Side effects of radiotherapy

Your radiotherapy team plans your treatment carefully to reduce your risk of side effects. But most people have some side effects during or after radiotherapy.

Side effects do not usually happen straight away. They may develop during treatment or in the days or weeks after treatment finishes. Sometimes side effects get worse for a time during and after you have finished radiotherapy before they get better. There may also be a risk of side effects that are long-term or that only start months or years after radiotherapy.

It is difficult to know exactly how you will react to treatment. Your team will explain what to expect. Always tell them if you have side effects during or after radiotherapy. They can give advice and support to help you cope.

Below are some of the general radiotherapy side effects. You are unlikely to get all of them. You may also get other side effects that we do not mention here. This can depend on:

• the area of your body being treated
• the type of radiotherapy you have
• other treatments you are also having, such as chemotherapy.

Radiotherapy only affects the area of the body being treated. You may find it helpful to read our information about the type of cancer you have. This has more detail about your treatment and the other possible side effects.

We also have more information about side effects that may affect your sex life and fertility for men and women.

At times during your treatment, you may not feel like eating. Or you may find that your eating habits change. Eating a healthy diet and drinking plenty of fluids is good for your general health. Tell your team if you are finding it difficult to eat.

Radiotherapy to some areas of the body can cause more serious side effects that may make eating and drinking difficult. This includes treatment to your head, neck or oesophagus. Your team may suggest putting a feeding tube into your stomach. You may have one of the following tubes:

• A NG tube – this is passed down the nose and into the stomach.
• A PEG or RIG tube – this tube is passed through the skin and muscle of the tummy (abdomen) and into the stomach during a small operation.

The tube is usually put in before your treatment starts. You usually only need it for a short time. You can be fed through it if you have problems eating or drinking. When you can eat and drink again, it is taken out.

Tell the radiotherapy team if you are having any problems. They can give you advice. They may be able to arrange for you to talk to the hospital dietitian. The dietitian can monitor your weight and diet more closely.

Here are some tips for coping with eating problems:

• Try having small, nutritious snacks throughout the day rather than large meals.
• If food seems tasteless, use seasoning or strong-flavoured sauces.
• It can help to avoid foods that are spicy or very hot in temperature.
• If your mouth is dry, try sipping water regularly or chewing sugar-free gum.
• If you are losing weight, add extra energy and protein to your diet. Or ask your radiotherapy team about using food supplements.

We have more information about managing eating problems.

External beam radiotherapy can cause a skin reaction in the area being treated. If this happens, it usually begins after about 10 days.

You may find your skin in the treatment area becomes red or darkens. It may also feel sore or itchy. Sometimes the skin gets very sore and it may blister, break or leak fluid. Very rarely, your team may stop treatment for a short time to allow a serious skin reaction to recover.

Skin reactions can take time to improve. They are usually better about 4 weeks after your treatment has finished. The area of skin may always look or feel slightly different to the surrounding skin.

During your treatment, you are usually advised to:

• wear loose-fitting clothes made from natural fibres, such as cotton
• wash your skin gently with soap and water and gently pat it dry
• avoid rubbing the skin
• avoid very hot things, for example heating pads
• avoid cooling pads but these may be helpful in some situations so speak to your team about using these first
• avoid wet shaving
• avoid hair-removing creams or products, including wax and laser treatment
• follow your radiotherapy team’s advice about using moisturisers and deodorants
• protect the treated area from the sun – your radiographer can give you more information about this.

If your skin becomes sore or itchy or changes colour, tell your radiotherapy team as soon as possible. They can give you advice and treatments if needed.

When you finish radiotherapy, you should protect the skin in the treated area from strong sunshine. Once any skin reaction has disappeared, use a suncream with a high SPF of at least 50.

Wear close-weave clothing and a wide-brimmed hat to protect your head and neck area. Remember, you can burn through clothing if you are out in hot sun for a long time. Your radiographer can give you more information about this.

You may be able to go swimming once any skin reaction has disappeared. Your radiographer can give you information when it is safe to go swimming after radiotherapy. Remember to use a waterproof suncream if you swim outdoors.

Some treatments can reduce the number of normal blood cells produced by your bone marrow. Bone marrow is the spongy part inside some bones.

Treatments that impact blood cells include some types of radioisotope therapy. Sometimes, it can also happen with external beam radiotherapy, especially if you have chemotherapy at the same time.

Your blood cell levels are unlikely to cause problems. They will also improve after your treatment finishes. But some people need treatment if the level of certain types of blood cells is too low.

Your team will arrange any blood tests you need during and after your treatment. Always tell your team if you have any bruising or bleeding that you cannot explain. This includes:

• nosebleeds
• bleeding gums
• heavy periods
• blood in your urine (pee) or stools (poo)
• tiny red or purple spots on the skin that may look like a rash.

You should also contact them straight away if:

• your temperature goes over 37.5°C (99.5°F) or below 36°C (96.8°F)
• you suddenly feel unwell, even with a normal temperature
• you have symptoms of an infection.

Symptoms of an infection include:

• feeling shivery and shaking
• a sore throat
• a cough
• breathlessness
• diarrhoea
• needing to pass urine (pee) a lot, or discomfort when you pass urine.

Radiotherapy to most areas of the body does not affect your ability to get pregnant or make someone pregnant. This is called your fertility.

But your fertility may be affected if you have treatment to:

• the pelvic area – the area between the hips in the lower part of the tummy
• the pituitary gland – a small gland at the base of the brain.

Radiotherapy to these areas can affect how your body produces the:

• hormones (chemical messengers) needed to control sex
• egg or sperm cells needed to start a pregnancy.

It can also cause physical changes that:

• make it difficult to get an erection or ejaculate
• mean you cannot get pregnant or carry a pregnancy.

Before you decide to have treatment, your team will explain any risks to your fertility. For some people, radiotherapy causes changes that get better with time. For others, the treatment they have to the pelvic area or pituitary gland causes permanent infertility.

Your team may talk to you about fertility preservation, if this is possible for you. This can mean collecting and freezing sperm or eggs. Sometimes collected eggs can be fertilised with sperm. If suitable embryos develop, these may be frozen.

Fertility preservation is not always possible. But it may mean some people who lose their fertility are still able to have a baby in the future. We have more information about fertility preservation for fertility for women and men.

Even if your team tell you your fertility might be affected by the treatment, it is not always possible to know when this will happen. You may still be able to get pregnant or make someone pregnant.

You should use contraception to prevent a pregnancy during your radiotherapy and for a time after. Your team can give you more information about this.

People cope with the idea of infertility in different ways. You may come to terms with it quickly and feel that dealing with the cancer is more important. Or you might find that the impact does not hit you until treatment is over.

Whatever you are feeling, there is support if you want to talk or have questions. It does not matter whether you are starting cancer treatment or had treatment in the past. You may find it helps to talk with your partner, family, friends, or religious or spiritual adviser. If you want to talk to a counsellor, your GP or cancer doctor can help to arrange this. Fertility clinics also provide counselling.

Organisations such as the British Infertility Counselling Association (BICA) can offer support and counselling to people affected by infertility. Talking to other people in a similar position may also help you feel less alone. Get in touch with our Online Community at macmillan.org.uk/community.