Radiotherapy side effects

Radiotherapy affects people in different ways, so it is not possible to predict exactly how your child will respond to the treatment. But your team at the hospital will be able to help manage any side effects.

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

Some side effects depend on which part of your child’s body is being treated, so ask your doctor or nurse what to expect. In general, people having radiotherapy might have the following side effects.


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

Feeling sick

You may find that your child's treatment makes them feel sick, especially if their treatment area is near the 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 your child does not feel like eating during treatment, or that their eating habits change. However, it is really important for your child to have a healthy diet and to drink plenty of fluids to keep well during treatment. If they are having problems with eating, ask if you can speak to the hospital dietician.

Dental problems

If your child had radiotherapy to their head or neck, their 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 your child is having external radiotherapy, they 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 child's 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 child's 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 your child finishes radiotherapy, they will need to cover the treated area of their skin if they go out in strong sunshine.

Hair loss

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

Fertility issues

If your child's ovaries or testicles are within their radiotherapy treatment area, this may affect their ability to have children later in life. It is important to talk to your specialist about the options available to them before beginning treatment.

If your child is old enough, they might want to look at our information for teenagers and young adults about fertility and how it can be affected by treatment.

Where next?

Updated November 2017, next review due 2019.