Managing Radiation Therapy Side Effects


Fatigue is a common side effect of cancer. Fatigue can be caused by the cancer itself, radiation therapy or chemotherapy, not eating, low blood counts, poor sleep or depression. While fatigue is not a nutrition problem, it can affect the way that you eat. You may become too tired to eat or prepare foods. It is important to let your doctor know if you are experiencing fatigue.

The following tips may help:

  • Make sure you are getting enough rest. Take several naps or rests during the day and take short walks or do some light exercise if possible
  • Ask your friends and family for help shopping for and preparing foods
  • Keep easy to prepare meals and snacks handy
  • Try to eat smaller meals more often throughout the day
  • Choose foods that are high in protein and calories to get the most nutrition in every bite. Be creative — add calories and protein to foods you eat
  • Make sure to drink enough fluids — dehydration can make you feel tired
  • Talk to your doctor or nurse about your fatigue
  • If you have anemia, make sure to take the medications and/or supplements recommended by your health care team


Problems with constipation (defined as less than 3 bowel movements per week) are common. Stress, lack of exercise, certain medications (especially pain medication), and inadequate fluid or fiber intake may all be contributing factors to constipation.

The following tips may help:

  • Drink plenty of fluids, especially water. Try prune juice or a hot beverage to help promote movement.  Drink with meals and between meals to keep your intake as high as possible
  • Slowly increase fiber in your diet
  • Introduce yogurt with active cultures to relieve adverse intestinal effects associated with increased fiber intake
  • If gas is a problem, limit foods and drinks that cause gas
  • Take walks and exercise regularly, but check with your physician before making any drastic changes in your exercise routine. Try to get as much light exercise as your condition will allow
  • Talk to your doctor about laxatives or stool softeners

Decreased appetite and taste changes

Decreased appetite is one of the most common radiation therapy side effects. Decreased appetite can also be caused by the cancer itself or other side effects of treatment such as nausea and vomiting. Changes in taste can also occur with cancer treatment and this can lead to a decreased desire to eat. Foods can start to have a bitter, metallic or even salty taste. It is important to continue to eat even when you do not feel like doing so. Think of food as one of the medications you must take every day.

Try these tips to help manage your symptoms:

  • Eat smaller meals more often throughout the day instead of 3 large meals
  • Ask your dietitian or doctor about liquid nutritional supplements or "instant breakfast" drinks
  • Keep nutritious snacks available so you can eat whenever you get the urge (nuts, muffins, peanut butter, yogurt, pudding, hardboiled eggs, milk, etc)
  • Liquids can also provide calories and important nutrients when you do not feel like solid food. Try juices, soups or milkshakes
  • Add calories and protein to foods you can tolerate
  • Ask your doctor about medications that can help increase your appetite

To combat taste changes:

  • Try using different marinades with your meat – honey, sweet and sour sauce, fruit juice, Italian dressing, sweet wine
  • Season your food with lemons, vinegar, or pickled foods
  • Be sure to practice proper mouth care
  • Try frozen fruit such as berries, orange slices, grapes or watermelon
  • Use a saline solution to cleanse your taste buds: Mix 1 teaspoon salt + 1 teaspoon baking soda into 1 quart of water
  • If foods taste bitter or metallic: Use plastic silverware, flavor foods with herbs (such as oregano, basil, onion or garlic), or use sauces like ketchup, mustard and barbeque sauce to enhance flavor


Diarrhea has many causes including chemotherapy, radiation therapy, infections, and food sensitivities. It can be an uncomfortable radiation therapy side effect when it is applied to the abdomen.

The following guidelines may help you control these symptoms and keep you as comfortable as possible. Be sure to tell your doctor or nurse if you are experiencing loose or watery stools.

  • Drink fluids to replace what is lost through diarrhea. Drink even if you are not thirsty. Try water, apple juice, apricot and peach nectar, broth, consommé, Jell-O, Gatorade or Powerade, sherbet, skim or low fat milk and low fat yogurt. (Avoid whole milk products.)
  • Eat small amounts of food and drink small amounts of liquid throughout the day rather than three large meals.
  • Follow a low fiber diet. Choose foods low in fiber until your symptoms resolve. Then slowly begin adding fiber into your diet. Use soluble fiber foods or those rich in pectin such as oatmeal, apples, applesauce, bananas and pears.
  • Drink and eat foods high in sodium and potassium. Sodium and potassium are important minerals that are lost when you have diarrhea. Some foods high in potassium include: bananas, baked potatoes, avocado, apricot, cantaloupe, watermelon, peach nectar, meats and halibut. Foods high in sodium are broth, soups, sports drinks, crackers and pretzels. If you have kidney disease, be sure to consult with your doctor before increasing the sodium and potassium in your diet.
  • Try Rice Congee: Take 1 cup of long-cooking rice and combine with 6 to 7 cups of water and 1 tablespoon salt. Cook this according to package directions, typically about 40 minutes. This will be a sticky, soupy mixture.
  • Cleanse the rectum carefully after each bowel movement. Diarrhea can cause irritation and soreness of the rectal area. Using Tucks or baby wipes will help.
  • Water-soluble fiber supplements (Metamucil or Citrucel) often help produce a firmer stool.
  • Avoid a high fiber diet. Foods that are high in fiber include raw fruits and vegetables, whole grain breads and cereals and beans.
  • Avoid foods high in fat as they may also contribute to diarrhea or loose stools.
  • Do not use spices with foods (like pepper, oregano, curry and chili).
  • Avoid alcoholic beverages
  • Avoid milk and milk products if they are irritating to you. They can lead to diarrhea, gas or cramps due to temporary lactose intolerance. Try lactose-free dairy products instead.
  • Avoid foods that may cause gas, such as beans, cabbage, broccoli, corn, cauliflower and spicy foods, if you are experiencing stomach cramps. You may take anti-gas medications — ask your healthcare provider.

Dry mouth / thick saliva

Radiation therapy and some types of chemotherapy can affect the salivary gland and cause dry mouth and a decrease of saliva. The existing saliva may become very thick, sticky and stringy. Saliva is important not only for moisturizing the mouth, but for keeping your teeth and gums healthy. 

This is usually a temporary problem, although in some cases it is permanent. There is no single way to treat dry mouth. However, there are guidelines you can follow:

  • Choose smooth, soft, creamy foods like macaroni and cheese, mashed potatoes, puddings and custards 
  • Take frequent sips of water and drinks without sugar
  • Pause often while speaking to sip liquid
  • Rinse your mouth with a baking soda and salt (saline) solution before and after meals
  • Use nectars, low acid fruit juices, or fresh or canned fruit
  • Suck on fruit juice popsicles, ice chips or other cold foods
  • Try dipping or soaking food in whatever liquid you are drinking
  • Use viscous Lidocaine or other analgesic before meals

What to avoid:

  • Alcohol and tobacco
  • Commercial mouthwashes that contain alcohol
  • Hard, crunchy foods
  • Highly sugared drinks
  • Salty, spicy or acidic foods that irritate your mouth

Nausea / vomiting

Nausea and vomiting are common radiation therapy side effects. Chemotherapy, the cancer itself, certain medications, and anxiety and concerns about your treatment can also cause these side effects. Try to eat when you feel the best. Do not force yourself to eat when nauseous. Try to eat 6 to 8 small meals throughout the day instead of three large meals.

Try the following foods that are easy to digest

  • Gelatin
  • Pudding
  • Toast or crackers
  • English muffins or bagels
  • Carbonated drinks
  • Angel food cake
  • Rice
  • Vanilla wafers
  • Noodles
  • Potatoes
  • Eggs
  • Chicken
  • Lunch meat
  • Canned or fresh fruit
  • Clear liquids, such as broth, tea, fruit punch, gelatin, Popsicles, sports drinks, clear sodas, water or ice chips
  • Canned or fresh fruit

Other tips:

  • Eat and drink slowly. Try drinks and foods at room temperature or cooler as hot foods may add to your nausea.
  • Sip most of your fluids between meals. Try using a straw or covered mug.
  • Rest after eating, but don’t lie down until an hour after your meal
  • Avoid wearing tight-fitting clothes
  • Contact your doctor if unable to keep down liquids

Sore mouth and throat

If your mouth and throat become sore during cancer treatment, healing will occur more rapidly if you drink plenty of fluids and continue to eat well. Choose foods high in protein such as dried beans, poultry, eggs, peanut butter, milk, cheese and yogurt.

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