Side effects of radiotherapy

Radiotherapy for a brain tumour may cause side effects. These usually disappear gradually after treatment. Common side effects include:

  • Tiredness (fatigue) – having radiotherapy and travelling to hospital everyday can make you tired. Make sure you balance rest and activity. Some people get extreme tiredness four to eight weeks after treatment. This usually gradually gets better over a few weeks.
  • Headaches – let your doctor know if you get headaches. They can prescribe pain-killers or steroids.
  • Hair loss – you will lose your hair in the treated area. This usually grows back after treatment.
  • Skin irritation – radiotherapy may make your skin red, itchy or sore. Your nurse or radiographer will tell you how to look after your skin.
  • Feeling sick - your doctor can give you anti-sickness drugs to help.

Sometimes radiotherapy causes side effects that only develop months or years after treatment. Possible late side effects include:

  • changes to memory, thinking and reasoning
  • developing a cataract
  • changes in hormones levels
  • developing a second cancer (this is rare).

Always let your doctor or nurse know about any side effects during or after treatment. They can give you advice and treatment to help.

Side effects during radiotherapy

You may develop side effects during radiotherapy for a brain tumour. These usually improve over a few weeks or months after treatment. Your doctor, nurse or radiographer will let you know what to expect.

Some people find the side effects get worse for a short time after their treatment has finished. You may feel low or worry your treatment isn’t working. But it is usually a reaction to the radiotherapy or it may be because your steroids have been reduced or stopped.

Let your doctor or nurse know straight away if your side effects get worse during or after treatment. They can give you advice on how to manage them.

Tiredness (fatigue)

Radiotherapy can make you tired so try to get as much rest as you can, especially if you have to travel a long way for treatment each day. Tiredness can continue for several months after treatment has finished. Balancing rest and activity throughout the day is important as your body needs rest to recover from the treatment.

Some people get extreme tiredness after radiotherapy to the brain. This can happen about four to eight weeks after treatment. You may have very little energy, feel drowsy and spend a lot of time sleeping. It gradually gets better over a few weeks.


Some people have headaches during radiotherapy. Let your doctor know if this happens. They can prescribe painkillers to control these. Radiotherapy can cause swelling and increased pressure. If your headache is caused by this, your doctor will prescribe steroids to treat it.

Hair loss

You will lose the hair in the area being treated and there may be some hair loss on the opposite side of your head where the radiation beams exit. Your hair will usually grow back within two to three months of finishing treatment. Sometimes it grows back a slightly different colour or is thinner than before.

We have more information about coping with hair loss.

Skin irritation

Your skin in the treated area may get red, dry, itchy and feel sensitive or sore. Dark skin may get darker. Your nurse or radiographer will give you advice on looking after your skin. If it becomes sore and flaky, let them know. Your doctor can prescribe creams to help.

Here are some tips to help with skin irritation:

  • Don’t put any creams on the treated area of your skin without checking with your nurse or radiographer.
  • Wash your hair or scalp gently with lukewarm or cool water. Use non-perfumed shampoo or soap.
  • Pat your hair or scalp dry gently with a soft towel. Don’t rub it and avoid using a hair dryer.
  • Wear a scarf or hat to protect your head from the sun or cold.
  • If you shave your head, use an electric razor instead of wet shaving.

Skin reactions usually start to get better two to four weeks after radiotherapy.

Your skin in the treated area may be more sensitive to the sun after treatment. You may find that this area burns more easily. Take extra care in the sun during treatment and for at least a year afterwards. Cover up or use suncream with a sun protection factor (SPF) of at least 30.

Feeling sick

Your doctor can prescribe anti-sickness drugs (anti-emetics) to help. If you don’t feel like eating, you can try replacing meals with nutritious, high-calorie drinks. You can get these from most chemists and some can be prescribed by your doctor.

Late effects

Radiotherapy may cause side effects that develop months or more often some years after treatment. These are called late effects. Newer ways of giving radiotherapy are better at protecting healthy brain tissue so late effects are becoming less common.

Your specialist will talk to you about the risk of late effects before your treatment starts. Let them know if you are worried about any side effects. The benefits of having radiotherapy usually far outweigh the risk of late effects.

The following are possible late effects you might experience:

  • There may be changes to your memory, thinking and reasoning. This is called cognitive impairment.
  • You might develop a cataract if you have radiotherapy close to your eye. The clear lens of the eye becomes cloudy and blurred and you can’t see as well. Cataracts can usually be easily treated with a small operation.
  • You might experience changes in your hormone levels if your treatment involves the pituitary gland. This can cause different symptoms, including changes to your periods, sex drive or your thyroid gland.
  • There is a chance of developing a second cancer in the treated area years later. This is rare.

After treatment, you will have regular check-ups with your doctor and nurse. Let them know about any side effects so they can help.

Back to Radiotherapy explained

Before your radiotherapy

Before you start radiotherapy, your team will explain what your treatment involves and how it may affect you.

Your radiotherapy team

You will meet many different specialists from your radiotherapy team. You may see them before, during and after radiotherapy treatment.