medicines to reduce the amount you make.

Bad breath

Bad breath is usually caused by changes to your saliva and can be reduced by regular mouth care. It may also be caused by an infection in the mouth, which is common during radiotherapy treatment. If you have an infection, it can be treated with antibiotic or antifungal medicine.

Problems chewing or swallowing

Radiotherapy to the head or neck area can cause pain and swelling in the mouth or throat. This can make it painful to chew or swallow. An infection in your mouth or throat can also make chewing and swallowing uncomfortable.

Let your doctor or dietitian know if you are having any problems. If drinking makes you cough, tell your doctor or specialist nurse as soon as possible. A speech and language therapist (SLT) can give you advice about swallowing problems.

We have more about coping if you have problems chewing or swallowing.

Loss of taste

Radiotherapy to your head and neck affects your sense of taste. Some people lose their sense of taste completely or find that everything tastes the same (usually quite metallic or salty). Although your sense of taste should recover, it may take many months for this to happen.

We have more advice on coping with taste changes and other eating problems.

A hoarse voice

You may notice your voice becomes hoarse during treatment. If this happens, do not strain it. Try to rest your voice and avoid smoky atmospheres. A speech and language therapist (SLT) can give you more advice on what to do if your voice becomes hoarse. Your voice usually recovers after a few weeks.

Possible late (long-term) effects of radiotherapy

Modern ways of planning and giving radiotherapy are designed to limit the chances of late side effects as much as possible. But some people do have long-term effects after radiotherapy to the head and neck.

Many treatment side effects get better over time. If you have side effects that are not getting better or if you develop new symptoms, let your cancer specialist know. They will assess your symptoms and explain if they are likely to be a result of treatment. You may have tests to find out the cause.

Not everyone will have a long-term effect of treatment. If you are concerned about the risk of developing particular side effects, speak to your cancer doctor or specialist nurse.

The most common late effects include:

  • a dry mouth
  • difficulty swallowing
  • taste changes
  • a higher risk of tooth decay
  • stiffness in the jaw, neck or shoulders
  • changes to your hearing
  • changes in how you look.

We have more information about managing the late effects of head and neck treatment.

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