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Side effects of radiotherapy

Side effects tend to start a few days after you start radiotherapy. They gradually get worse over the days and weeks of your treatment. They can continue to get worse after your treatment ends. But they usually start to get better after 2 or 3 weeks.

Getting over a long course of treatment completely can take quite a few months. If you had chemotherapy at the same time as radiotherapy, it can take 3 to 4 months for the side effects to settle. 

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.

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. Your radiographers will 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.

Your throat might get sore. It may be painful to swallow drinks or food.

You can have painkillers to reduce the soreness and you may need strong painkillers, such as morphine as go through the treatment. Take them half an hour before meals to make eating easier.

Tell your doctor or nurse if your throat is sore.

During and after treatment, you might have a feeling of a lump in the throat when you swallow. This can make it difficult to swallow solid foods.

This problem is often at its worst about 10 days to 2 weeks after you finish treatment.

Ask to see a dietitian if you have problems with eating and drinking
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 through a tube into your nose or stomach if you can’t eat enough. This is called tube feeding.

Your mouth might get very dry, which can be uncomfortable. Various things can help.

Tips

  • 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 about artificial saliva products, such as tablets, mouthwashes, gum, pastilles, and toothpaste.
  • It is very important to have regular check ups with your dentist.

Your voice might become hoarse as you go through your radiotherapy. Depending on the area being treated your voice may disappear altogether. It will come back, but may sound different afterwards. 

After radiotherapy to treat a head and neck cancer, you are at risk of getting swelling called lymphoedema in your neck or face.

Lymphoedema in the head or neck area might also cause swelling of your tongue and other parts of your mouth.

Tell your doctor 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

Side effects if you have chemotherapy with radiotherapy

Chemotherapy combined with radiotherapy can make some side effects worse. Combining these treatments is called chemoradiotherapy.

Last reviewed: 
13 Jul 2018
  • National Radiotherapy Implementation Group Report - Image Guided Radiotherapy (IGRT) guidance for implementation and use

    National Cancer Action Team, August 2012

  • Radiotherapy Services in England 2012

    Department of Health Cancer Policy Team, November 2012

  • Advances in radiotherapy

    S Ahmed and others. British Medical Journal, 2012. Vol. 345

  • Lymphedema Outcomes in Patients with Head and Neck Cancer
    B Smith and others
    Otolaryngology Head and Neck Surgery. 2015 February; 152(2): 284–291.

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