Radiotherapy - Side effects 

Side effects of radiotherapy 

Following radiotherapy, it is likely you will have some side effects. Side effects occur because radiotherapy temporarily damages some healthy cells as well as destroying cancerous ones.

Side effects will depend on:

  • the part of your body being treated
  • the dose of radiotherapy
  • how quickly the healthy cells are able to repair the damage

Radiotherapy affects different people in different ways and it is difficult to know exactly how you will react to the treatment. For some patients side effects are mild, while others experience more severe effects.

Some side effects begin during treatment whereas others can appear weeks or months afterwards.

Most side effects of radiotherapy only last for a few days or weeks after treatment has finished. However, some, such as tiredness or hair loss, can last a few months.

Before starting treatment, you should discuss the risks with your treatment team.

Common side effects

Most common side effects of radiotherapy are relatively mild and short-lived. Some are described below.

Sore skin

Your skin may become red and sore in the area being treated a few days or weeks into a course of radiotherapy, or for up to a couple of weeks afterwards.

Some people’s skin may peel (rather like sunburn). This usually heals within a couple of weeks.

Your treatment team will advise about the best way of caring for your skin during treatment. If your skin becomes sore, you should try not to irritate it further.

Avoid shaving and using perfumed soap in the affected area. Protect your skin from cold winds and wear a high-factor sunscreen (SPF 15 or above) to protect your skin from the sun.


You may feel tired both during and after radiotherapy. If you feel tired, make sure you give yourself time to rest and take naps if necessary.

Tiredness is particularly common towards the end of a course of radiotherapy and can last for some time afterwards. Doctors believe it occurs as a result of the body repairing damage to healthy cells.

A shortage of red blood cells (anaemia) can also contribute to tiredness during radiotherapy. Therefore, blood tests may be required during radiotherapy for some cancers to ensure you are not becoming anaemic. If you have anaemia, you may need a blood transfusion (where you receive blood removed from another person, known as a donor).

Feeling sick (nausea)

Most people are not sick during radiotherapy. However, some people feel sick during, or for a short time after, their treatment. If you experience nausea, your doctor may be able to prescribe medication to help control it.

Radiotherapy to your abdomen (tummy area) or pelvic area may make you sick. This can last a few days after your treatment stops. Anti-sickness medication is available to help this.

Loss of appetite

The combination of feeling sick and tired during radiotherapy can make you lose your appetite.

If you have difficulty eating, you may find it easier to eat several small meals throughout the day. You can also speak to your radiotherapist who may refer you to a dietitian (nutritional specialist).


Diarrhoea is a common side effect of radiotherapy to the abdomen or pelvic area. It usually starts a few days after treatment begins and gradually gets worse as treatment continues. Medication is available.

After your treatment has finished, diarrhoea should disappear within a few weeks. You should tell your doctor if your symptoms have not improved after a few weeks or if you notice any blood in your stools (faeces).

Hair loss

Hair loss is a common side effect of radiotherapy to your head or neck. Unlike chemotherapy, radiotherapy will only cause hair loss in the area being treated.

Many people find losing their hair distressing and difficult to cope with. Talk to your family and friends about how you are feeling so they can support you. Your treatment team may also be able to offer advice.

After a few weeks of finishing treatment, your hair should start to grow back. In some cases, the hair grows back a different colour or texture to how it was before.

Read more about cancer and hair loss.

Discomfort on swallowing

Radiotherapy to the chest can cause the tube through which food passes (the oesophagus) to become temporarily inflamed, which may cause temporary discomfort when swallowing. If required, your doctor will be able to prescribe medication to help soothe this.

You should avoid eating hot or spicy food and drinking acidic drinks or spirits during this time because they can aggravate the problem.

Effects on sex and fertility in women

Having radiotherapy may cause you to temporarily lose interest in sex, particularly if you have other side effects, such as tiredness or nausea, or if you are anxious about your condition or treatment.

Radiotherapy to the vaginal area may cause your vagina to become sore and narrower. Your radiotherapist will tell you how you can treat this using a vaginal dilator, which is a device  inserted into your vagina to help prevent it narrowing. Having sex regularly after your treatment can also help prevent your vagina narrowing.

If you experience vaginal dryness or pain when having sex, you can use lubricants or ask your GP or radiotherapist to prescribe appropriate medication.

If you have radiotherapy to the pelvic area there is also a risk of infertility (see below).

Read more about the effects on female sex and fertility on the Cancer Research UK website.

Effects on sex and fertility in men

In men, temporary erectile dysfunction (the inability to get and maintain an erection) and loss of interest in sex are common side effects of pelvic radiotherapy.

Read more about the effects on male sex and fertility on the Cancer Research UK website.

Stiff joints and muscles

Radiotherapy can sometimes cause your muscles to tighten up and your joints to become stiff in the area being treated. You may also experience uncomfortable swelling in the affected area.

Exercising regularly can help prevent stiffness. If you have stiff joints and muscles, your doctor or radiotherapist may refer you to a physiotherapist, who will recommend suitable exercises.

Read more about physiotherapy.

Long-term side effects

It is rare to develop severe, long-term side effects as a result of radiotherapy. Your doctor will discuss the likelihood that you will experience side effects before you consent to treatment.

Some possible long-term side effects are described below.

Infertility and early menopause in women

In women, radiotherapy to the pelvic area exposes the ovaries to radiation. In pre-menopausal women, this may cause early menopause (where a woman's monthly periods stop) and infertility (the inability to get pregnant). This is often very upsetting, particularly for younger women who want to have a family.

Before having treatment, your doctor will discuss all the options and available support with you. For example, it may be possible for some of your eggs to be surgically removed, frozen and stored until you are ready to have a baby.

However, this will not be possible if you need to have radiotherapy immediately and it is not available on the NHS in all areas.

Infertility in men

Radiotherapy to the pelvic area or testicles can cause infertility in men, which may be temporary or permanent.

If there is a risk that you could become infertile following radiotherapy, your doctor will discuss this with you before your treatment. It may be possible to store your sperm until you decide to have a baby, although this is not always available on the NHS.

Changes to the skin

Long-term changes to the skin can occur after having radiotherapy. Some people notice their skin is thicker, a slightly darker colour and, occasionally, dimpled (like the peel of an orange). These changes usually improve over time.

Bowel incontinence

Bowel incontinence, sometimes known as faecal incontinence, is a rare side effect of radiotherapy to the pelvis. It is the inability to control your bowel movements which can result in faeces (stools) leaking from your rectum (back passage).

Bowel incontinence can be treated with dietary changes, medicines or a number of different surgical procedures. Read more about treating bowel incontinence.


Radiotherapy can damage your body’s network of channels and glands that make up the lymphatic system. One of the functions of the lymphatic system is to drain excess fluid from your tissues.

If the lymphatic system is damaged, fluid can build up and cause swelling and pain. This is known as lymphoedema

Lymphoedema often occurs in the arms or legs, although it can also affect other areas, such as the chest. Arm lymphoedema is sometimes seen in women who have had armpit surgery or radiotherapy for breast cancer.

It may be possible to prevent lymphoedema occurring using appropriate skincare techniques and exercise. If lymphoedema does develop, it can be controlled with early treatment in a specialised lymphoedema clinic.

Second cancer

Radiotherapy is sometimes associated with a slightly increased risk of developing certain types of cancer many years after treatment (a 'second cancer').

Page last reviewed: 13/05/2013

Next review due: 13/05/2015


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The 6 comments posted are personal views. Any information they give has not been checked and may not be accurate.

Monto said on 26 April 2014

Having recently completed 5 weeks of radiotherapy with no side effects, I definitely put this down to drinking over 3 litres of water a day ( something i would never have done before), multivitamins and a high dose vitamin c every day and LOTS of moisturisation to the affected area. I was lucky enough to be able to work through the treatment - I am a nurse and worked part-time - i had treatments early afternoon and always rested in the evenings. I kept waiting for the 'tiredness' to kick-in and it never did! I went back to my full shifts a week after treatment and have not looked back since! It was quite an experience and i met so many lovely people whilst waiting for treatments and the staff in the radiotherapy area were the loveliest staff i could ask for - a positive experience. Keep positive and dont go looking for problems - good luck!

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Daxdax500 said on 08 October 2013

I am currently undergoing 6 week radiotherapy for a brain tumour. I must admit it is a lot harder than I thought. I have 2 weeks of treatment left and can't wait this to be over. In terms of side effects I suffer from severe nausea exacerbated by the smells of the treatment. My consultant has given me antiemetic drugs which help very little. For the last 2 weeks he has put me on lorazepam in addition to do peridot, the antiemetic drug. What bothers me most are the smells: the mask I am wearing exudes strong fumes which I find nauseating. During the radiation I can smell strong ozon which makes me gagg. We lots of will power I am pulling through the treatment and hope it to be over soon. The nausea increases towards the end of the week. Fatigue I don't mind so much but the nausea is awful.

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sammyc69 said on 28 July 2013

My son is having radiotherpy after a brain tumour removal..i was wondering if there are a few recomendations of handy gifts i can get him for after treatments of 6 weeks (young adult) have mouth ulcer gel...aqueous cream...suncream...any tips would be helpfull thanks.

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User744319 said on 29 January 2013

This page does say specfically that it lists "common side effects of radiotherapy", and so isn't offering an exhaustive list.

I am undergoing radiotherapy currently and am in my fourth week, and so far all I can stake a claim to is fatigue and hair loss, but nothing else - on that basis I am counting myself lucky as a mild reactor so far.

As this page says, radiotherapy affects people in different ways to different extents, but my team were very specific about telling me that - "it's different for everyone".. It could be that the cases you are referring to are sadly some of the more extreme and rarer reactions, but I'm pretty sure nobody would "refuse" to tell anyone about them. If anyone were to be unlucky enough to suffer such side effects then a quick word with their specialist would no doubt result in some encouraging support and maybe some drugs to help.

The NHS cannot cover all ends despite how hard it tries, it simply does the best it can. If you feel you've been given poor information, then maybe you should contact the web team and discuss it with them.

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phoenix 09 said on 09 September 2010

i would like to see a reply to the comment above .i t does annoy me that people savage the treatment that helps many to stay with there loved longer ,

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Blue Frog said on 25 June 2009

These listed side effects are all very well, but what about the ones they don't tell you about and in some cases refuse to tell you.
Long Term Faecal Incontinence;Pelvic Insufficiency Fractures;Bone Loss; Osteoporosis;Lymphoedema; Need for Blood Transfusions during treatment.
All conveniently ignored and yet thousands of patients suffer from them.
Stop the cover up!

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