Side Effects

Side effects are not usually experienced immediately and everyone is different. However they will usually develop about two weeks after treatment starts. Some people experience very few side effects. They only affect the area of the body being treated. You will be given support and advice about managing side effects.

Longer term side effects are rare and do not happen to everyone. They can develop months or even years after the treatment has finished. Your doctor will discuss this with you. Please let us know if you have any concerns.

Click on one of the links below for general information on some of the side effects of radiotherapy: 


The skin in the treated area sometimes becomes red and sore and it may become itchy, similar to sunburn. We will provide cream to help with any discomfort. Occasionally if the skin reaction is severe, your treatment may be delayed for a short time to allow the skin to recover. This is a normal situation so do not worry if it happens to you. Following treatment, any redness of the skin will eventually fade.

You may attend the Radiotherapy Nursing Department as part of your skin care during treatment. If your radiotherapy treatment appointment is after 4pm and you have/or need an appointment with the Radiotherapy Nurses, please inform the reception staff, as this service is only available until 5pm.

  • General advice during radiotherapy:

• Wear loose, comfortable clothing around the treatment area; cotton is preferable next to the skin. Sometimes the ink marks can smudge onto your clothing so it is best not to wear anything too special while having your treatment

• Try to avoid treated surfaces rubbing together. A folded cotton handkerchief between two surfaces will help to avoid friction.

  • Advice about washing the treated area:

Please follow the advice below during treatment and until any reaction settles:

• Gently wash the treated skin surface in warm (not hot) water
• If your treated skin is red or broken do not use shower gels, bubble baths, creams, body lotions, moisturisers, deodorants or perfumed soaps
• Showering or immersion in a warm bath is allowed (do not soak in the bath)
• Avoid using a flannel, sponge or shower puff on the treated area
• Pat dry gently with a soft towel.

  • Skincare

• Do not apply any cosmetic products within the treatment area

• Apply the recommended cream to the treatment area once or twice per day initially. Increasing to three or four times daily as treatment proceeds. If you need more cream, or further advice about applying it, please ask your treatment radiographers

• Do not use any preparation or cream on the treated skin except those recommended by the staff

• Avoid hot water bottles, ‘rubs’ or any form of heat on the treated skin

• Avoid ice packs on the treated skin

• Avoid direct sunshine or wind on the treated skin

• Avoid swimming in salt water or chlorinated swimming pools during the course of treatment until any skin reaction has settled.

• If receiving treatment to the head and neck will be advised not to wet shave but can use an electric shaver instead.


Fatigue (extreme tiredness)

You may find you are more tired during your treatment. Listen to your body, continue with normal activities if you feel able but allow yourself some extra time to rest.

Fatigue can last some time after treatment has finished. Combining rest with gentle exercise, such as a short walk, drinking plenty of water and eating a healthy diet can help. Some people are able to continue working but others may find they are too tired.

Remember, please inform the doctor/radiographer treating you or the ward staff about any reactions or side effects you experience.


Most people do not experience nausea  or vomiting during treatment – it depends on the part of the body being treated.

Patients should tell a radiographer if they experience nausea or vomiting. Anti-sickness tablets can be presecribed for nausea. Persistent vomiting can cause dehydration and needs to be treated.

Diarrhoea/ Bowel Looseness

This is a common side effect of treatment for patients receiving treatment to the pelvic area.Patients should tell a radiographer if they experience diarrhoea or bowel looseness.


This is a common side effect of treatment to the pelvic area and can be recognised by the following symptoms:

  • A raised temperature
  •  Increased frequency of passing water
  •  Feeling of pressure in the lower abdomen region
  • Burning or pain on passing of water,
  • Cloudy urine, blood in the urine (haematuria) or strong smelling urine.

If any of these symptoms occur, a radiographer should be told. The most common treatment is a course of antibiotics.

It is important to drink plenty of water during treatment. It keeps the body well hydrated and flushes out toxins.

Hair Loss 

With radiotherapy hair loss only occurs in the area that is being treated. Most hair loss due to radiotherapy is usually temporary and should start to grow back within 2-3 months. Occasionally hair loss can last longer or become permanent, the radiotherapy team will discuss this with you.

If treatment results in hair loss, a referral form will be given to the patient for a consultation with a cosmetician (hairdresser). The cosmetician can supply patients with a wig from a selected range of styles free of charge. Information on this is available from radiographers.

For information about Wig Fitting Services available for cancer patients in the Belfast Health and Social Care Trust contact the Wig Fitting Team at the Macmillan Support and Information Centre by:

Telephone: 028 9063 8979 or 028 9592 2070


Drop In to Our Centre: 77-81 Lisburn Road, Belfast,BT9 7AB.

Discomfort on swallowing, Loss of Appetite and Weight Loss  

If the neck or chest is part of the body being treated, the oesophagus (gullet) may become inflamed causing discomfort on swallowing. 

Sometimes patients can also lose their appetite during their treatment but stress and anxiety may also affect appetite.

Patients should tell a radiographer of any weight loss and loss of appetite as they can make referrals to support services. 

 Read more information on healthy eating and building up your diet