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Side Effects of Radiation Therapy

Medically reviewed by Last updated on Feb 6, 2023.

What do I need to know about side effects of radiation therapy?

The side effects of radiation therapy depend on the area of the body that receives radiation. Early side effects happen shortly after you receive radiation therapy. Late side effects can happen months to years after you receive radiation therapy. Late side effects of radiation therapy may be permanent.

What are common side effects of radiation therapy?

Early and late side effects may include any of the following:

  • Fatigue or loss of energy
  • Pain in the area of the body that is being treated
  • Skin changes such as a sunburn or red skin
  • Hair loss in the area receiving radiation
  • Nausea, vomiting, diarrhea, or indigestion
  • Sores, pain, or dryness in your mouth
  • Difficulty urinating
  • Sexual dysfunction

What causes the side effects of radiation therapy?

Radiation can destroy or harm healthy tissues during treatment. This may cause side effects to happen anywhere in the body where radiation therapy is given. Medicine may be given to protect healthy tissue and prevent side effects of radiation therapy.

How are side effects of radiation therapy diagnosed and treated?

  • Your healthcare provider will ask you about your symptoms and decide if they are side effects of radiation therapy. Radiation therapy may prevent the bone marrow from making red blood cells, white blood cells, and platelets. This may cause low blood counts. Low blood counts are diagnosed with a blood test.
  • Treatment depends on what area of the body is affected. You may be given medicine to treat nausea, vomiting, indigestion, or diarrhea. You may also be given medicine to treat problems in the mouth, or pain in the area that receives radiation. Lotions, ointments, or creams may be given to treat skin problems caused by radiation therapy.

How can I manage my symptoms?

  • Manage your fatigue. Take short naps throughout the day. Do not sleep for more than 1 hour at a time during the day. Ask for help from family or friends with chores and other activities that cause fatigue. Ask your healthcare provider for other ways to manage fatigue.
  • Exercise as directed. Exercise can help decrease fatigue and keep your strength. It can also help prevent severe effects from treatment. Your healthcare provider can help you create an exercise plan that is best for you.
  • Care for your skin as directed.
    • Wear loose-fitting clothing over the area being treated.
    • Use a mild soap and warm water to bathe. Do not use very hot or very cold water on areas of your skin being treated.
    • Do not rub or scratch the area of skin being treated.
    • Wear sunscreen, hats, and clothing to protect your skin when you are outside.
      Prevent Sun Damage
    • Apply lotions, creams, or ointments as directed. Do not put anything on your skin before you ask your healthcare provider.
  • Eat healthy foods as directed. Ask your healthcare provider if you need to be on a special diet. You may be on a special diet if you have nausea, vomiting, or diarrhea. You can do the following to help get enough nutrition and manage the side effects of radiation:
    • Eat 6 to 8 small meals per day.
    • Eat foods high in protein and calories.
    • Do not eat foods that increase side effects. Examples include spicy or acidic foods, and foods with alcohol and caffeine.
    • Eat soft, bland foods, or foods that are easy to eat if you have mouth sores or pain in your esophagus. Examples include milkshakes, protein shakes, pudding, yogurt, soups, and applesauce.
  • Care for your mouth as directed. Keep your mouth clean to prevent infection. Use a soft toothbrush to brush your teeth. Use an oral rinse several times each day as directed. Your healthcare provider may tell you to rinse with a mix of baking soda and salt. Use medicines as directed to decrease pain caused by mouth sores, and relieve dryness. Do not smoke or use products with nicotine.
  • Drink plenty of liquids as directed. Ask how much liquid to drink each day and which liquids are best for you. Liquids may prevent dehydration caused by the side effects of radiation. You may need an oral rehydration solution (ORS). An ORS contains water, salts, and sugar that are needed to replace lost body fluids. Ask what kind of ORS to use, how much to drink, and where to get it.
  • Wear a wig, head scarf, or hat to cover your head. You may have hair loss on your head if your head or neck receives radiation therapy. Hair loss may be difficult to deal with. Talk to your healthcare provider about where you can get a hairpiece or wig.
  • Get support. Radiation therapy can affect your emotional and mental health. Talk to your healthcare provider if you feel angry, scared, helpless, depressed, or frustrated. There are medicines and therapies that can help you manage these side effects. Join a support group or talk to others that have been through radiation therapy.

Where can I find support or more information?

    • American Cancer Society
      250 Williams Street
      Atlanta , GA 30303
      Phone: 1- 800 - 227-2345
      Web Address:
    • National Cancer Institute
      6116 Executive Boulevard, Suite 300
      Bethesda , MD 20892-8322
      Phone: 1- 800 - 422-6237
      Web Address:

When should I seek immediate care?

  • Your heart feels like it is beating faster than usual or you have shortness of breath.
  • You have a headache, dizziness, or blurred vision.
  • You are confused.
  • You see blood in your urine or bowel movements.
  • You vomit blood.
  • You do not urinate for an entire day.
  • You have new or severe pain anywhere in your body.

When should I call my doctor or oncologist?

  • You have a fever.
  • The area of your skin where you received treatment blisters, peels, becomes more painful, or drains fluid.
  • You have trouble swallowing, feel like you are choking, or cough when you are eating or drinking.
  • You lose 5 pounds or more.
  • You feel extremely sad or have thoughts of suicide.
  • Your symptoms do not go away or get worse after you take your medicine.
  • You have questions or concerns about your condition or care.

Care Agreement

You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your healthcare providers to decide what care you want to receive. You always have the right to refuse treatment. The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.