Side effects of external radiotherapy

Side effects can be mild or troublesome, depending on the strength of the radiotherapy dose and the length of your treatment. Your doctor will let you know what to expect.

You may experience some of the following side effects:

  • Lethargy and loss of appetite: The radiotherapy will make you feel tired and you may lose your appetite.
  • Diarrhoea: Radiotherapy may irritate the bowel and cause diarrhoea. This occurs when your stools are loose and watery and you have frequent bowel movements.
  • Hair loss: Radiotherapy can cause hair loss in the area being treated, such as your pubic hair, and this may be permanent.
  • Menopause: Radiotherapy to the pelvic region may cause menopause.
  • Shortening and narrowing of the vagina: Radiotherapy to the pelvic area can affect the vagina, which will become tender during the course of radiotherapy and for a few weeks after it ends. In the long term this irritation can make the vagina drier and can leave scarring that makes the vagina shorter, narrower and less flexible. This may make sex uncomfortable or difficult. To keep your vagina open and supple, use a dilator, which is a tube-shaped device made of plastic or rubber, to keep the vagina open. Your health care team can show you how to use a dilator. A water-based vaginal lubricant can help relieve painful irritation. Avoid Vaseline or other oil-based lubricants as they may cause irritation. If you are ready and able, have regular gentle sex to help widen the vagina.
  • Cystitis: Radiotherapy to the pelvic area can also cause a burning sensation when passing urine (cystitis). These side effects can be mild or troublesome depending on the strength of the radiotherapy dose and the length of your treatment.
  • Skin changes. Your skin may get red, itchy, dry or swollen in the area being treated. Use lukewarm water to shower or bathe, and a mild soap that does not have fragrance or deodorant in it. Ask your radiographer or nurse for advice on any skin problems.

When you’re having radiotherapy, you should allow yourself plenty of time to rest. You should also try to drink lots of water and have small, frequent meals. Ask your doctor or nurse about ways to manage side effects.

The Cancer Council booklet, Understanding Radiotherapy, has more information about managing the side effects of radiotherapy. It is available free online or by calling the Cancer Council Helpline (13 11 20).

Side effects of internal radiotherapy

While the needles are in place, the tissues around them will become swollen. This usually settles by the time the needles are removed.

The treated area will become sore about 5–10 days after the needles or wires have been removed, and this may last for several weeks. Your doctor can prescribe painkillers to help relieve the discomfort.

Side effects may continue for several weeks and then gradually disappear once your course of treatment is over. It is important to tell your doctor if they continue so that they can be treated.

The Cancer Council booklet, Understanding Radiotherapy, has more information about managing the side effects of radiotherapy. It is available free online or by calling the Cancer Council Helpline (13 11 20).