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Single Treatment: Care of Radiation Therapy Side Effects

Information for people having a single treatment of radiation.
Side Effects

Radiation treatment damages cancer cells but can also affect normal tissues in the treatment area. Damage to normal tissues may cause side effects.

These side effects will vary depending on:

  • The amount of radiation prescribed.
  • The area of your body being treated.
  • The size of the treatment area.
  • Whether or not you are having chemotherapy.

Your BC Cancer health care team will explain which side effects you may have during or after your treatment. You will see a nurse or a doctor regularly during your treatment to talk about your radiation side effects. The doctor you see may not be your radiation oncologist.

If you have a problem or concern between visits with the nurse or doctor, please talk to your radiation therapists who can help you right away.

Pain Relief

It is common to have a temporary increase in pain in the treated area. Your BC Cancer health care team may prescribe a pain medication, known as an analgesic, to control your pain. They may tell you to take the analgesic regularly to prevent pain from coming back. Your pain may not go away right after the radiation treatment.

Many people fear getting addicted to strong pain-killers, such as morphine. Addiction does not happen when you take these drugs, as you are told to, for pain.

If your BC Cancer health care team prescribes an opioid pain medication, you will likely have to use a gentle laxative. Constipation (you cannot go poop as often as is normal for you) is a side effect of opioid pain medications. The laxative will help prevent constipation.

Your BC Cancer health care team will give you instructions on how to take the laxative. Go to our page on How to Treat Constipation Caused by your Medications 

When you start taking strong pain medications or start taking a higher dose, you may feel sleepy. This should go away in 2-3 days.

Pain medications can cause nausea (feeling sick to your stomach). Your BC Cancer health care team can prescribe medications to control this. If you are already taking medication, keep taking them unless your BC Cancer health care team tells you to stop.

If your pain is not controlled with your current medication, talk to your family doctor or BC Cancer healthcare team.


Fatigue is a feeling of extreme tiredness. If you are fatigued, you may want to rest and sleep more than is normal for you.

There are many causes of fatigue:

  • Radiation therapy
  • Previous treatments
  • Emotional stress
  • Changes in lifestyle

You may be able to continue your normal lifestyle or you may need to adjust your routine according to your energy level. For more information, go to our Managing Fatigue page.

Skin Care

If you are having external radiation therapy, a skin reaction in the treated area is possible. Talk to your BC Cancer health care team about whether this might happen to you.

The skin in the treated area may become warm, dry or itchy. It may change colour (become pink, red, darker or tanned looking) and you may have hair loss in the treated area.

Most skin reactions begin within the first week or so of starting treatment, but timing can be different for each person.  Some people do not have a skin reaction until after their radiation treatment is finished.

Skin reactions usually go away a few weeks after your last treatment. Some skin changes, like skin darkening or scarring, can be permanent (they will never go away).

Here are some tips to protect your skin and help it feel better:

Lifestyle and well-being

  • Be very gentle with the skin in the treated area.
  • Wear loose, comfortable clothing.
  • Protect the treated skin from wind and direct sunlight. If you cannot cover the area, use sunscreen with an SPF of 30 or higher.
  • It is okay to swim as long as your skin is not broken or irritated. It is best to shower right away after swimming: gently wash off the chlorine, pat dry and apply moisturizer

Hygiene and moisturizing

  • Keep your skin moisturized to prevent dryness. There is no evidence that any cream or product is better for this. If you like a certain product or brand, please continue to use it.
  • If you do not have a moisturizer, use one that is water-based (water or aqua is the first ingredient on the list).
  • Once you start your radiation treatment, use the moisturizer many times each day.
  • You can use deodorants and anti-perspirants.
  • When you bathe or shower, use warm water (not hot) and pat dry with a soft towel.
  • Use an electric razor if you want to shave.
  • If you have a skin reaction, your BC Cancer health care team may ask you to use a steroid-based cream or antibiotic on the treated area.

'Do Nots' for the treatment area

  • Do not use perfume, alcohol, astringents, and adhesives on the treated skin.
  • Avoid extremes of hot or cold (heating pads, ice packs, saunas, etc).
  • Do not use hot tubs or Jacuzzis®.
  • Do not rub, scratch, or massage the treated skin.
Depending on what part of your body is treated, you may have these side effects:

Nausea and Vomiting

If your stomach or intestines is included in the treatment area, you may develop nausea or vomiting. We suggest a non-prescription medication, Dimenhydrinate (Gravol ®). If nausea and vomiting is more frequent or severe, talk to your BC Cancer health care team about a stronger medication.

Weight loss and dehydration (loss of water from the body) can happen with vomiting. It is important to try to drink 6-8 cups (1.5 – 2 litres) of fluids each day and maintain a healthy diet.

Here are some food and drink suggestions when you have nausea and vomiting:

  • Write down all of the things that give you nausea or make you vomit.
  • Eat and drink what works for you. Try foods that have made you feel better in the past.
  • These might be bland foods, sour candy, dry crackers, toast, flat ginger ale, or flat soda.
  • Try not to eat your favorite foods when you have nausea or vomiting. This may cause you to dislike them when you are feeling well.
  • Try eating small meals more often instead of three large meals a day.
  • Sip fluids often during the day including water, juice, soups, broths, sports drinks, herbal tea, or nutritional drinks such as Ensure®.
  • Try chewing food slowly and well.
  • Eat foods that are lukewarm or cold. The smell of hot foods may make your nausea worse.
  • Do not eat fatty, fried, very spicy, or very sweet foods.

If you are not sure what fluids to drink or foods to eat, talk to your BC Cancer health care team.

You can also speak with a BC Cancer dietitian or call 8-1-1 and ask to speak with an oncology dietitian. For more information, go to our Nausea & Vomiting page.

Bowel Reaction 

If your bowel is included in the treatment area, you may experience:

  • Cramping
  • Bloating
  • Frequent, loose bowel movements or diarrhea
  • Passing of watery mucus or even some blood with your stool (poop)

Here are some things you can do that may help with your bowel reactions:

  • Try to drink at least 8 - 10 cups (2 - 2.5 litres) of fluid each day (unless you are on a fluid- restricted diet)
  • Do not take laxatives (medications that help you poop) unless your BC Cancer health care team tells you to
  • Try to maintain a healthy diet
  • Try not to eat foods and drinks that will bother your bowel, such as:
    • Fibrous fruits and vegetables
    • Fried foods
    • Spices and pepper
    • Coffee and tea
    • Cocoa
    • Alcohol

If you are unsure about what to eat or you are having bowel issues, please ask to speak with a BC Cancer dietitian.

You can also go to:

You may also find sitz baths soothing. A sitz bath cleanses and soothes irritated sore skin. Read the Sitz Baths handout or ask your BC Cancer health care team for a copy.

Support Services

BC Cancer helps those living with or affected by cancer to cope with the physical, practical, emotional, and psychological aspects of their care.

If you have any questions or concerns, please talk to your BC Cancer health care team.

Alcohol and Smoking

Alcohol and Smoking

Please try not to smoke during your treatment. Smoking may cause more irritation and increase the side effects you experience.

Stopping smoking has major and immediate benefits for people of all ages. It:

  • Helps improve your body's ability to heal.
  • Improves your body's response to cancer treatment.
  • Lowers the risk of your cancer returning or another cancer developing.
  • Lowers your risk of pneumonia and respiratory failure (when your lungs cannot work properly).

If you use tobacco or have recently quit, ask your BC Cancer health care team for more information. You can also go to our Smoking Cessation Program page.

Depending on the area of your body being treated, alcohol may worsen your side effects. Small amounts of alcohol may be fine for some people. Please check with your BC Cancer health care team.

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