Radiotherapy side effects

Radiotherapy affects people in different ways, so it is not possible to predict exactly how you will respond to the treatment.

This page gives a general overview of the more common side effects associated with radiotherapy, whichever part of your body is being treated. For side effects specific to your particular treatment area, speak to your specialist.

Your care team can help you manage these, and other, side effects. Some side effects depend on which part of your body is being treated, so ask your doctor or nurse what to expect. In general, people having radiotherapy might have the below side effects.


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 (also called anti-emetic 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.

Skin irritations

If you are having external radiotherapy, you may develop a skin reaction, like sun burn. 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.

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.

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.

Updated December 2014, next planned review 2017.