Side effects of radiotherapy for salivary gland cancer

Most people have some side effects from radiotherapy to the salivary gland area. They come on gradually during the course of treatment and are usually at their worst at the end of treatment. 

The side effects slowly get better over the 4 to 6 weeks following treatment. But it can take quite a few months to completely get over a long course of treatment.

Everyone is different and the side effects vary from person to person. You may not have all of the effects mentioned.

Skin problems in the treatment area

Your skin might go red or darker in the treatment area. You might also get slight redness or darkening on the other side of your body. This is where the radiotherapy beams leave the body. 

The red or darker areas can feel sore. This may start after your radiotherapy treatment is completed. Your radiographers may give you creams to soothe your skin. The soreness usually goes away within 2 to 4 weeks of ending the treatment. But your skin might always be slightly darker in that area.

Tell the radiotherapy staff if you notice any skin changes.

Tiredness and weakness

You might feel tired during your treatment. It tends to get worse as the treatment goes on. You might also feel weak and lack energy. Rest when you need to.

Tiredness can carry on for some weeks after the treatment has ended. But it usually improves gradually.

Various things can help you to reduce tiredness and cope with it, such as exercise. Some research has shown that taking gentle exercise can give you more energy. It's important to balance exercise with resting.

Dry mouth

Radiotherapy to the salivary glands can reduce the amount and quality of saliva produced. Usually, only the glands on the treated side of your face are affected. This means that glands on the other side should still make saliva.

Having a dry mouth can be uncomfortable. Various things can help.

  • Try to drink at least 3 pints (one and a half litres) of fluid a day
  • Choose meals that are moist.
  • Use gravies and sauces to make swallowing easier.
  • Take regular sips of water with your meal to help you chew and swallow your food.
  • Suck small amounts of ice chips to refresh your mouth.
  • Chew sugar free chewing gum.
  • Try eating fresh pineapple.
  • Get your doctor or nurse to give you medicines to stimulate your salivary glands.
  • Ask your doctor or pharmacist about artificial saliva products, such as tablets, mouthwashes, gum, pastilles, and toothpaste.
  • It is very important to have regular check ups with your dentist.
Most people start making saliva again within 4 to 8 weeks of finishing treatment. The saliva is likely to be quite thick and may taste unpleasant at first.

Rarely, some people have a permanently dry mouth after the treatment. This can make eating and talking uncomfortable.

Sore mouth and throat

Your mouth and throat may get increasingly sore with mouth ulcers as you go through your treatment. You may need strong painkillers such as morphine. 

Your doctor may also prescribe a mouth gel such as Gelclair. This gel forms a protective barrier on the inside of the mouth, a bit like a dressing. This can make your mouth less painful. You will then find it easier to eat and drink.

Taste changes

Radiotherapy to the head or neck often affects taste. You may lose your sense of taste, have strange tastes or a dull taste. Some people describe a metallic taste in their mouth after radiotherapy.

Loss of taste can reduce your appetite. This doesn’t help when you are finding it difficult to eat anyway. Although you can recover your sense of taste, some people may find it is permanently changed.

Problems with your teeth

Radiotherapy to your mouth can make you more likely to get tooth decay. You need to go for check ups at the dentist more often. Fluoride treatment may help to protect your teeth. You can have this as a mouthwash to use twice a day.

You might need to have some teeth taken out before you start treatment. Your doctor may refer you to a restorative dentistry consultant before your radiotherapy. A restorative dentist is a specialist in replacing lost tissues and teeth. 

Remember to tell your dentist that you have had radiotherapy to your salivary glands 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.

Swelling (lymphoedema)

After radiotherapy to treat a head and neck cancer, you are at risk of getting swelling called lymphoedema in your neck or face. Lymphoedema is pronounced lim-fo-dee-ma.

Lymph fluid is in all body tissues. It comes from the tiny blood vessels into the body tissues. Usually, it drains back into the bloodstream through channels called lymph vessels. These are part of the lymphatic system.

A build up of lymph fluid in an area of the body can happen if lymph drainage channels or lymph nodes are blocked, removed, or damaged.

Lymphoedema in the head or neck can also cause symptoms inside your mouth and throat. For example, swelling of your tongue and other parts of your mouth.

Tell your doctor or nurse straight away if you:

  • have any swelling in the head or neck area or a feeling of fullness or pressure
  • find it difficult to swallow
  • have changes in your voice

Lymphoedema is easier to control if treated early. It's important that you are referred to a lymphoedema specialist if you have signs of swelling. This is usually a nurse or physiotherapist.

Difficulty swallowing

During and after treatment, you might have difficulty swallowing.

You may see a speech and language therapist (SLT) before you start treatment if this is likely to affect your swallowing. An SLT can assess your swallowing during and after treatment. They can teach exercises to support you with swallowing difficulties. And they work with a dietitian if you are finding it difficult to eat.

You can have feeds through a nasogastric tube that goes up your nose and down into your stomach. Or you can have a PEG tube (percutaneous endoscopic gastrostomy tube) that goes through the skin into your stomach. Your nurse or dietitian will tell you more about this if you need to have one. They will also show you and your relatives how to give the feeds. 

You might find that having a soft diet is easier to swallow until a few weeks after your treatment is over. Foods such as soups and stews are easier to swallow than more solid foods like meat or toast.

Your radiotherapy department can give you an information sheet to help advise you.

Tell your doctor or radiographers if you have problems swallowing. They can advise you on ways to reduce this.

Tips for eating and drinking

  • Drink about 3 litres of water a day while having treatment.
  • Eat soft foods.
  • Eat slowly and avoid eating late in the day.
  • Drink plenty during and after meals to soften your food.
  • Eat small amounts often rather than big meals.
  • Try different foods to find out which are easiest to swallow.
  • You can have high calorie drinks to boost your calorie intake if you need them.
  • You might need to have liquid food into your vein or through a tube into your nose or stomach if you can’t eat enough.

Hair loss in the treatment area

Radiotherapy causes some hair loss to the area of treatment. It can also cause hair loss on the opposite side of the head. This is where the radiotherapy beam leaves the body (the exit site). 

Most of the hair loss can recover unless the full radiation dose needs to be given to the underlying skin.

Feeling or being sick

You might feel sick at times. You can have anti sickness medicines. Let your treatment team know if you still feel sick, as they can give you another type.   

Damage to the jawbone

Radiotherapy can sometimes damage the jawbone and break down the bone. This is because radiotherapy can reduce the blood supply to the bone. This is called osteoradionecrosis. This is rare but it can happen months or years after your treatment has finished. Symptoms include pain and swelling in your gums.

Before your radiotherapy, you usually see a specialist dentist. They can remove damaged or broken teeth and make sure your dentures fit properly. 

They will also show you how to keep your mouth and teeth clean. You will need to do this during your radiotherapy and for a few months afterward, or sometimes longer. 

Difficulty opening your mouth

Radiotherapy can damage the nerve that controls the muscles that move our mouth. This problem is called trismus. Your doctor or nurse will give you exercises to help strengthen your muscles.

Hearing loss

Radiotherapy to the parotid gland area can sometimes damage the nerves that help you hear. You might have your hearing tested before and after treatment to check for any signs of hearing loss. 

Watch our video on the general side effects of radiotherapy. It lasts for around 8 minutes. 

Long term side effects

Most side effects gradually go away in the weeks or months after treatment. But some side effects can continue or might start some months or years later.

  • Principles and practice of oncology (12th edition)
    V DeVita, T Lawrence and S Rosenberg
    Wolters Kluwer, 2023

  • Salivary gland cancer: ESMO-European Reference Network on Rare Adult Solid Cancers (EURACAN) Clinical Practice Guideline for diagnosis, treatment and follow-up
    C van Herpen and others
    Practice Guideline ESMO Open, 2022. Vol 7, Issue 6

  • Management of Salivary Gland Tumours: United Kingdom National Multidisciplinary Guidelines
    S Sood and others
    The Journal of Laryngology & Otology, 2016. Vol 130, Supplement S2

  • Lymphedema Outcomes in Patients with Head and Neck Cancer
    B Smith and others
    Otolaryngology Head and Neck Surgery, 2015. Vol 152, Issue 2

  • External Beam Therapy
    Peter Hoskin
    Oxford University Press, 2012

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. Please contact patientinformation@cancer.org.uk with details of the particular issue you are interested in if you need additional references for this information.

Last reviewed: 
26 Apr 2023
Next review due: 
26 Apr 2026

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