Side effects of radiotherapy for head and neck cancer

Radiotherapy for head and neck cancer can cause side effects. These usually improve a few weeks after treatment is over.

About side effects of radiotherapy

Radiotherapy to the head and neck causes temporary (or acute) side effects. 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 begin after about 2 weeks of radiotherapy. They continue to develop for up to 2 weeks after treatment ends, before slowly improving. Most people notice an improvement 6 to 8 weeks after radiotherapy has finished.

Radiotherapy for head and neck cancer can also cause late effects. These are side effects that do not go away, or that develop months or years after treatment.

What you can do to manage side effects

Following the advice your team gives you will help to reduce side effects and improve your recovery. This includes advice about preparing for treatment. For example, the advice may include:

  • not smoking
  • avoiding alcohol, especially spirits
  • eating as well as you can to keep to a healthy weight
  • drinking plenty of fluids
  • doing exercises to prevent jaw or shoulder stiffness, or to help with swallowing
  • trying to keep as active as you can.

Tell your nurse, radiographer or doctor about your side effects. There are things they can do to improve your side effects. They can also tell you things you can do yourself.

Managing side effects during radiotherapy

Your doctor can tell you about any possible late effects and what you can do to help reduce the risk of these.

Sore and sensitive skin

The skin on your face and neck will slowly redden or darken and may feel sore and itchy. This usually starts after about 2 weeks of treatment. The skin may get dry and start to peel. Or the area may become moist. You may be given non-stick dressings to cover the area.

The radiotherapy team will give you advice on how to look after your skin. They can prescribe creams, dressings or painkillers if needed. A skin reaction may be at its worst 2 weeks after treatment, but should start to improve after this.

Tips for looking after your skin

  • Wash your skin gently with soap or aqueous cream and lukewarm water. Gently pat it dry. Only use soaps, creams and lotions that your radiotherapy team recommends.
  • Avoid wet shaving for a time, as your skin will be very delicate.
  • Try to wear loose, cotton clothing, as this is less likely to irritate sore skin. Avoid anything with a stiff or tight collar.

Protecting the skin from the sun

The skin in the treated area will be more sensitive to the sun during and after radiotherapy, especially in the first year. Cover up with a hat and a soft cotton or silk scarf around your neck to protect your skin. Use sun-protection cream with an SPF of at least 30 after any skin reaction has gone.

Sore mouth and throat

Your mouth and throat are likely to become sore after a few weeks. You may develop mouth ulcers or a mouth infection. Your doctor, radiographer, nurse or dentist will tell you what to look for. Keeping your mouth clean can help to prevent an infection.

Your doctor or nurse will prescribe treatment for any infection, and painkillers to take regularly. Towards the end of radiotherapy, your mouth may be very sore and it can be painful to eat. You may need strong painkillers, such as morphine. Your doctor or specialist nurse can discuss this with you.

We have more information about coping with mouth problems.

Your dietitian will see you regularly to make sure you get enough nutrition and calories each day. You may need to be fed through a tube if you cannot eat and are losing lots of weight. This is only until treatment is finished and your swallowing is back to normal. You might get back to eating normally a few weeks after radiotherapy has finished. But it may take longer than this. 

Tips for looking after your mouth and teeth

  • Brush your teeth or dentures with a small, soft toothbrush after each meal using fluoride toothpaste and gel.
  • Rinse your mouth daily with a non-alcohol-based mouthwash, prescribed by your doctor.
  • Use a salt or sodium bicarbonate mouthwash at least 4 times a day. Add 1 teaspoon of salt to 900ml of cooled, boiled water. Your radiotherapy team may have a certain mouthwash they recommend you use as well.

If your dentures are uncomfortable, you may need to leave them out for a few weeks. But speak to the radiotherapy staff first, as this may affect how your radiotherapy mask fits.

Radiotherapy reduces saliva, which helps protect your teeth from decay. After radiotherapy, you are more likely to get tooth decay. It is important to continue looking after your mouth and teeth. 

You should see your dentist every 3 to 6 months and a dental hygienist when your dentist suggests. If problems are found early they are often easier to treat.

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.

Tips for coping with a dry mouth

  • sip water regularly and always carry a bottle of water with you
  • eat soft, moist foods with gravy and sauces instead of dry or chewy foods
  • use artificial saliva which your doctor can prescribe – it is available as sprays, gels, lozenges and pastilles
  • chew sugar-free gum
  • use a humidifier to make the atmosphere in your home less dry
  • use a lip balm for dry lips, but ask your radiographer for advice on which one to use. 

After a few months, you may start 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 coping with a dry mouth.

Thick sticky saliva

Radiotherapy can change the consistency of your saliva. It may become thicker, stringy and sticky, like mucus. It may also build up in the mouth and throat. Tell your nurse or doctor if your mucus is not white or clear (discoloured). This may be caused by an infection.

You may feel the need to spit often 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 may help clear thick saliva. Ask your specialist nurse for advice about the type of mouthwash that is best for you, and how to prepare it.

Sometimes mucus build-up can cause coughing, especially at night. Using a nebuliser regularly, and especially before bed, may help. A nebuliser changes liquid medicine into a fine mist or spray, to help to loosen the mucus. Your nurse or doctor can prescribe a nebuliser and explain how to use it.

Changes in your saliva may improve within about 8 weeks of radiotherapy finishing. But sometimes it continues for several months or longer. Tell your doctor or nurse if this happens. They may be able to prescribe medicines to help.

Bad breath

This is usually caused by changes to your saliva or an infection in the mouth. If you have an infection, it can be treated with antibiotics or antifungal medicine.

Loss of taste

You may lose your sense of taste or find everything tastes the same. The taste is usually quite metallic or salty. Your sense of taste should recover, but 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. Talk in a normal voice and avoid whispering or shouting.

Try to rest your voice and avoid smoky atmospheres. A speech and language therapist (SLT) can give you more advice. Your voice usually recovers after a few weeks.

Feeling sick

Sickness is more likely to affect people who have chemotherapy and radiotherapy together. If it is a problem, your doctor can prescribe anti-sickness medicines (anti-emetics).

We have more information about managing nausea and vomiting.

Tiredness (fatigue)

You are likely to become tired as treatment goes on and may need to take things slowly. Try to pace yourself and save your energy for things that you want to do, or that need doing. Balance rest with keeping active – even going for short walks will help you to feel less tired.

Fatigue can continue for a few months after treatment finishes, but slowly gets better. We have more information about managing fatigue.

Late effects of radiotherapy

If your side effects are not improving, or you develop new symptoms, tell your cancer doctor. They will assess if your symptoms are linked with treatment and may arrange tests.

Late effects may include:

  • a dry mouth
  • higher risk of tooth decay
  • difficulty swallowing
  • stiffness in the jaw, neck or shoulders
  • swelling in the head and neck area called lymphoedema.

We have more information about late effects of head and neck treatment and how to manage them.

About our information

  • References

    Below is a sample of the sources used in our head and neck cancer information. If you would like more information about the sources we use, please contact us at

    Machiels J.-P, Leemans C. R. et al. Squamous cell carcinoma of the oral cavity, larynx, oropharynx and hypopharynx. EHNS- ESMO-ESTRO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology, 2020. Volume 31, Issue 11, Pages 1462-1475.

    National Institute for Health and Care Excellence (NICE). Cancer of the upper aerodigestive tract: assessment and management in people aged 16 and over. NICE guideline NG36 2016 (updated 2018). 

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Dr Chris Alcock, Consultant Clinical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

Date reviewed

Reviewed: 01 March 2022
Next review: 01 March 2025
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

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