Radiotherapy side effects

Different people respond in different ways and it depends what part of your body is treated. Lists of side effects can seem overwhelming but you won’t necessarily have any of them. Ask your doctor or nurse what to expect and how you can cope. 

Some side effects depend on which part of your body is being treated, so ask your doctor or nurse what to expect.

What are the common side effects?

This list might look daunting but don't worry, it's unlikely you'll experience all of these.


You may feel very tired during your radiotherapy treatment and for several months afterwards. You may need to rest more than normal and cut back on some activities for a while.

Feeling sick

You may find that your treatment makes you feel sick, especially if your treatment area is near your stomach. Your specialist may be able to prescribe anti-sickness drugs to reduce this side effect.

Changes in appetite

You may find that you don’t feel like eating during your treatment, or that your eating habits change. However, it is really important to have a healthy diet and to drink plenty of fluids to keep well during your treatment. If you are having problems with eating, ask if you can speak to the hospital dietician.

Dental problems

If you have radiotherapy to your head or neck, your mouth may become dry and dental decay may occur more rapidly. Your specialist or dentist will be able to prescribe some fluoride tablets or fluoride mouthwash.

Read why it's important to care for your teeth and oral hygiene and what you should be doing.  

Skin irritation

If you are having external radiotherapy, you may develop a skin reaction, like sunburn. If this is going to happen, it usually begins about ten days after treatment. You may notice your skin changes colour or becomes itchy. Let your specialist know if you notice any soreness or colour change in the treatment area.

Sensitive skin

The skin in your treatment area will be very sensitive, and will need to be protected from the sun and cold winds. For at least the first year after you finish radiotherapy, you will need to cover the treated area of your skin if you go out in strong sunshine.

Read more about looking after your skin during and after treatment.

Hair loss

Radiotherapy can cause hair loss in your treatment area. Depending on the type of radiotherapy you have, this may grow back several months after your treatment ends.

Read more about hair loss and looking after your hair during treatment.

Fertility issues

If your ovaries or testicles are within your radiotherapy treatment area, this may affect your ability to have children later in life. It is important to talk to your specialist about the options available to you before beginning treatment. You may be able to store eggs or sperm before your treatment begins, to use if you and a partner want to have children later.

Read more about fertility and cancer treatment.

If it's affecting your confidence

It's normal for your self-esteem to become low during and sometimes after treatment, especially if you've experienced changes to your body and how you usually look.

Here are our five tips to boost your confidence. 

Updated March 2018, next review due 2021.