Side effects

Radiation therapy can cause various side effects to the area of the body being treated. Some of these are short-term and may only occur during treatment and for a short time after treatment finishes. Others may be more long-term.

It is important to remember that because everyone is different their reaction to treatment differs too. Many people experience very few, or no side effects. Your radiation oncologist will discuss possible side effects with you before your treatment starts and see you regularly while you are on treatment (oncologist or registrar assessments.)

There are many factors that determine which, if any, side effects you may experience.
They include:

  • The amount of radiation given
  • The area of your body we are treating
  • Other treatments you may be having e.g. chemotherapy

The effects of radiation on your body increase gradually over the course of treatment. It is unlikely you will experience any side effects straight away. Side effects tend to develop after a week or so, reaching a peak approximately 10 to 14 days after your treatment finishes and then gradually subside.

If you are experiencing any side effects please tell a radiation therapist and/or radiation oncologist. Many side effects can be well managed.

Some side effects are general while others depend on what part of the body we are treating.
The most common general side effects are:


  • It is possible treatment may make you feel tired or generally fatigued. This is because your body is working to repair radiation damage to normal, healthy tissue.
  • It is important to keep hydrated and rest when you need to. Travelling in for treatment each day can be tiring in itself.

For further information see the cancer society booklet - Managing Cancer Fatigue(external link) 

Skin reaction

  • Radiation therapy can affect skin in the area being treated.
  • Some people don't notice any change whilst others experience symptoms similar to sunburn.
  • Your skin may become red, or darker, itchy and sore.

Your radiation oncologist and radiation therapy team will provide you with information about specific side effects that you may experience with your course of treatment.

If you are experiencing any side effects please let your treatment team know.