Radiotherapy side effects
You might have radiotherapy for a cancer that started in the brain. This is a primary brain tumour. Or you might have radiotherapy for a secondary brain cancer. This means a cancer that has spread to the brain from another part of the body.
The main side effects of radiotherapy to the brain include:
tiredness
sickness
worsening of symptoms
You may also experience more general side effects of radiotherapy such as hair loss and sore skin.
Read more about the general side effects of radiotherapy
Like all side effects of radiotherapy, you might not feel these straight away. Side effects tend to come on gradually as you go through your treatment. And for a few weeks afterwards. Everyone reacts differently to radiotherapy, so how you feel varies from person to person.
Radiotherapy can cause tiredness. There are different reasons for this. The body uses up energy reserves to repair healthy cells damaged by the radiotherapy. If you have taken as part of your treatment, you might also find that you feel extremely tired when you stop taking them. Travelling to the hospital each day for treatment can also make you tired.
You might feel weak and lack energy as well as being tired. Various things can help you to reduce tiredness and cope with it. This includes exercise. This can give you more energy but you need to balance it with resting.
Get tips on coping with tiredness
In a few people, the tiredness can become very severe a few weeks after treatment has finished. You may also feel drowsy and irritable. This is a rare side effect and is called hypersomnia or somnolence syndrome.
It is extreme tiredness that can make you feel very drowsy and want to sleep a lot. You might also have:
headaches
a high temperature
loss of appetite
feeling and being sick (nausea and vomiting)
If you are sleeping a lot or have these symptoms and are worried, contact the team looking after you. It usually gets better on its own over a few weeks.
Radiotherapy to the brain can make you feel or be sick. This is called nausea and vomiting. The sickness might last for a few weeks after the treatment has finished. Medicines, diet and sometimes complementary therapies can help to control sickness.
Sickness can usually be well controlled with medicines. Your radiotherapy team can give you anti sickness tablets. Some people find that it helps to take an anti sickness tablet about 20 to 60 minutes before having radiotherapy.
Other people find they manage better by taking anti sickness tablets regularly throughout the day during their course of treatment. You can discuss which would be best for you with your radiotherapy team.
Your doctor might give you steroids to take while having brain radiotherapy. Radiotherapy to the brain can cause swelling which can lead to nausea. Steroids can help to relieve the pressure.
Find out more about how to control sickness, including complementary therapies and diet tips
Radiotherapy to the brain causes short term swelling in the treatment area. This raises the pressure in the brain.
Doctors call this oedema. It can make your symptoms worse for a time. This can be frightening because you might think the radiotherapy isn't working. Raised pressure in the brain might cause:
headaches
feeling sick
fits (seizures)
The swelling from radiotherapy goes down after treatment. While you have the treatment your doctor gives you medicines to take.
Steroids can reduce the swelling in the brain. Your doctor will tell you how long to take the steroids for. Usually, you gradually lower the dose of steroids after the treatment ends. But if the swelling hasn't gone down enough, your symptoms might come back.
It is important to talk to your radiotherapy team if you think your symptoms are getting worse. They will be able to reassure you and might increase your dose of steroid tablets until your symptoms gets better.
Find out more about steroid treatment for brain tumours
You might have a targeted cancer drug called bevacizumab (Avastin) if you can't take steroids for any reason. Bevacizumab can lower raised pressure in the brain. It does this by changing the growth of blood vessels around the tumour.
This video shows people affected by cancer talking about the side effects of radiotherapy for brain cancer. The video is around 5 and a half minutes long.
You may feel anxious about radiotherapy side effects and this is normal. It can help to talk through any worries you have with your doctor, nurse or radiographer.
Last reviewed: 05 Feb 2024
Next review due: 05 Feb 2024
Primary brain tumours are tumours that start in the brain. They can start anywhere in the brain and there are many different types of tumour.
Radiotherapy can cause a range of side effects, including tiredness and sore skin in the treatment area. Find out more about the general side effects of radiotherapy.
Cancer and its treatment can cause extreme tiredness known as fatigue. There are ways this can be treated.
There are different reasons why you could feel sick. This includes the cancer itself or its treatment. There is information about how this can be managed and treated.
A complementary therapy means you can use it alongside your conventional medical treatment. It may help you to feel better and cope better with your cancer and treatment. An alternative therapy is generally used instead of conventional medical treatment.
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