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Radiation therapy side effects

You may experience different side effects during cancer treatment. These can vary depending on your cancer type, stage and the kind of treatment you are undergoing.

Radiation therapy and its effect on the body

Radiation therapy, or radiotherapy, uses radiation to safely treat and manage cancer by directly targeting the tumour, destroying cancer cells, reducing the growth and spread of cancer or relieving cancer symptoms. This can also affect your body in different ways. It’s important to understand these effects and how you can keep your body healthy throughout treatment. Every patient is different, and your doctor and care team will be able to help you manage any side effects of treatment. We encourage you to discuss any concerns you have at your consultations and throughout your treatment appointments.

Common side effects from radiation therapy

As radiation is targeted to a specific area of the body, you generally will only experience side effects in the area being treated. Your radiation oncologist and treatment team will discuss the type of side effects you may experience before your treatment begins. We use the latest, cutting-edge technology and treatments that pinpoint tumours to help minimise radiation dose to surrounding healthy tissue and organs which can reduce side effects and help maintain quality of life.

Although most side effects are temporary and resolve after your radiation therapy has finished, there is a possibility that long-term effects may occur, but it is important to note that side effects of radiation can be managed and patients are generally able to continue their daily activities. Please discuss with your radiation oncologist as he/she is the best person to provide more details and this will be covered in the consent process before you start your treatment.

Common side effects

Skin reaction

Two to three weeks after your radiation therapy begins, you may experience skin redness, dryness, itching, blistering or peeling. These skin reactions may last throughout your treatment, and will usually resolve a few weeks after treatment has finished. Sometimes these effects may worsen towards the end of treatment and for up to two weeks after your treatment ends.


During your treatment it is common to feel fatigue, a feeling of exhaustion and lack of energy. As you reach the end of your treatment, your fatigue may worsen. Every person is affected by fatigue in different ways, which may also depend on whether you are receiving other cancer treatments, such as chemotherapy. Fatigue usually resolves a few weeks after the completion of your treatment. To best manage your fatigue, it’s important to find a balance between rest and activity.

Nausea and vomiting

Nausea and vomiting can be common reactions from radiation therapy to certain areas of the body, such as the abdomen.

Bowel irritation

Radiation therapy can irritate the lower part of the bowel and you may experience some related symptoms towards the end of your treatment. Symptoms of irritation can include:

  • An increase in the amount of bowel motions
  • Softer/looser bowel motions
  • Discomfort in passing a bowel motion
  • Urge to use your bowels without passing a motion (tenesmus)
  • Bleeding from the rectum (especially if you have haemorrhoids)
  • Mucus discharge
Bladder irritation

As you progress through your treatment, radiation therapy can irritate the bladder lining and the urethra (the tube that you urinate and ejaculate through). Symptoms can include:

  • The need to urinate more often, including overnight
  • A sudden urge to empty your bladder
  • A burning sensation when you urinate
  • Change or reduction in your urine flow/stream and/or difficulty urinating
  • Blood in the urine
Sexual function

The effect of radiation therapy to sexual function can be different for everyone and will depend on the area being treated. You can continue sexual activity without causing harm to your partner. However, it is important to use contraception to avoid pregnancy during treatment.

Radiation therapy to the prostate can damage the nerves that control erections and this may affect your ability to maintain an erection or you may feel a burning sensation during ejaculation. Your desire to have a sexual relationship may also decrease during treatment.

Pain and discomfort

Radiation therapy can cause a temporary increase in pain, swelling and aches in the area being treated. In most cases this pain can be easily managed.

Hair loss

If you have hair in your treatment area, you may lose some or all of it a few weeks after treatment begins. Hair will usually regrow within three to six months. The colour or texture may be different, and it may grow back thinner or patchy.

Occasionally, hair loss can be permanent if you have a high dose of radiation therapy. Your doctor will discuss this with you before you start your treatment.

Difficulty swallowing

Difficulty swallowing is a common reaction when the throat or oesophagus is in the treatment area. The throat may become inflamed and feel painful when swallowing or produce a sensation like a lump in the throat.

Changes in the mouth

Radiation therapy to the head and neck may cause changes in the mouth such as a temporary change or loss of taste, dry mouth, oral thrush and mouth ulcers.


Whether fertility is impacted by radiation therapy depends on the area that is receiving treatment. If you are a woman having radiation therapy to the abdomen or pelvis, the amount of radiation absorbed by the ovaries will determine the potential impact on your fertility. Radiation to the pituitary gland may also affect your fertility, as this gland normally signals the ovaries to ovulate.

Radiation to both testes in men is rare. However, if this is part of your treatment plan your fertility will be affected. If the radiation fields include the pelvis, for example in the treatment of rectal, prostate or soft tissue sarcoma at the buttock or upper leg areas, there may be scattered radiation doses to the testes that can affect your fertility and this can be temporary or permanent depending on the radiation doses received.

Please speak with your radiation oncologist if you or your partner wish to become pregnant or you have fertility concerns.

Pregnancy and fathering children during treatment

You must not be pregnant, become pregnant or father children at any point during your radiation therapy, as radiation can cause congenital abnormalities and increases miscarriage risk.

If you think you might be pregnant at any time, it is extremely important to discuss this with a member of your care team. Adequate protection, such as the use of condoms during sexual intercourse or using birth control pills, is needed to ensure that you or your partner do not become pregnant during the course of radiation. If you want to become pregnant or father children after your treatment please talk to your radiation oncologist about this before starting radiation therapy.

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