Radiation therapy

Side effects of radiation therapy

Radiation therapy is an effective treatment for many cancers, but it can also injure healthy cells at or near the treatment area. This can lead to side effects. Before recommending any treatment, the radiation oncologist will consider whether the potential benefits outweigh the possible side effects. To minimise side effects, a range of new techniques have made radiation therapy highly precise.

Some people experience many side effects, while others have very few or none. Side effects can be different even with the same type of radiation therapy to the same part of the body. Many factors can affect the type and severity of side effects, including: the part of the body treated; the type of radiation therapy; the dose of radiation needed; any other treatments you might be having; and your general health. If you have severe side effects, the radiation oncologist may change the treatment or prescribe a break, but will advise against this if it would affect how well the treatment works.

It is important to maintain your general health during treatment. People with diabetes in particular should ensure the condition is well managed as it can interfere with effective healing – see your general practitioner (GP) before treatment starts.

Your treatment team can suggest ways to ease side effects. Check with your radiation oncologist before using any over-the-counter medicines, vitamins, creams or other therapies, as some may affect the way radiation therapy works or make side effects worse.

How long side effects may last

Radiation therapy can cause side effects during and just after treatment – these are called short-term or acute effects. It can also cause long-term or late effects months or years down the track.

Short-term side effects

For short courses of treatment lasting 1–5 days, you may notice side effects from the first day of treatment. For longer courses, side effects often build up gradually during treatment and it could be a few weeks before you notice anything. Often the full impact comes at the end of treatment or even a week or two afterwards.

During treatment, tell your radiation oncology team about any side effects, as they can usually be controlled with the right care and medicine. Most side effects are temporary and go away in time, usually within days to weeks of treatment finishing.

Long-term or late effects

Radiation therapy can also cause effects months or years after treatment. These late effects are usually mild, they may come and go, and they may not have any major impact on your daily life. However, they may be more significant. Some may go away or improve on their own, while others 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.

Common side effects

The side effects of radiation therapy often relate to the type of cancer and the part of the body treated, so it can be useful to read the information about the type of cancer you have. You can call Cancer Council  on 13 11 20 for more information. The table below lists some common side effects of radiation therapy but you are unlikely to experience all of them.

Short-term side effects

  • Skin problems
  • Appetite loss
  • Nausea
  • Mouth and throat problems
  • Bladder problems
  • Bowel problems
  • Hair loss
  • Lymphoedema 
  • Sexuality and intimacy issues

Long-term or late side effects

  • Bladder problems
  • Bowel problems
  • Lymphoedema 
  • Tissue hardening (fibrosis)
  • Sexuality and intimacy issues
  • Infertility


Feeling exhausted and lacking energy for day-to-day activities is a common side effect of radiation therapy. During treatment, your body uses a lot of energy dealing with the effects of radiation on normal cells. Fatigue can also be caused by travelling to treatment and appointments. It usually builds up slowly during the course of treatment, particularly towards the end, and may last for some weeks after treatment finishes. Many people find that they cannot do as much as they normally would, but others are able to continue their usual activities.

Tips for managing fatigue

  • Listen to your body. If you feel tired, rest.
  • Try to spread activities out through the day.
  • Ask family and friends for help, e.g. with shopping, housework and driving.
  • Take a few weeks off work during or after treatment, reduce your hours, or work from home. Discuss your situation with your employer.
  • Do some light exercise, such as walking. Regular exercise
  • may give you more energy and make you feel less tired. Talk to your treatment team about suitable activities for you.
  • Limit caffeinated drinks, such as cola, coffee and tea. While caffeine may give a burst of energy, it can make you feel jittery and irritable, and cause insomnia and dehydration.
  • Limit your alcohol intake. Also try to quit smoking if you smoke.
  • Eat a healthy, well-balanced diet, and don't skip meals.

Skin problems

External beam radiation therapy may make skin in the treatment area dry and itchy. Your skin may look red, sunburnt or tanned. Less commonly, it may peel and feel painful. Skin changes often start 10–14 days after the first treatment and improve with time. You may need dressings and creams to assist healing, avoid infection and make you more comfortable, and you might be prescribed a special moisturiser. Pain medicine can help if the skin is very sore. Let your treatment team know about skin changes, such as cracks or blisters, moist areas, rashes, infections or peeling.

Tips for caring for your skin

  • Follow skin care instructions from your treatment team as soon as treatment starts, even before you notice any skin changes. Check with your treatment team before using any over-the-counter creams.
  • Avoid using razors, hair dryers, hot water bottles, heat packs, wheat bags or icepacks on the area.
  • Bathe or shower in lukewarm water, as hot or very cold water can damage sensitive skin. Do not use harsh soaps or other products. Pat skin dry with a soft towel.
  • Let skin markings wear off gradually. Don't scrub your skin to remove them.
  • Wear loose, soft cotton clothing. Avoid tight-fitting items, belts or collars over the treatment area.
  • Cover your skin before going outside and stay out of the sun when you can.
  • Avoid chlorinated swimming pools, spas and saunas.

Appetite loss and nausea

Good nutrition is important during and after cancer treatment. It can help to manage the side effects of treatment and speed up recovery. However, some people may lose interest in food or find it difficult to eat well during radiation therapy. This can depend on the part of the body being treated.

With radiation therapy to the abdomen (including stomach and bowel), pelvic region or head, some people feel sick (nauseous) or even vomit after a treatment session. Your radiation oncologist may prescribe medicine to take at home before and after each session to prevent nausea. If you are finding nausea difficult to manage, talk to the radiation oncologist or nurse about some strategies, or call Cancer Council 13 11 20.

If you have radiation therapy to the head and neck area, chewing or swallowing may be difficult or painful. Your sense of taste may also change if radiation therapy has affected the salivary glands or tastebuds. See ways to manage these effects and maintain good nutrition.

For more information about appetite loss, nausea and nutrition, see Nutrition and Cancer or call Cancer Council 13 11 20.

"At first, I couldn't think about eating without thinking about throwing up. Drinking ginger beer helped control the nausea." – Simon

Managing appetite loss

  • Eat smaller amounts as often as possible rather than a few large meals.
  • Try to eat extra on days when you have an appetite.
  • Ask a dietitian for advice on the best eating plan during treatment and recovery.
  • If you don't feel like eating solid foods, try enriching your drinks with powdered milk, yoghurt, eggs or honey.
  • Do not use nutritional supplements or medicines without your doctor's advice, as some could interfere with treatment.
  • Cooking smells may put you off eating. It might help if someone else prepares your food, or you could consider reheating precooked meals.
  • Try to do some light physical activity, such as walking. This may improve your appetite.

Managing nausea

  • Have a bland snack, such as toast and apple juice, before each session. You may find that ginger or peppermintflavoured food and drinks help to reduce nausea.
  • Sip on water and other fluids throughout the day to prevent dehydration.
  • Eat dry biscuits, crackers or toast.
  • Some people find that anti- nausea medicine helps. Ask your doctor for a prescription, and tell them if the prescribed medicine doesn't help – it may take some time to find one that works for you.
  • Contact your doctor if the symptoms of nausea don't improve after a few days, or if you have been vomiting for more than 24 hours.

Mouth and throat problems

Radiation therapy is often used to treat cancer in the mouth, throat, neck or upper chest region. Depending on the area treated, radiation therapy may affect your mouth and teeth. This can make eating and swallowing difficult and change your sense of taste.

Treatment to the mouth may increase the chance of tooth decay or other problems in the future. You will need to have a dental checkup before treatment starts and regular check-ups after it finishes.

If you're seeing a dental specialist, such as an orthodontist, ask if they can liaise with your usual dentist about any work you need to have before radiation therapy starts. Your dentist can give you detailed instructions about caring for your mouth to help prevent tooth decay and deal with side effects such as mouth sores.

Dryness and other issues

After several weeks of treatment, your mouth or throat may become dry and sore, and your voice may become hoarse. Radiation therapy can affect your salivary glands so you produce less saliva, which can contribute to the dry mouth. These effects will gradually improve after treatment finishes, but it may take several weeks or even months. In some cases, the effects may improve but not completely disappear.

You may have thick phlegm in your throat, or a lump-like feeling that makes it hard to swallow. Food may also taste different. Taste changes may last for many months after treatment, but normal taste usually returns eventually.

Tips for managing mouth and throat problems

  • If possible, have a dental check-up before treatment begins with a dentist who specialises in the effect radiation therapy has on teeth.
  • Keep your mouth moist by sucking on ice chips and sipping cool drinks. Carry a bottle of water with you.
  • Ask your doctor, nurse or pharmacist for information about artificial saliva to moisten your mouth.
  • Avoid tobacco and alcohol, as they will irritate your mouth and make dryness worse.
  • If chewing and swallowing are painful, try to consume more liquids or soft food. Talk to a dietitian, who can suggest nourishing foods that will not hurt your mouth.
  • If you have trouble swallowing, ask your doctor for a referral to a speech pathologist.
  • To manage taste changes, try different ways of preparing food. For example, add lemon juice to meat and vegetables, marinate foods or add spices.
  • Talk to your doctor if eating is uncomfortable or difficult. If you are in pain, ask for pain medicine, which may help with swallowing.
  • Rinse your mouth regularly using an alcohol-free mouthwash recommended by your doctor or dentist. Saltwater is a natural disinfectant – you can make a saltwater mouthwash at home by dissolving 1/4 teaspoon of salt into 1 cup of warm water. Rinse your mouth with plain water afterwards.
  • Call 13 11 20 or visit your local Cancer Council website for more information. The Nutrition and Cancer section includes recipes for soft meals, and you'll find many tips in the fact sheets Understanding Taste and Smell Changes and Mouth Health and Cancer Treatment.

Bladder problems

Radiation therapy to the abdomen or pelvic area can irritate the bladder or, more often, the urethra (the tube that carries urine from the bladder to the outside of the body).

Possible bladder changes include:

  • some stinging when you pass urine
  • a little blood in the urine
  • needing to pass urine more often, especially at night
  • a weaker stream of urine than before
  • leaking urine, for example, when you cough or sneeze.

To help manage these side effects, drink plenty of fluids and avoid strong coffee, tea and alcohol. Let your treatment team know if you are experiencing bladder or urinary problems, as they will be able to suggest strategies and may recommend medicines. You can also call the National Continence Helpline on 1800 33 00 66.

Bowel problems

To reduce the effects of radiation on the bowel, the radiation therapists may advise you to drink fluids before each session so you have a full bladder. This will expand your bladder and push the bowel higher up into the abdomen, away from the radiation.

Even with precautions, radiation therapy can irritate the lining of the bowel or stomach. This may lead to side effects such as:

  • frequent loose bowel movements or diarrhoea
  • abdominal cramps
  • minor bleeding
  • feeling an urgency to empty the bowels even though
  • little faeces is passed
  • mucus in the faeces
  • excess wind
  • discomfort opening the bowels.

Talk to your treatment team about ways to manage any bowel issues that occur. You can also visit the Australian Government's Bladder and Bowel website.

Tips for managing diarrhoea

  • Avoid high-fibre and spicy foods, e.g. wholegrains, nuts, legumes and curries, which can trigger diarrhoea.
  • Drink lots of clear liquids when you first notice symptoms of diarrhoea to avoid dehydration. Try apple juice, weak tea and clear broth.
  • Eat or drink as well as you can so your body gets the energy and nutrients it needs.
  • Check with your treatment team before taking any home remedies. You may be prescribed medicine to relieve diarrhoea, and taking them together may cause unwanted effects.
  • Slowly reintroduce fresh fruits, vegetables, and wholegrain breads and pasta after the diarrhoea has stopped.
  • Contact your treatment team immediately if there is blood in your bowel motions or if you have more than 5–6 bowel movements in 24 hours.

Hair loss

If you have hair in the area being treated, you may lose some or all of it during or just after radiation therapy. The hair will usually grow back a few months after treatment has finished, but sometimes hair loss is permanent.

When cancers on one part of the face or head are treated, hair on the other side of the head may be lost due to radiation passing from one side to the other.

Tips for managing hair loss

  • Wear a wig, toupee, hat, scarf or turban, or leave your head bare. Do whatever feels comfortable and gives you the most confidence.
  • If you prefer to leave your head bare, wear a hat, beanie or scarf to protect your head against sunburn and the cold.
  • If you plan to wear a wig, choose it before treatment starts so you can match your own colour and style. For information about wig services, you can call Cancer Council on 13 11 20.
  • As your hair grows back, talk to your hairdresser or barber about how to style it. It may be thinner, or curly where it was once straight, and the new growth may be patchy for a while.
  • Contact Look Good Feel Better. This program teaches techniques to help restore appearance and improve self-confidence. For details, visit lgfb.org.au or call 1800 650 960.
  • Visit your local Cancer Council website to read the Hair Loss fact sheet.


The body's lymphatic system filters the blood and helps to fight infection. It is made up of a network of lymph vessels that transport lymph fluid throughout the body. Along the lymph vessels are many small, bean-shaped structures known as lymph nodes (glands).

Sometimes radiation therapy damages lymph nodes or lymph vessels in the area being treated, especially if some lymph nodes have already been removed by surgery. Because the lymph fluid no longer drains properly, it can build up and cause part of the body to swell. This swelling is known as lymphoedema. It usually occurs in an arm or leg, but can also affect other parts of the body.

Lymphoedema or swelling is sometimes just a temporary effect of radiation therapy, but it can be ongoing. It can also be a late effect, appearing months or even years after the treatment.

Early diagnosis of lymphoedema allows the condition to be well managed, so let your treatment team know if any new swelling appears. In some hospitals, a lymphoedema practitioner can assess your risk of developing lymphoedema and give you some simple exercises to help you reduce your risk and regain movement. To prevent lymphoedema getting worse, it is very important to avoid infection in the swollen area.

For more information about lymphoedema, call Cancer Council on 13 11 20 or look for our Understanding Lymphoedema fact sheet on your local Cancer Council website.

Radiation therapy can cause the skin or internal tissue to become less stretchy and harden. This is known as fibrosis. It can occur weeks or months after treatment and have a range of impacts, such as pain, lack of flexibility and narrowing of passages (such as the vagina or rectum). Let your treatment team know if you start experiencing any new pain or stiffness, as early treatment can help.

Sexuality and intimacy issues

Radiation therapy can make you feel too tired or sick to want to be intimate. Some people may feel less sexually attractive to their partner because of changes to their body. Talking to your partner or a counsellor about your concerns may help.

You might find it useful to read Sexuality, Intimacy and Cancer. Call Cancer Council on 13 11 20 for more information.

Radiation therapy to the pelvic region

This can make sexual intercourse uncomfortable. You may notice a change in your sexual desire (libido). These changes are common and may be only short term.

Effects on women

Radiation therapy to the pelvic area usually affects the ovaries. This can cause women to stop having periods, which is called menopause. The symptoms of menopause include hot flushes, dry skin, vaginal dryness, mood swings, trouble sleeping (insomnia) and tiredness. Talk to your doctor or call Cancer Council on 13 11 20 for ways to manage these symptoms.

If the vagina is treated with radiation therapy, it may become inflamed and intercourse could be painful. This usually settles down in the weeks after you finish treatment.

Down the track, the vagina may remain dry and can get tighter and shorter. This can make intercourse difficult or painful. Shortening and tightening of the vagina can be prevented by having regular intercourse or using a device called a vaginal dilator. Your treatment team can provide you with a dilator and instructions for how to use it.

Effects on men

Men may have problems getting and maintaining erections, and ejaculation may be painful for a few weeks after treatment. For some men, the difficulty with erections may be permanent.

Talk to your radiation oncologist if these effects are ongoing and causing you distress. They can suggest ways to manage them, such as the use of prescription medicine.

Using contraception

Your doctor may talk to you about using contraception during and after radiation therapy. Although radiation therapy often affects fertility, a woman could still become pregnant (unless the reproductive organs have been removed during surgery). A man having radiation therapy could get his partner pregnant.

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. If pregnancy is possible, your doctor will advise you to use contraception or avoid sexual intercourse 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.

In some cases, your doctor may recommend you use a barrier method of contraception (such as a condom or a female condom) for a certain period of time. This is to prevent the risk of infections if the lining of your genitals is inflamed and sore.


Depending on the area treated, radiation therapy can temporarily or permanently affect your ability to have children (fertility).

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 future and ask what can be done to reduce the chance of problems and whether you should see a fertility specialist beforehand. It is important to realise, however, that sometimes it is not possible to properly treat the cancer and maintain fertility.

Radiation therapy to the brain can affect the pituitary gland, which controls the hormones the body needs to produce eggs and sperm. Radiation therapy to the abdomen, pelvis and reproductive organs can affect the fertility of women and men in different ways.

Effects on women

Treatment to the pelvic area or abdomen can affect the ovaries and cause periods to stop permanently, leading to menopause and infertility. If you wish to have children in the future, talk to your radiation oncologist before treatment starts about ways to preserve your fertility, such as storing eggs or embryos.

Effects on men

Radiation therapy to the pelvic area or near the testicles may temporarily reduce sperm production. You may feel the sensations of orgasm, but ejaculate little or no semen. This is called a dry orgasm.

Semen production often returns to normal after a few months. For some men, the effect is permanent and causes infertility. If you want to father a child, you may wish to store sperm before treatment starts so your partner can conceive through artificial insemination or in vitro fertilisation in the future.

Radiation therapy may also affect the ability to get erections. Discuss this and any other fertility concerns with your radiation oncologist.

Many people experience 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. For more information about infertility, see Fertility and Cancer or call Cancer Council on 13 11 20.

Key points

  • The side effects you experience will depend on the type and dose of radiation therapy, the part of the body being treated, your general health and other treatments you might be having.
  • Your health care team can suggest ways to prevent and manage side effects.
  • Some effects occur months or years after treatment finishes. These are called late effects.
  • Fatigue is common during radiation therapy. Try to plan activities around your energy levels, and ask family and friends for help.
  • If your skin is red or sore, use creams recommended by the radiation oncology nurse. Protect your skin when you go out in the sun.
  • A dietitian can advise you on a suitable eating plan.
  • You may experience nausea and diarrhoea after treatment to the abdomen or pelvic area. Drink lots of fluids to prevent dehydration. Prescription medicine may help.
  • Let your treatment team know if radiation therapy to the head area causes difficulty swallowing. Radiation therapy to this area can also cause dryness and mouth irritation and soreness.
  • In some cases, radiation therapy causes lymph fluid to build up (lymphoedema) or tissue to harden (fibrosis). Seek treatment as soon as symptoms appear.
  • Treatment may affect your fertility. If you would like to have children in the future, talk to your doctor before treatment starts.
  • You will be advised to avoid pregnancy during treatment.

Expert content reviewers:

Dr Tiffany Daly, Radiation Oncologist, Radiation Oncology Princess Alexandra Raymond Terrace (ROPART), South Brisbane, QLD; Elly Keating, Acting Principal Radiation Therapist, Northern Territory Radiation Oncology, Alan Walker Cancer Care Centre, NT; Julie O'Rourke, Clinical Nurse Consultant, Radiation Oncology, Canberra Hospital, ACT; Ching Tsao, 13 11 20 Consultant, Cancer Council NSW; A/Prof Sandra Turner, Clinical Lead, Targeting Cancer Campaign, Faculty of Radiation Oncology, Royal Australian and New Zealand College of Radiologists (RANZCR), NSW; Dr David Waterhouse, Acting Principal Radiation Oncology Medical Physicist, Sir Charles Gairdner Hospital, WA; David Wells, Consumer.

Talking bubbles icon

Questions about cancer?

Call or email our experienced cancer nurses for information and support.

Contact a cancer nurse