Radiotherapy tiredness | Cancer Research UK
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Radiotherapy tiredness

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This page tells you about tiredness caused by radiotherapy. There is information about


Why you may feel tired

You might feel very tired during your radiotherapy treatment. This is because the body has to repair damage caused by the radiotherapy to healthy cells. 

It is important to drink about 3 litres of water a day if possible while having treatment. Hydration helps the body to repair the radiotherapy damage better. If you have to travel to your treatment each day, you may get even more tired. 

Tiredness tends to creep up on you as you go through your treatment. So you may not feel tired at the beginning of your course but you are very likely to by the end. You may feel like having a sleep 1 to 2 hours after each radiotherapy treatment. This tiredness is called fatigue and you may also feel weak and as though you have no energy.

Tiredness can still be a problem for some months after your treatment has finished.


Tips for boosting or saving energy

There are many things that you can do in your everyday life that help you use up less energy. Taking short cuts on some things or getting help from other people can help you feel less tired. 

Some research into treating fatigue shows that it is important to balance exercise with resting. Try to schedule in a short walk each day. You might find that you can gradually increase the distance. Pick the time of day when you are feeling least tired. Remember though, that however far you walk, you'll have to walk the same distance back, so try not to overdo it.

Try some of the following to help save your energy

  • Try not to rush
  • Plan ahead where possible
  • Give yourself plenty of time to get to places
  • Put chairs around the house so you can stop and rest if necessary
  • Sit down to dry off after a bath or put on a towelling dressing gown and let that do the work
  • Get an occupational therapist or social worker to get hand rails put up in your bathroom to hold on to when getting in or out of the bath or shower
  • Sit down to put most of your clothes on
  • When dressing, try not to bend down too much – bring your foot up on to your knee to put socks and shoes on
  • When dressing, fasten your bra at the front first and then turn it to the back
  • Wear loose fitting clothes
  • Wear clothes with few buttons to do up
  • Where possible do household tasks sitting down
  • Choose clothes that don't need ironing
  • Write a list of shopping and go when the supermarket is not busy or have food delivered
  • If you have children, play games that you can do sitting or lying down, such as board games, reading books and drawing pictures
  • Ask family and friends for help with things like shopping, housework, gardening, and collecting the children from school
  • You may find it easier to have lots of small meals, rather than the usual 3 meals a day
  • Have plenty of nutritious snacks and drinks in stock that you can have whenever you feel like eating
  • Don't forget to do things that you enjoy – this may take your mind off things a bit and make you feel more relaxed
  • Buy ready made meals that you can quickly heat up rather than making food from scratch

Tiredness after brain radiotherapy

People having radiotherapy for brain tumours can be particularly affected by tiredness and it can be worse if you are also taking steroids. The tiredness often reaches its maximum 1 to 2 weeks after the end of treatment. 

A small number of people are asleep virtually all day for a short time after a long course of radiotherapy to the brain. You may hear this called somnolence syndrome.


More information about radiotherapy

Find out about

External beam radiotherapy

Internal radiotherapy

Side effects of radiotherapy

Tiredness and cancer


For general information and support

Contact the Cancer Research UK nurses on freephone 0808 800 4040 (Open 9am to 5pm, Monday to Friday)

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Updated: 14 March 2016