Side effects often build up slowly during treatment and it could be a few days or weeks before you notice anything. Often the side effects are worse at the end of treatment, or even a week or two afterwards, because it takes time for the healthy cells to recover from radiation. Most side effects are temporary and go away in time, usually within a few weeks of treatment finishing. 

Radiation therapy to the chest, particularly when combined with chemotherapy, may lead to an increased risk of heart problems. Newer radiation therapy techniques have reduced the risk, however, talk to your doctor about your heart health. If you develop heart problems later in life, make sure you let your doctors know you had radiation therapy. 

Radiation therapy can also cause side effects that last for months or years after treatment. These long-term effects are usually mild, they may come and go, and they may not have any major impact on your daily life. However, sometimes they may be more serious. Late side effects may go away or improve on their own, but some may be permanent and need to be treated or managed.

Very rarely, years after successful treatment, patients can develop a new unrelated cancer in or near the area treated. The risk of this late effect is very low, but other factors, such as continuing to smoke or very rare genetic conditions, can increase this risk.

• Clean your skin with warm water and a mild unscented soap. Gently pat skin dry with a soft towel rather than rubbing it.
• Ask your doctor or nurse what type of cream to use to moisturise the skin.
• Start moisturising your skin from the first day treatment starts, even before you notice any skin changes.
• Let temporary skin markings wear off by themselves. Don’t scrub your skin to remove them.
• Avoid using razors, hair dryers, hot water bottles, heat packs, wheat bags or icepacks on the area that has been treated.
• Apply sunscreen and wear a broad-brimmed hat when outside. Stay out of the sun where possible.
• Wear loose, soft cotton clothing. Avoid tight-fitting items, belts, underwire bras, jewellery or collars over the treatment area.
• Avoid chlorinated swimming pools, and spas and saunas. Check with your doctor about swimming in the sea.

Appetite loss

• Eat 5–6 small meals each day rather than a few large meals.
• Try to eat extra on days when you have an appetite.
• Ask for a referral to a dietitian to get advice on what to eat during treatment and recovery. Dietitians can suggest changes to your diet, liquid supplements or a feeding tube.
• If you don’t feel like eating solid foods, enrich your drinks with powdered milk, yoghurt, eggs or honey.
• Do not use nutritional supplements or medicines without your doctor’s advice, as some could affect treatment.
• Cooking smells may put you off eating. It might help if someone else prepares your food, or you could reheat precooked meals.
• Try to do some light physical activity, such as walking. This may improve your appetite.
• Let your treatment team know if you are having trouble eating or if your weight has changed. 

Nausea

• Have a bland snack (e.g. toast and apple juice) before each session.
• Try food and drinks with ginger or peppermint to help reduce nausea.
• Sip on water and other fluids throughout the day to prevent dehydration.
• Eat dry biscuits, crackers or toast. If nausea is a problem in the morning, have a dry cracker before getting out of bed.
• Ask your doctor if you can try anti-nausea medicine. Take this as prescribed and tell your doctor if the medicine doesn’t help – it may take some time to find one that works for you.
• Contact your treatment team if the symptoms of nausea don’t improve after a few days, or if you have been vomiting for more than 24 hours. 

For more support, listen to The Thing About Cancer podcast episode on appetite loss and nausea or call 13 11 20 to speak to our cancer nurses.

This is when you have frequent loose, watery bowel motions. Diarrhoea can also cause abdominal cramping, wind and pain. After radiation therapy, you will need to go to the toilet more urgently and more often. Having diarrhoea can be tiring, so rest as much as possible and ask others for help. Diarrhoea can take some weeks to settle down after treatment has finished.

Radiation therapy to the pelvic area can damage the lining of the rectum, causing inflammation and swelling known as radiation proctitis. Symptoms may include blood and mucus in bowel motions, discomfort opening the bowels or the need to empty the bowels often, perhaps with little result.

Ask your treatment team about your risk of developing radiation proctitis. Radiation proctitis is usually short term but may be ongoing in a small number of people. If you have any ongoing problems, they may refer you to a gastroenterologist.

• Ask your doctor about suitable medicines for diarrhoea. Take as directed.
• Check with your treatment team before taking any over-the-counter or home remedies, as taking them with anti-diarrhoea medicines may cause unwanted effects.
• Drink peppermint or chamomile tea to reduce abdominal or wind pain.
• Eat or drink as well as you can to give your body the nutrients it needs.
• Do some gentle exercise, such as walking, to encourage healthy bowel movements. Check with your doctor about the amount and type of exercise that is right for you.
• Avoid alcohol and cut down on coffee, cola and other drinks that contain caffeine.
• Drink plenty of clear liquids when you first notice symptoms of diarrhoea. This helps to avoid dehydration and replaces fluids lost through diarrhoea. Try apple juice, weak tea, clear broth, sports drinks and electrolyte-replacing fluids. It may also be worth trying a lactose-free milk.
• Choose plain foods that are low in insoluble fibre (e.g. bananas, mashed potato, apple sauce, white rice or pasta, white bread, steamed white fish or chicken). Talk to your dietitian about what else you can eat.
• If you have diarrhoea, avoid high-fibre, fatty or fried foods, pulses, garlic and onion, and rich sauces and gravies, as these can make diarrhoea worse.
• The blood vessels in the bladder and bowel can become more fragile after radiation therapy. This may mean you see blood in your urine or bowel motions, even months or years after treatment. Contact your treatment team immediately if you notice bleeding, or if you have more than 5–6 bowel movements in 24 hours.

You may notice a lack of interest in sex or a loss of desire (libido), or you may feel too tired or unwell to want to be intimate. You may feel less sexually attractive to your partner because of changes to your body. All of these feelings are quite common.

Radiation therapy can also make sexual intercourse painful, difficult or uncomfortable, depending on where the radiation therapy is given. Talk to your doctor about ways to manage side effects that change your sex life.

For more support, listen to The Thing About Cancer podcast episode on sex and cancer.

A woman’s eggs (ova) and a man’s sperm can be affected by very small amounts of radiation when having radiation therapy to any part of the body. Depending on the type of radiation therapy you have, your doctor may talk to you about using a barrier method of contraception (such as a condom or female condom).

If pregnancy is possible, your doctor will advise you to avoid pregnancy by using contraception during radiation therapy and for at least six months after you have finished treatment. Talk to your doctor as soon as possible if pregnancy occurs.

The risk of infertility (difficulty getting pregnant or conceiving a child) will depend on the area treated, the dose of radiation therapy and the number of treatment sessions. If you are treated with both radiation therapy and chemotherapy (chemoradiation), the risk of infertility is higher.

Radiation therapy to the pelvic area, abdomen and sexual organs can affect your fertility, which can be temporary or permanent. Radiation therapy to the brain can damage the pituitary gland, which controls the hormones the body needs to produce eggs or sperm.

If infertility is a potential side effect, your radiation oncologist will discuss it with you before treatment starts. Let them know if you think you may want to have children in the future. Ask what can be done to reduce the chance of problems and whether you should see a fertility specialist beforehand.

Sometimes, however, it is not possible to properly treat the cancer and maintain fertility. Many people feel a sense of loss when they learn they may no longer be able to have children. If you have a partner, talk to them about your feelings. Talking to a counsellor may also help.