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Side effects of radiotherapy

Find out about the side effects of external radiotherapy and how to cope with them.

Radiotherapy sometimes causes side effects during the treatment. You may not notice these effects until you have had a couple of weeks of treatment. They start to get better when your treatment ends.

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

Side effects can include:

You are likely to feel very tired during your treatment. It tends to get worse as the treatment goes on. You might also feel weak and lack energy.

After a while you may need to sleep after each radiotherapy session. Rest when you need to.

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

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

Your skin might go red or darker in the treatment area. You may also get 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 also feel sore. Your radiographers will give you creams to soothe the skin. The soreness usually goes away within 2 to 4 weeks of ending the treatment.

Tell the radiotherapy staff if you notice any skin changes.

Swelling of the breast

Radiotherapy can cause problems with the drainage of fluids. This can cause swelling of the breast or chest area. Doctors call this lymphoedema.

The swelling usually goes down a few weeks after the treatment ends. But tell your doctor or radiographers if it doesn’t. They can arrange you to see a lymphoedema specialist. You might have a type of massage called manual lymphatic drainage. 

Firmer breast

After radiotherapy, the breast may feel hard and less stretchy. This is due to a side effect called radiation fibrosis. This side effect is usually mild.

Shrinking of breast tissue

Sometimes the breast may shrink over time. This is because radiotherapy can make the breast tissue to contract. And get gradually smaller.  

Your hair may fall out in the chest and the area under the arm (armpit).

Radiotherapy may cause you to have less movement in your arm and shoulder. And this can affect your activities and work. This side effect usually improves once the treatment finishes. And you can do exercises to help.

Long term side effects

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

There are things you can do to deal with the long term side effects. And you may not have all the effects mentioned. Most of these side effects are rare. Long term side effects can include: 

Some women get a swelling in the arm called lymphoedema after radiotherapy to the armpit, particularly if they have had surgery there too.

Now specialists do not recommend having both surgery and radiotherapy to the armpit because of the increased risk of lymphoedema. But surgery and radiotherapy to the armpit may both be needed if the lymph nodes there contain cancer cells.

The treatment area might look permanently tanned after your treatment has finished. This is not harmful.

Later, you may appear to have very tiny broken veins in the skin called telangiectasia.

You can cover up any skin changes with camouflage make up. Your GP can prescribe it.

There are different colours for all skin tones. Some clinical nurse specialists are trained in showing you how to apply it.

Your consultant or GP can refer you to the skin camouflage service run by Changing Faces. This free service teaches you how to apply the make up and creams. It can also advise you on the best products to buy. 

A cough and breathlessness happen in about 1 out of 25 people who have radiotherapy to the chest area. The problems are due to changes in the lung tissue called chronic radiation pneumonitis. They might start many months or a few years after treatment.

Let your doctor know if you notice any changes in your breathing or if you cough up a lot of mucus.

You may have regular tests to check how well your lungs work. Treatment with steroids or other medicines can help you to breathe more easily.

Some people who have radiotherapy to their left breast may have changes to their heart many years later. This is a rare long term side effect.

Radiotherapy can make the bones weaker. And this can cause you to break your bones easier. Radiotherapy to your breast may cause you to have a higher risk of fractures to your ribs.

Information and help

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