Having radiotherapy to the chest can cause shortness of breath during and after radiotherapy. Shortness of breath will usually improve a few weeks after treatment but for some people it can continue long term. 

Short term effects on the lungs

Radiotherapy to the chest area can cause:

  • a cough
  • shortness of breath


If you have lung cancer you may have an increase in your cough and sputum which may contain a small amount of blood. This is normal. Coughs can sometimes get worse once your treatment has finished. If you are worried, let your specialist nurse or doctor know.

Coughing up blood

If you have lung cancer, you might notice a small amount of blood in your sputum. Your specialist nurse will tell you what to do about this.

If your tumour is located close to blood vessles there is a risk of coughing up fresh blood, which rarely could be life-threatening. Your specialist will discuss this with you. If you notice any unusual bleeding, tell a member of your health care team straight away. 

Shortness of breath

Radiotherapy to the chest causes inflammation of the lungs, which is called acute radiation pneumonitis (pronounced new-mon-eye-tiss). This can make you feel more breathless.  Always let your doctor, radiographer or nurse know if you are short of breath. You may be prescribed some medication for this. This condition should improve a few weeks after treatment. 

Rarely shortness of breath might be because of a more serious condition, such as a chest infection or a blood clot in the lung. In rare circumstances, this may need urgent assessment and could become life-threatening without any treatment.

Longer term effects

After radical radiotherapy to the chest, there is a risk of long term breathing problems. Radical radiotherapy means a long, intensive course of treatment that aims to try to cure your cancer.

Long term breathing problems are called chronic radiation pneumonitis. They cause a long term cough and sometimes breathlessness.

Let your doctor or nurse know if you notice changes in your breathing any time after your radiotherapy. It might be possible to learn breathing exercises or use medicine that can help to reduce your breathlessness, but in some rare cases breathing problems may be permanent. 

You need to tell your radiotherapy doctors if you have a heart condition that makes you breathless or if you have a heart pacemaker. Radiotherapy can make heart conditions worse over many years for some people.

  • Devita, Hellman and Rosenberg's Cancer Principles and Practice of Oncology (11th edition)
    VT Devita, TS Lawrence and SA Rosenberg
    Wolters Kluwer Health, 2019

  • Cancer and its Management (7th edition)
    J Tobias and D Hochhauser
    Wiley Blackwell, 2015

Last reviewed: 
10 Nov 2020
Next review due: 
10 Nov 2023

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