Side effects of radiation treatment

Also called radiotherapy or radiation therapy (haumanu iraruke) side effects

Key points about radiation treatment side effects

  • Not everyone has the same reaction to radiation treatment.
  • Side effects depend on the amount of radiation given, the area of the body treated, the type of radiation used and the individual response.
  • Fatigue (hiamoe, feeling very tired or worn out) is one of the most common side effects for people have radiation treatment. 
  • Other side effects include nausea, changes to the skin, hair, appetite, bladder or bowel, mouth and throat, lymph nodes and sexual functioning.
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Side effects of radiation treatment are commonly grouped into:

  • Acute side effects: Those that develop early on, during, or at the end of the treatment.
  • Late side effects: Those that develop many months, if not years, later.

Acute side effects

The inflammation caused by the radiation beams passing through normal tissue results in the acute side effects. These are the most common side effects of radiation treatment and are relatively mild and short-livedThey peak about a week after the treatment has finished. Most side effects will be greatly improved by about 6 weeks after the treatment has finished. Some common acute side effects are: feeling tired, sore skin, hair lossnot wanting to eat, feeling sick/nausea, diarrhoeamouth and throat problemsloss of interest in sex, and erectile dysfunction. Your treatment team will tell you what you are likely to experience.

Late side effects

Late or long-term side effects appear many months or years after radiation treatment. The inflammation of the tissues will have settled, but sometimes the healing process results in scarring and damage to these tissues, which will restrict their function. Your treatment will have been planned specifically to minimise the likelihood of late complications and any significant risks that might exist will be discussed with you. Possible long-term side effects include infertilityskin changes, bowel incontinence and lymphoedema.

The rest of this page provides information about the acute and late side effects and how you might manage them.

Fatigue/tiredness is a common side effect of radiation treatment. Fatigue can be mild or can be so severe that it's hard to do the things you would normally do. If you do get tired try to take things easier. Only do as much as you feel comfortable doing, and ask friends and whānau for help if you can. Try to plan rest times in your day. Drinking plenty of fluids, eating well and having some form of physical activity will also help.

Even thought you're tired, you may not be sleeping well. If this is the case, tell your treatment team. They might be able to suggest ways to help. It can be helpful to learn some relaxation techniques or breathing exercises. Read some more useful tips about how to manage your sleep problems.(external link) 

The skin in the treatment area may become dry, flaky, red, itchy or sore, similar to sunburn. It depends on the amount of radiation the skin receives.

Your skin may also be more sensitive than usual to the sun, so try to keep treated areas out of the sun during and after treatment. Once the reaction improves, ask your healthcare provider about using a sunscreen (SPF 30+).

Skin care

  • Wear soft, loose clothing.
  • Moisturise your skin to prevent it becoming dry and itchy.
  • Tell your treatment team about changes in your skin, such as cracks, blisters, very moist skin, rashes, infections or peeling, or any changes in your nails.
  • Don't rub, scrub or scratch treated skin or any sensitive spots.
  • Follow skin care advice given by your treatment team, eg, avoid using soap, perfume, deodorant on treated areas; use a soft towel; bath or shower in lukewarm (not hot) water.
  • Don't put hot-water bottles, ice packs or bandages on treated areas.
  • Stay out of swimming pools during treatment because the chemicals used are likely to cause a skin reaction.
  • Keep your nails clean and short.
  • If your skin becomes sore, only use products recommended by your treatment team.

You may lose some or all of your hair in the treatment area, eg, scalp, chest or face. This may be temporary or permanent. 

This usually starts to happen 2–3 weeks after treatment begins. Hair should start growing back a few weeks after treatment finishes; it may have a different texture or colour than before. Hair loss may be permanent if you have high-dose radiation therapy. 

If you have lost, or are losing your hair you could consider wearing a wig, hair piece, hat or scarf for a while. If you decide to wear a hair piece or wig, it's a good idea to get one fitted before you start losing your hair, so that it matches as closely as possible your style and colour. Health New Zealand | Te Whatu Ora helps pay the cost of a hair piece, wig or hair covering. Ask your healthcare provider for a certificate that states your entitlement.

Your appetite might be normal during treatment, or you may not feel like eating at all. Your sense of taste may change, especially if you've had treatment to your head and neck.

Eat as well as possible during your treatment to keep your strength up and avoid weight loss. Try different foods until you find foods that appeal. Eat smaller amounts more often, or try drinking special liquid supplement foods that you can get from your pharmacist. Even when you are unable to eat very much, it's important to drink plenty of clear fluids.

Your hospital may have its own diet information for cancer patients. You can also talk to the hospital or community dietitian for advice about what to eat. Also see: Eating well when you have cancer.(external link)

Feeling sick 

Nausea (feeling sick) and vomiting (being sick) might happen if you're having radiation to your oesophagus (gullet), stomach, bowel, brain, or pelvic area. It can help to avoid strong smells and foot that's fatty, fried, spicy or very sweet. Your radiation oncologist can prescribe medication to help relieve these symptoms. Maintaining a good fluid intake is important. If this is difficult for you, try taking small sips often or sucking on an ice cube.


During radiation treatment to the pelvic area (the lower part of the stomach/puku between the hip bones), inflammation of the large bowel (colon and rectum) and anus occurs.

You may have some of these symptoms:

  • diarrhoea (loose or runny poo, hamuti)
  • passing (pooing) blood
  • needing to rush to the toilet
  • feeling that your bowel hasn't emptied properly
  • passing excess wind (farting) a lot
  • difficulty emptying your bowel
  • bowel pain.

Keep drinking plenty of fluids and cut back on food that makes your diarrhoea worse. Ask your treatment teato recommend medicine to help control the diarrhoea.

Once the radiation treatment has ended, the inflammation usually settles down over a few weeks or months. But you may have permanent bowel changes (see late side effects). Tell your doctor if you still have diarrhoea more than 6 weeks after treatment stops or if you have blood in your poo.

Radiation treatment can give you a sore or dry mouth or throat and your voice may become hoarse – especially if you're receiving treatment to the head and neck region. Radiation treatment can also change your sense of taste so foods may taste different or have no taste at all.

Here are some ideas to try:

  • Suck on ice blocks.
  • Drink lots of liquids – carry a sipper bottle with you at all times.
  • Moisten foods with butter, gravy or sauce.
  • Dunk dry biscuits in tea.
  • Blend foods to make them easier to swallow and eat soups and ice creams.
  • Ask your treatment team or dentist about artificial saliva.
  • If you drink alcohol, do so in moderation and avoid spirits.
  • Don't smoke.

If you're having radiation treatment to your mouth, your teeth will be more likely to decay. Discuss dental care with your healthcare provider and dentist before your treatment starts, so any dental work can be arranged before your radiation treatment begins. 

If these problems interfere with eating and drinking, let your treatment team know.

Having cancer and treatment for it may have no impact on your sexuality or sex life. But sometimes the anxiety and/or depression felt after diagnosis or treatment can affect your sexual desire.

It's important for you to share your fears and needs with your partner. Other side effects like tiredness or nausea may also cause you to temporarily lose interest in sex. Sexual intercourse is only one of the ways that you can show affection for one another. Gentle touches, cuddling, and fondling can also reassure you of your need for one another. Professional support such as counselling may be helpful.


Radiation treatment to the pelvic area can cause low oestrogen levels leading to vaginal dryness as well as inflammation of the walls of your vagina. When inflammation reduces, scar tissue can form, which can make your vagina narrower and shorter. Your vaginal walls might be dry and thin, and can stick together.

Because of this you become more likely to get vaginal infections such as thrush, pelvic examinations can be uncomfortable and vaginal intercourse may be painful. To help keep your vagina supple and to prevent scar tissue from forming, you may be advised to use vaginal dilators (tampon-shaped plastic devices).

Regular sexual intercourse can also help to keep your vagina healthy, although this might be uncomfortable at first. Vaginal lubricants or moisturisers and, sometimes, oestrogen cream, may help. You can also use a vibrator or your fingers to gently stretch your vagina to keep it supple and make sexual intercourse and vaginal examinations more comfortable. Pelvic floor exercises are also helpful to reduce pain, improve bladder retention and increase blood flow to the area. Ask your healthcare provider or treatment team for more information.


In men who have radiation treatment to the pelvis, blood vessels or nerves may be damaged. This can mean it's difficult to get or keep n erection (erectile dysfunction). These effects can be distressing, and might last for several weeks after radiation treatment has finished. Sometimes impotence is permanent.

Although most men can be sexually active during treatment, there may be times when you're advised to not have sex. If you have erectile dysfunction, there are medicines and devices that may be suitable for you. Ask your healthcare provider or treatment team for more information.

If you are having pelvic radiation and/or some chemotherapy combinations, you might become infertile either temporarily or permanently. Talk to your doctor about this before you start treatment.

Despite the possibility of infertility, contraception should be used (if the woman has not gone through menopause) to avoid pregnancy. There is a risk of miscarriage or birth defects for children conceived during treatment.

If you are pregnant now, talk to your doctors immediately.

Talk to someone you trust if you're experiencing difficulties or ongoing problems with sexual relationships. Friends, family members, radiation therapists, nurses, or your doctor might be able to help. Your local Cancer Society can also provide information about sexual counselling services.

Radiation treatment is sometimes used in the treatment of skin cancers. It affects only a small area of skin and will not make you feel unwell. For a few weeks after treatment, the treated skin will be red and inflamed. During this time it will look as though the treatment has made things worse rather than better. Try not to be worried about this.

After a few weeks the area will dry up and form a crust or scab. Over another week or so the scab will peel away, leaving healed new skin underneath. It is important not to pick at the scab. At first, the new skin will look pinker than the skin around it.

Bladder changes

The cells lining the walls of your bladder can become permanently damaged. This can make them fragile so they might bleed. Your bladder walls might also become scarred and hardened (fibrosed). If this happens your bladder holds less urine. 

You might find you have some of the following symptoms:

  • The need to pass urine (pee/mimi) often (frequency). 
  • A burning sensation when you pee.
  • Being unable to wait when you need to empty your bladder (urgency).
  • Blood in your urine (haematuria).
  • Weak flow of urine and your bladder not emptying properly.
  • Needing to get up in the night to pass urine.

Occasionally people also have:

  • a small amount of urine leakage (incontinence( - especially if you laugh, sneeze, cough or when exercising.
  • pain when passing urine (peeing)
  • blood clots in their urine
  • difficulty passing urine.

Let your treatment team know if you have any of these symptoms because treatment is available for them.


If you have had surgery and radiation treatment to lymph nodes there is an increased risk of lymphoedema.

Lymphoedema is a swelling of one or more parts of the body due to a build up of fluid. Usually this happens in an arm or a leg but can occur in other parts of your body. You may notice swelling and a heavy or aching feeling (not usually painful) in the area. When you press the swollen area it leaves a dent.

If this happens to you, talk to your treatment team about ways to help. It's important to talk to your team as soon as you notice these symptoms as early treatment gives the best chance of preventing more severe problems.


Radiation treatment to the pelvic area exposes the ovaries (in women) and testicles (in men) to radiation. Pre-menopausal women may go through early menopause (when monthly periods/ikura stop) and become infertile (unable to get pregnant/hapū). Men may also become infertile, although this can be temporary or permanent.

If you want to have children/tamariki in the future, discuss this with your treatment team before having treatment. It may be possible to store eggs (in women) and sperm (in men) until you are ready.

Skin changes

After radiation therapy, you may notice long-term changes to your skin. Your skin may be thicker or darker than before, or the texture might change. These changes should gradually improve.

Bowel incontinence

After radiation to the pelvis, scarring of the bowel may mean you have bowel incontinence which can result in leaking stool/poo/hamuti. This is a rare side effect of radiation treatment. Talk to your healthcare provider about how to treat this.

Treatment symptoms and side effects(external link) Cancer Society of NZ
Radiation treatment handout(external link) Cancer Society of NZ, 2018


Supporting someone with cancer [PDF, 3 MB] Cancer Society, NZ, 2015
Radiation treatment(external link) Cancer Society, NZ, 2018
Living well with cancer – eating well [PDF, 5.5 MB] Cancer Society, NZ, 2020. Available in the following languages: English/Maori [PDF, 5.5 MB]


  1. Radiation treatment(external link) Cancer Society, NZ
  2. Radiotherapy side effects(external link) NHS Inform, UK, 2023
  3. Tiredness and fatigue(external link) Cancer Society, NZ
  4. Radiotherapy side-effects(external link) NHS, UK, 2020
  5. Fatigue and cancer treatment (external link) NIH National Cancer Institute, US, 2021
  6. Appetite loss and cancer treatment(external link) NIH National Cancer Institute, US, 2022
  7. Sexual health issues in men with cancer(external link)  NIH National Cancer Institute, US, 2022


Radiation treatment

Radiation treatment
Cancer Society, NZ, 2018

Living well with cancer – eating well

Living well with cancer – eating well
Cancer Society, NZ, 2020
English/te reo Māori

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