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Nausea and Vomiting


What they are

Radiation therapy can cause nausea, vomiting, or both. Nausea is when you feel sick to your stomach and feel like you are going to throw up. Vomiting is when you throw up food and fluids. You may also have dry heaves, which happen when your body tries to vomit even though your stomach is empty.


Why they occur

Nausea and vomiting can occur after radiation therapy to the stomach, small intestine, colon, or parts of the brain. Your risk for nausea and vomiting depends on how much radiation you are getting, how much of your body is in the treatment area, and whether you are also having chemotherapy.


How long they last

Nausea and vomiting may occur 30 minutes to many hours after your radiation therapy session ends. You are likely to feel better on days that you do not have radiation therapy.



Radiation to the shaded area may cause diarrhea.


Ways to manage

  • Prevent nausea. The best way to keep from vomiting is to prevent nausea. One way to do this is by having bland, easy-to-digest foods and drinks that do not upset your stomach. These include toast, gelatin, and apple juice. To learn more, see the list of Foods and Drinks That Are Easy on the Stomach.

  • Try to relax before treatment. You may feel less nausea if you relax before each radiation therapy treatment. You can do this by spending time doing activities you enjoy, such as reading a book, listening to music, or other hobbies.

  • Plan when to eat and drink. Some people feel better when they eat before radiation therapy; others do not. Learn the best time for you to eat and drink. For example, you might want a snack of crackers and apple juice 1 to 2 hours before radiation therapy. Or, you might feel better if you have treatment on an empty stomach, which means not eating 2 to 3 hours before treatment.

  • Eat small meals and snacks. Instead of eating 3 large meals each day, you may want to eat 5 or 6 small meals and snacks. Make sure to eat slowly and do not rush.

  • Have foods and drinks that are warm or cool (not hot or cold). Before eating or drinking, let hot food and drinks cool down and cold food and drinks warm up.

  • Talk with your doctor or nurse. He or she may suggest a special diet of foods to eat or prescribe medicine to help prevent nausea, which you can take 1 hour before each radiation therapy session. You might also ask your doctor or nurse about acupuncture, which may help relieve nausea and vomiting caused by cancer treatment.


Eat five or six small meals and snacks each day instead of three large meals.


Learn more from Eating Hints, a book from the National Cancer Institute. To get a free copy, contact the Cancer Information Service at 1-800-4-CANCER.